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Canadian Journal of Cardiology

2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Position Statement on the Management of Ventricular Tachycardia and Fibrillation in Patients With Structural Heart Disease

      Abstract

      This Canadian Cardiovascular Society position statement is focused on the management of sustained ventricular tachycardia (VT) and ventricular fibrillation (VF) that occurs in patients with structural heart disease (SHD), including previous myocardial infarction, dilated cardiomyopathy, and other forms of nonischemic cardiomyopathy. This patient population is rapidly increasing because of advances in care and improved overall survival of patients with all forms of SHD. In this position statement, the acute and long-term management of VT/VF are outlined, and the many unique aspects of care in this population are emphasized. The initial evaluation, acute therapy, indications for chronic suppressive therapy, choices of chronic suppressive therapy, implantable cardioverter-defibrillator programming, alternative therapies, and psychosocial care are reviewed and recommendations for optimal care are provided. The target audience for this statement includes all health professionals involved in the continuum of care of patients with SHD and VT/VF.

      Résumé

      Le présent énoncé de position de la Société canadienne de cardiologie est axé sur la prise en charge de la tachycardie ventriculaire (TV) et de la fibrillation ventriculaire (FV) soutenues qui surviennent chez les patients présentant une cardiopathie structurelle, par exemple des antécédents d’infarctus du myocarde, une cardiomyopathie dilatée et d’autres formes de cardiomyopathie non ischémique. Cette population de patients augmente rapidement, en raison des avancées réalisées en matière de soins et de l’amélioration de la survie globale des patients présentant une cardiopathie structurelle sous une forme ou une autre. L’énoncé de position présente les grandes lignes de la prise en charge aiguë et à long terme de la TV et de la FV, et fait ressortir les nombreux aspects propres aux soins dont cette population a besoin. L’évaluation initiale, le traitement aigu, les indications commandant un traitement suppresseur prolongé, les options de traitement suppresseur prolongé, la programmation des défibrillateurs cardioverteurs implantables, les thérapies parallèles et les soins psychosociaux sont examinés, et des recommandations concernant les soins optimaux sont formulées. Ce document est destiné à tous les professionnels de la santé qui interviennent dans le continuum des soins aux patients présentant une cardiopathie structurelle et une TV/FV.

      1. Scope of the Position Statement

      This Canadian Cardiovascular Society position statement is focused on the acute and long-term management of sustained ventricular tachycardia (VT) and ventricular fibrillation (VF) in patients with structural heart disease (SHD), defined by the presence of abnormal myocardium and scar. SHD includes conditions such as myocardial infarction (MI), dilated cardiomyopathies, hypertrophic cardiomyopathy, infiltrative cardiomyopathies (eg, sarcoidosis), and arrhythmogenic right ventricular cardiomyopathy (ARVC). Almost all such patients have an indication for an implantable cardioverter-defibrillator (ICD).
      • Bennett M.
      • Parkash R.
      • Nery P.
      • et al.
      Canadian Cardiovascular Society/Canadian Heart Rhythm Society 2016 implantable cardioverter-defibrillator guidelines.
      Although many of the recommendations in this document can apply to patients with complex congenital heart disease, this population is not specifically addressed. The reader is referred to other published resources on the management of VT/VF in that population.
      • Khairy P.
      Arrhythmias in adults with congenital heart disease: what the practicing cardiologist needs to know.
      ,
      • Khairy P.
      • Van Hare G.F.
      • Balaji S.
      • et al.
      PACES/HRS expert consensus statement on the recognition and management of arrhythmias in adult congenital heart disease: developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American College of Cardiology (ACC), the American Heart Association (AHA), the European Heart Rhythm Association (EHRA), the Canadian Heart Rhythm Society (CHRS), and the International Society for Adult Congenital Heart Disease (ISACHD).
      This statement is not intended to replace the guidelines for cardiopulmonary resuscitation,
      • Neumar R.W.
      • Shuster M.
      • Callaway C.W.
      • et al.
      Part 1: executive summary: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care.
      but provides guidance for the ongoing care of patients with VT/VF after resuscitation. This statement is targeted at health professionals involved in the continuum of care of patients with SHD and VT/VF, including emergency medicine, critical care, internal medicine, and cardiology. The management of premature ventricular complexes and nonsustained VT in patients with SHD, and the management of VT/VF in patients with structurally normal hearts (including inherited arrhythmia syndromes) are beyond the scope of this statement.

      2. Position Statement Development

      This position statement was written by a multidisciplinary panel of experts who care for patients with VT/VF (see Supplemental Table S1). The recommendations were developed using the Grading of Recommendations, Assessment, Development, and Evaluation standards with strength of recommendations classified as “strong” or “conditional.” The recommendations are presented, along with their background and rationale.

      3. Definitions

      Sustained VT is defined as an episode of VT lasting > 30 seconds or requiring intervention before 30 seconds.
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards (ACC/AHA/HRS Writing Committee to Develop Data Standards on Electrophysiology).
      Hemodynamically stable VT is defined as VT without signs or symptoms of organ hypoperfusion. Electrical storm (also known as VT/VF storm) is defined as the occurrence of 3 or more distinct episodes of VT/VF within 24 hours. Monomorphic VT has similar QRS complexes on the electrocardiogram (ECG), whereas polymorphic VT has changing beat-to-beat morphology. Torsade de pointes is polymorphic VT occurring in the setting of QT prolongation. VF is chaotic and does not have distinct QRS complexes on the ECG. Monomorphic VT might degenerate to polymorphic VT or VF. A summary of classification and mechanisms of VT and VF in patients with SHD is presented in Supplemental Table S2.

      4. Incidence and Prognosis of Sustained VT/VF in Patients With SHD

      Ventricular arrhythmias can cause sudden cardiac death (SCD) or arrest, most frequently in those with previous MI.
      • Kuck K.H.
      • Cappato R.
      • Siebels J.
      • Ruppel R.
      Randomized comparison of antiarrhythmic drug therapy with implantable defibrillators in patients resuscitated from cardiac arrest : the Cardiac Arrest Study Hamburg (CASH).
      The past decade saw a decreasing incidence of post-MI VT/VF causing SCD, yet no change in the incidence of SCD in patients without ischemic heart disease.
      • Bunch T.J.
      • White R.D.
      Trends in treated ventricular fibrillation in out-of-hospital cardiac arrest: ischemic compared to non-ischemic heart disease.
      The development of VT/VF in patients with SHD is associated with a higher risk of future episodes of VT/VF, of electrical storm, and of death.
      • Sweeney M.O.
      • Sherfesee L.
      • DeGroot P.J.
      • Wathen M.S.
      • Wilkoff B.L.
      Differences in effects of electrical therapy type for ventricular arrhythmias on mortality in implantable cardioverter-defibrillator patients.

      5. Initial Evaluation and Management of SHD Patients With Sustained VT/VF

      Patients who present with VT/VF often have a preexisting diagnosis of SHD. However, VT/VF might be the initial indication of the presence of SHD for some patients. The initial evaluation must rapidly assess the need for acute intervention and identify potential etiologies or precipitating factors. When the patient is stabilized, the evaluation should include a complete history and examination, comprehensive laboratory testing, and assessment of cardiac function (Fig. 1).
      • 1.
        We recommend that all patients presenting with VT/VF undergo a comprehensive initial evaluation including a detailed history, physical examination, laboratory investigations, ECG, ICD interrogation (if present) and transthoracic echocardiography (Strong Recommendation, Low-Quality Evidence).
      Values and preferences. A comprehensive initial evaluation can be performed quickly and at a reasonable cost. This evaluation is critical for guiding subsequent treatment.
      Practical tip. If not previously diagnosed, most forms of SHD will be apparent after this initial evaluation. Unless a reversible cause is identified (such as acute MI), all patients with VT/VF and SHD should be referred for consideration of an ICD, if not already present, for the prevention of sudden death.
      Figure thumbnail gr1
      Figure 1Initial evaluation of patients with sustained VT/VF. ∗ Even if recently performed, a repeat transthoracic echocardiogram should be acquired to rule out acute changes. BNP, brain natriuretic peptide; CAD, coronary artery disease; CBC, complete blood count; NT, N-terminal; STEMI, ST-elevation myocardial infarction; TSH, thyroid stimulating hormone; VF, ventricular fibrillation; VT, ventricular tachycardia.
      A 12-lead ECG recorded during VT is important to localize VT and give insight into pathophysiology. An ECG performed after restoration of the underlying rhythm can be used to evaluate for reversible causes, such as ischemia and QT prolongation. Laboratory tests might identify precipitating factors, prognostic factors, and contraindications to specific antiarrhythmic drug (AAD) therapies (such as renal or hepatic dysfunction). Cardiac imaging is useful to determine the presence of underlying SHD and aid prognostication. Transthoracic echocardiography remains the first-line diagnostic imaging tool for assessment of ventricular function, wall motion abnormalities, and valvular disease. Nevertheless, it has limitations in identifying scar. Cardiac magnetic resonance (CMR) imaging, with gadolinium contrast, can support the diagnosis, particularly with nonischemic and infiltrative cardiomyopathies.
      • Neilan T.G.
      • Farhad H.
      • Mayrhofer T.
      • et al.
      Late gadolinium enhancement among survivors of sudden cardiac arrest.
      ,
      • White J.A.
      • Fine N.M.
      • Gula L.
      • et al.
      Utility of cardiovascular magnetic resonance in identifying substrate for malignant ventricular arrhythmias.
      • 2.
        We recommend that CMR imaging be performed in patients who present with VT/VF when the initial evaluation has failed to establish the etiology of the underlying heart disease (Strong Recommendation, Moderate-Quality Evidence).
      Values and preferences. CMR imaging provides enhanced assessment of the presence, location, and quantity of myocardial scar in patients with SHD and can identify inflammatory conditions, such as myocarditis.
      Practical tip. In patients for whom the initial workup is not definitive, early use of CMR imaging has a high diagnostic and prognostic yield.
      Emergent angiography should be performed for VT/VF in the setting of ST-elevation MI. Urgent angiography should also be considered in those who present with polymorphic VT/VF potentially due to acute ischemia. Other coronary imaging modalities can be considered if there is a lower index of suspicion of coronary disease. Monomorphic VT is rarely caused by acute ischemia, but coronary imaging might be warranted to establish the presence and severity of coronary artery disease.
      Positron emission tomography can be useful in identifying patients with active inflammatory states, such as sarcoidosis, when other imaging modalities yield negative or equivocal findings.
      • Chareonthaitawee P.
      • Beanlands R.S.
      • Chen W.
      • et al.
      Joint SNMMI–ASNC expert consensus document on the role of 18F-FDG PET/CT in cardiac sarcoid detection and therapy monitoring.
      Invasive electrophysiological testing of patients with wide complex tachycardia might be useful to distinguish VT from SVT or to diagnose bundle-branch reentry VT.
      • Balasundaram R.
      • Rao H.B.
      • Kalavakolanu S.
      • Narasimhan C.
      Catheter ablation of bundle branch reentrant ventricular tachycardia.

      5.1 Management of hemodynamically unstable VT/VF

      Figure 2 illustrates the acute management of patients with VT/VF. In patients with unstable VT electrical cardioversion/defibrillation is indicated and advanced cardiac life support algorithms should be followed (Fig. 2A).
      • Panchal A.R.
      • Berg K.M.
      • Kudenchuk P.J.
      • et al.
      2018 American Heart Association focused update on advanced cardiovascular life support use of antiarrhythmic drugs during and immediately after cardiac arrest: an update to the American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care.
      ,
      • Link M.S.
      • Berkow L.C.
      • Kudenchuk P.J.
      • et al.
      Part 7: adult advanced cardiovascular life support: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care.
      In patients with shock-refractory VF or VT, bolus intravenous (I.V.) amiodarone or lidocaine should be used.
      • Kudenchuk P.J.
      • Brown S.P.
      • Daya M.
      • et al.
      Amiodarone, lidocaine, or placebo in out-of-hospital cardiac arrest.
      ,
      • Dorian P.
      • Cass D.
      • Schwartz B.
      • et al.
      Amiodarone as compared with lidocaine for shock-resistant ventricular fibrillation.
      Intravenous AAD dosing is summarized in Supplemental Table S3.
      • 3.
        We recommend the administration of I.V. amiodarone or lidocaine for acute treatment of patients with shock-refractory VT/VF (failure of at least 1 attempt at defibrillation) or patients with recurrent polymorphic VT/VF, unless there is a strong suspicion of torsade de pointes (Strong Recommendation, Moderate-Quality Evidence).
      Values and preferences. The outcome of unstable patients with VT/VF arrest is poor, particularly in out-of-hospital settings. There is likely a small benefit to these drugs, which outweigh their risks.
      Practical tip. Simplified, rather than weight-based dosing is easier in the setting of unstable VT/VF. Amiodarone can be given as 300 mg I.V. push (150 mg I.V. push for those < 45 kg) with a subsequent dose of 150 mg I.V. push in the event of failure of another shock. Lidocaine can be given as 100 mg I.V. push (50 mg I.V. push if < 45 kg) with a subsequent dose of 50 mg I.V. push in the event of failure of another shock.
      Figure thumbnail gr2a
      Figure 2Initial management of sustained VT/VF. The initial management of VF and polymorphic VT is outlined in (A), whereas the initial management of monomorphic VT is outlined in (B). For unstable patients with VT/VF that recurs despite defibrillation/cardioversion or VT/VF that persists despite 1-2 attempts at defibrillation/cardioversion, intravenous (I.V.) amiodarone or lidocaine should be administered. For unstable VT/VF that recurs, the treatment should follow the electrical storm recommendations. See the accompanying text for drug dosing. ACLS, Advanced Cardiac Life Support; ACS, acute coronary syndrome; VF, ventricular fibrillation; VT, ventricular tachycardia.
      Figure thumbnail gr2b
      Figure 2Initial management of sustained VT/VF. The initial management of VF and polymorphic VT is outlined in (A), whereas the initial management of monomorphic VT is outlined in (B). For unstable patients with VT/VF that recurs despite defibrillation/cardioversion or VT/VF that persists despite 1-2 attempts at defibrillation/cardioversion, intravenous (I.V.) amiodarone or lidocaine should be administered. For unstable VT/VF that recurs, the treatment should follow the electrical storm recommendations. See the accompanying text for drug dosing. ACLS, Advanced Cardiac Life Support; ACS, acute coronary syndrome; VF, ventricular fibrillation; VT, ventricular tachycardia.

      5.2 Electrical storm

      Initial management of electrical storm often includes a combination of sedation, β-blockade, and AAD therapy. Short-acting β-blockers, (eg, esmolol) might be considered to assess tolerability. In a recent randomized trial, non-selective β-blockade with propranolol, given immediately and continued during the hospitalization, was superior to selective β1 blockade (metoprolol) for suppressing VT, in conjunction with usual care including I.V. amiodarone.
      • Chatzidou S.
      • Kontogiannis C.
      • Tsilimigras D.I.
      • et al.
      Propranolol versus metoprolol for treatment of electrical storm in patients with implantable cardioverter-defibrillator.
      If initial management strategies fail, general anaesthesia can be considered. Dexmedetomidine and propofol are preferred sedating agents because of their sedative and sympatholytic effects.
      • Mulpuru S.K.
      • Patel D.V.
      • Wilbur S.L.
      • Vasavada B.C.
      • Furqan T.
      Electrical storm and termination with propofol therapy: a case report.
      ,
      • Parent B.A.
      • Munoz R.
      • Shiderly D.
      • Chrysostomou C.
      Use of dexmedetomidine in sustained ventricular tachycardia.
      Patients with an ICD and electrical storm should undergo early device interrogation; ICD programming can be adjusted (such as optimizing antitachycardia pacing [ATP]) or ICD therapy can be temporarily disabled, if appropriate.
      Amiodarone is useful for electrical storm in patients with SHD, and a target loading dose of 1000-2000 mg I.V. over the first 24 hours is recommended (Supplemental Table S3).
      • Kowey P.R.
      • Levine J.H.
      • Herre J.M.
      • et al.
      Randomized, double-blind comparison of intravenous amiodarone and bretylium in the treatment of patients with recurrent, hemodynamically destabilizing ventricular tachycardia or fibrillation. The Intravenous Amiodarone Multicenter Investigators Group.
      ,
      • Levine J.H.
      • Massumi A.
      • Scheinman M.M.
      • et al.
      Intravenous amiodarone for recurrent sustained hypotensive ventricular tachyarrhythmias. Intravenous Amiodarone Multicenter Trial Group.
      Combinations of AADs with distinct mechanisms of action (eg, amiodarone and lidocaine) might prove effective for acute arrhythmia suppression in selected patients. Ablation should be considered in selected patients with drug-refractory electrical storm due to monomorphic VT.
      • Komatsu Y.
      • Hocini M.
      • Nogami A.
      • et al.
      Catheter ablation of refractory ventricular fibrillation storm after myocardial infarction.
      ,
      • Vergara P.
      • Tung R.
      • Vaseghi M.
      • et al.
      Successful ventricular tachycardia ablation in patients with electrical storm reduces recurrences and improves survival.
      For recurrent polymorphic VT or VF in the absence of acute ischemia, administration of I.V. magnesium can be considered. Treatment directed at acute heart failure should also be considered, because this can precipitate VT/VF.
      Refractory patients might benefit from thoracic epidural anaesthesia or percutaneous cardiac sympathetic denervation. For recurrent VT/VF with prolonged hemodynamic instability, mechanical circulatory support might be considered (the readers are referred to the reference list of a review for temporary mechanical support in critical cardiac care
      • Nagpal A.D.
      • Singal R.K.
      • Arora R.C.
      • Lamarche Y.
      Temporary mechanical circulatory support in cardiac critical care: a state of the art review and algorithm for device selection.
      ).
      • 4.
        We recommend the use of β-blockade, preferably nonselective β-blockade, and I.V. amiodarone in patients with electrical storm in the setting of underlying SHD (Strong Recommendation, Moderate-Quality Evidence).
      Values and preferences. The outcomes of patients with electrical storm are poor. As such, aggressive intervention is often required.
      Practical tip. In patients with stable blood pressure, oral, short-acting, nonselective β-blockers should be used preferentially (such as propranolol 40 mg orally every 6 hours).

      5.3 Stable monomorphic VT

      Electrical cardioversion or I.V. AADs can acutely treat stable monomorphic VT in patients with SHD (Fig. 2B). Procainamide is superior to amiodarone for conversion of hemodynamically tolerated monomorphic VT, with higher efficacy and fewer adverse effects.
      • Ortiz M.
      • Martin A.
      • Arribas F.
      • et al.
      Randomized comparison of intravenous procainamide vs. intravenous amiodarone for the acute treatment of tolerated wide QRS tachycardia: the PROCAMIO study.
      Procainamide is also superior to lidocaine for acute termination of stable monomorphic VT.
      • deSouza I.S.
      • Martindale J.L.
      • Sinert R.
      Antidysrhythmic drug therapy for the termination of stable, monomorphic ventricular tachycardia: a systematic review.
      • 5.
        We recommend electrical cardioversion or I.V. procainamide for the acute treatment of stable monomorphic VT in patients with SHD (Strong Recommendation, Moderate-Quality Evidence).
      Values and preferences. Procainamide therapy can frequently terminate monomorphic VT without the need for cardioversion, but might interact with chronic AADs (such as amiodarone or sotalol). Cardioversion, although effective at terminating monomorphic VT, requires sedation and does not prevent recurrent VT. Selection of the preferred first-line approach should take into consideration local resources and expertise, as well as patient preference.
      Practical tip. There are a wide variety of reported doses of I.V. procainamide used in the literature but a rapid infusion of 10 mg/kg over 20 minutes has good efficacy and a low rate of hypotension (Supplemental Table S3). The infusion can be slowed if hypotension is encountered. This can be followed by an ongoing infusion of 1-2 mg/min. Amiodarone I.V. (150 mg I.V. over 10 minutes, followed by an infusion of 1 mg/min for 6 hours, followed by 0.5 mg/min for 18 hours) or lidocaine (1 mg/kg I.V. push, followed by 1-2 mg/min infusion), can be given as second-line alternatives to procainamide.

      5.4 Polymorphic VT

      Most patients with sustained polymorphic VT are unstable and should be acutely treated as per VF (Fig. 2) with aggressive early investigation and treatment of underlying causes, such as acute ischemia (most commonly), decompensated heart failure or other potential contributors (Supplemental Table S2). Polymorphic VT due to QT prolongation (torsade de pointes) can be related to drugs, electrolyte disturbance (hypokalemia/hypomagnesemia), or (rarely) concomitant long QT syndrome. Magnesium can be useful in patients with torsade de pointes regardless of measured serum magnesium levels,
      • Topol E.J.
      • Lerman B.B.
      Hypomagnesemic torsades de pointes.
      but not for ischemia-related ventricular arrhythmias.
      • Roffe C.
      • Fletcher S.
      • Woods K.L.
      Investigation of the effects of intravenous magnesium sulphate on cardiac rhythm in acute myocardial infarction.
      Although no evidence-based dosing or targets exist for VT, it would be reasonable to target a serum potassium ≥ 4.0 mmol/L and serum magnesium ≥ 0.9-1.0 mmol/L.

      6. Initiation of Long-Term Suppressive Therapy for Sustained VT/VF

      6.1 Goals for initiating long-term suppressive therapy for VT/VF

      Although appropriate ICD shocks are often acutely life-saving, they are associated with a subsequent increased mortality risk, even compared with VT/VF terminated with ATP therapy. Furthermore, ICD shocks can result in significant psychosocial morbidity (see section 11. Psychosocial Care of Patients With VT/VF). Treating VT/VF should aim to reduce VT/VF burden and ICD shocks. Optimization of ICD programming (see section 9. ICD Programming in Patients With Sustained VT/VF in the Setting of SHD) should be performed in all patients with VT/VF to minimize shocks. Suppression of VT/VF might be accomplished by use of AADs and/or catheter ablation, the latter predominantly indicated for monomorphic VT (Fig. 3).
      Figure thumbnail gr3
      Figure 3When to initiate chronic suppressive therapy for sustained VT/VF. ∗ Escalation of AAD therapy: increasing the AAD dose, switching to a more potent agent (ie, amiodarone), or using combination therapy. AAD, antiarrhythmic drug; ICD, implantable cardioverter-defibrillator; VF, ventricular fibrillation; VT, ventricular tachycardia.

      6.2 First episode of sustained VT/VF

      The risk of recurrent VT/VF after a first event, without suppressive therapy is approximately 22% after 1 year and approximately 53% after 2 years.
      • Connolly S.J.
      • Dorian P.
      • Roberts R.S.
      • et al.
      Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
      • Pacifico A.
      • Hohnloser S.H.
      • Williams J.H.
      • et al.
      Prevention of implantable-defibrillator shocks by treatment with sotalol. d,l-Sotalol Implantable Cardioverter-Defibrillator Study Group.
      • Kuck K.H.
      • Schaumann A.
      • Eckardt L.
      • et al.
      Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial.
      Catheter ablation after the first episode of monomorphic VT reduces recurrences of VT (hazard ratios 0.54-0.61 vs controls for recurrent VT at 1-2 years),
      • Kuck K.H.
      • Schaumann A.
      • Eckardt L.
      • et al.
      Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial.
      • Dinov B.
      • Arya A.
      • Bertagnolli L.
      • et al.
      Early referral for ablation of scar-related ventricular tachycardia is associated with improved acute and long-term outcomes: results from the Heart Center of Leipzig ventricular tachycardia registry.
      • Willems S.
      • Tilz Roland R.
      • Steven D.
      • et al.
      Preventive or deferred ablation of ventricular tachycardia in patients with ischemic cardiomyopathy and implantable defibrillator (BERLIN VT): a multicenter randomized trial.
      but these studies did not routinely use active controls with AAD therapy (AAD use was only 32%-35%). In the most recent randomized trial, VT ablation did not reduce the composite outcome of death, VT hospitalization, or worsening heart failure, compared with ICD therapy alone.
      • Willems S.
      • Tilz Roland R.
      • Steven D.
      • et al.
      Preventive or deferred ablation of ventricular tachycardia in patients with ischemic cardiomyopathy and implantable defibrillator (BERLIN VT): a multicenter randomized trial.
      No randomized trial has specifically evaluated the effect of AAD therapy after a first VT/VF episode, although these patients were represented in larger trials that assessed drug efficacy. Although usually unnecessary, suppressive therapy beyond β-blockade after a first VT/VF episode might be warranted despite the potential risks of therapy, particularly if the patient experienced significant morbidity with the index episode (Fig. 3). Importantly, ICD implantation should be performed with optimization of programming to minimize future shocks (see section 9. ICD Programming in Patients With Sustained VT/VF in the Setting of SHD).

      6.3 Recurrent sustained VT/VF

      Recurrent episodes of VT/VF despite optimal medical therapy are associated with increased risks of electrical storm and mortality
      • Connolly S.J.
      • Dorian P.
      • Roberts R.S.
      • et al.
      Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
      ,
      • Kuck K.H.
      • Schaumann A.
      • Eckardt L.
      • et al.
      Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial.
      ,
      • Sapp J.L.
      • Wells G.A.
      • Parkash R.
      • et al.
      Ventricular tachycardia ablation versus escalation of antiarrhythmic drugs.
      and therefore treatment with AADs or catheter ablation is generally recommended (see Fig. 3 and sections 7. AAD Therapy for Long-term Management of Sustained VT/VF and 8. Catheter Ablation for the Treatment of Sustained VT in Patients With SHD). In addition to optimizing β-blockade and ICD programming (see section 9. ICD Programming in Patients With Sustained VT/VF in the Setting of SHD), all patients should have other cardiac therapy optimized. β-Blockers should be uptitrated to evidence-based doses for heart failure, when heart rate, blood pressure, and side effects allow.
      • Ezekowitz J.A.
      • O’Meara E.
      • McDonald M.A.
      • et al.
      2017 Comprehensive update of the Canadian Cardiovascular Society Guidelines for the management of heart failure.
      Ideally, β-blocker doses should target a resting heart rate of 50-65 beats per minute.
      • 6.
        In patients with SHD and new or recurrent VT/VF, we recommend: (1) optimizing β-blocker dose in all patients; (2) optimizing ICD programming; and (3) consideration of initiation of additional suppressive therapy (either class III AAD therapy or catheter ablation), particularly in patients with VT/VF resulting in ICD shock(s), in those with a high burden of VT/VF, and in those with severe symptoms/hemodynamic compromise or psychosocial distress (Strong Recommendation, Low-Quality Evidence).
      Values and preferences. The risk of recurrent VT/VF is high, especially after multiple events. The negative effect of recurrent events, particularly those associated with severe symptoms or ICD shocks, warrants therapy.
      Practical tip. For patients receiving no or a low-dose β-blocker, consider the introduction/titration of a β-blocker alone. However, in patients already receiving reasonable doses of β-blocker, additional suppressive therapy should be used.

      6.4 Electrical storm

      Electrical storm has a 2-year recurrence rate of 45%-60%.
      • Izquierdo M.
      • Ruiz-Granell R.
      • Ferrero A.
      • et al.
      Ablation or conservative management of electrical storm due to monomorphic ventricular tachycardia: differences in outcome.
      ,
      • Morawski S.
      • Pruszkowska P.
      • Sredniawa B.
      • Lenarczyk R.
      • Kalarus Z.
      Long-term outcome of catheter ablation and other form of therapy for electrical storm in patients with implantable cardioverter-defibrillators.
      Chronic suppressive AAD therapy is almost always indicated. When AAD therapy is unsuccessful, catheter ablation for monomorphic VT can reduce VT recurrences.
      • Komatsu Y.
      • Hocini M.
      • Nogami A.
      • et al.
      Catheter ablation of refractory ventricular fibrillation storm after myocardial infarction.
      ,
      • Vergara P.
      • Tung R.
      • Vaseghi M.
      • et al.
      Successful ventricular tachycardia ablation in patients with electrical storm reduces recurrences and improves survival.
      • 7.
        We recommend optimizing β-blocker dose and using additional suppressive therapy (amiodarone or catheter ablation), in patients with SHD who present with electrical storm (Strong Recommendation, Moderate-Quality Evidence).
      Values and preferences. The poor prognosis and high recurrence rate of VT/VF in patients with electrical storm warrants long-term suppressive therapy to reduce the risk of recurrence.
      Practical tip. After the acute treatment of electrical storm, in addition to β-blocker therapy, chronic suppressive therapy should be initiated/undertaken while in hospital. Amiodarone is the preferred AAD for patients with electrical storm.

      7. AAD Therapy for Long-Term Management of Sustained VT/VF

      AADs (with the exception of β-blockers) are not known to improve survival in patients with SHD
      • Singh S.N.
      • Fletcher R.D.
      • Fisher S.
      • et al.
      Veterans Affairs congestive heart failure antiarrhythmic trial. CHF STAT Investigators.
      ,
      • Cairns J.A.
      • Connolly S.J.
      • Roberts R.
      • Gent M.
      Randomised trial of outcome after myocardial infarction in patients with frequent or repetitive ventricular premature depolarisations: CAMIAT. Canadian Amiodarone Myocardial Infarction Arrhythmia Trial Investigators.
      and cannot replace ICD therapy, which has consistently resulted in survival benefit compared with AAD therapy for VT/VF. Nevertheless, in patients who are not candidates for ICD implantation, amiodarone might be useful for treatment of VT/VF.
      • Claro J.C.
      • Candia R.
      • Rada G.
      • et al.
      Amiodarone versus other pharmacological interventions for prevention of sudden cardiac death.

      7.1 β-Blockers

      β-Blocker therapy is recommended in patients with SHD for the prevention of VT/VF and sudden death, in conjunction with an ICD.
      • Ellison K.E.
      • Hafley G.E.
      • Hickey K.
      • et al.
      Effect of beta-blocking therapy on outcome in the Multicenter UnSustained Tachycardia Trial (MUSTT).
      ,
      Effect of metoprolol CR/XL in chronic heart failure: Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF).
      Clinical data support a modest AAD effect of β-blockers compared with placebo.
      • Levine J.H.
      • Mellits E.D.
      • Baumgardner R.A.
      • et al.
      Predictors of first discharge and subsequent survival in patients with automatic implantable cardioverter-defibrillators.
      ,
      • Deftereos S.
      • Giannopoulos G.
      • Kossyvakis C.
      • et al.
      Relation of ventricular tachycardia/fibrillation to beta-blocker dose maximization guided by pacing mode analysis in nonpacemaker-dependent patients with implantable cardioverter-defibrillator.
      • 8.
        We recommend β-blocker therapy, titrated to a maximally tolerated dose (optimized dose), in patients with SHD with VT/VF (Strong Recommendation, Moderate-Quality Evidence).
      Values and preferences. β-Blockers are almost always indicated in patients with SHD, particularly those with VT/VF. The risks of β-blocker therapy are outweighed by the many benefits.
      Practical tip. Most patients with SHD will also have nonarrhythmic indications for β-blocker therapy, such as for treatment of coronary artery disease with ischemia or heart failure with reduced ejection fraction.

      7.2 Sotalol

      Sotalol has better efficacy in reducing VT compared with placebo or β-blocker monotherapy but is less effective than amiodarone.
      • Connolly S.J.
      • Dorian P.
      • Roberts R.S.
      • et al.
      Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
      ,
      • Pacifico A.
      • Hohnloser S.H.
      • Williams J.H.
      • et al.
      Prevention of implantable-defibrillator shocks by treatment with sotalol. d,l-Sotalol Implantable Cardioverter-Defibrillator Study Group.
      Practical considerations for the use of sotalol are outlined in Table 1. Sotalol has a side effect profile similar to other β-blockers with the added risk of QT prolongation. However, rates of sotalol discontinuation were higher than other β-blockers in an open-label randomized trial (23.5% vs 5.3% at 1 year).
      • Connolly S.J.
      • Dorian P.
      • Roberts R.S.
      • et al.
      Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
      Sotalol proarrhythmic risk might be higher in patients with advanced heart failure,
      • Waldo A.L.
      • Camm A.J.
      • deRuyter H.
      • et al.
      Effect of d-sotalol on mortality in patients with left ventricular dysfunction after recent and remote myocardial infarction. The SWORD Investigators. Survival with oral d-sotalol.
      but its use might be appropriate in those with less severe heart failure or as an adjunct to an ICD.
      • Connolly S.J.
      • Dorian P.
      • Roberts R.S.
      • et al.
      Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
      ,
      • Pacifico A.
      • Hohnloser S.H.
      • Williams J.H.
      • et al.
      Prevention of implantable-defibrillator shocks by treatment with sotalol. d,l-Sotalol Implantable Cardioverter-Defibrillator Study Group.
      Sotalol should be avoided in patients with a prolonged QT and should be used with caution in those with severe heart failure (left ventricular ejection fraction < 20% and/or New York Heart Association classification ≥ 3) or renal failure. Although sotalol was most commonly tested in randomized trials without concomitant use of other β-blocker therapy,
      • Connolly S.J.
      • Dorian P.
      • Roberts R.S.
      • et al.
      Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
      ,
      • Pacifico A.
      • Hohnloser S.H.
      • Williams J.H.
      • et al.
      Prevention of implantable-defibrillator shocks by treatment with sotalol. d,l-Sotalol Implantable Cardioverter-Defibrillator Study Group.
      consideration can be given to using sotalol in conjunction with an evidence-based β-blocker (carvedilol, bisoprolol, metoprolol succinate, nebivolol)
      • Ezekowitz J.A.
      • O’Meara E.
      • McDonald M.A.
      • et al.
      2017 Comprehensive update of the Canadian Cardiovascular Society Guidelines for the management of heart failure.
      for patients with heart failure and reduced ejection fraction.
      Table 1First-line class III antiarrhythmic drugs for suppression of VT/VF in structural heart disease
      DrugStarting doseTarget doseCautionMonitoringCommon and severe effects
      Sotalol40-80 mg BID120-160 mg BIDBaseline prolonged QT
      • > 450 msec with normal QRS
      • > 480 msec with bundle branch block
      Renal failure:
      • GFR 30-60: reduce dose and consider once-daily dosing
      • GFR < 30: contraindicated
      Advanced heart failure (NYHA ≥ 3 and/or LVEF < 20%)
      • Use with caution
      Body weight ≤ 60 kg
      Laboratory
      • Renal function: GFR baseline and every 6 months
      ECG: (QT monitoring)
      • Baseline, 5-7 days after starting and every 6 months
      • Reduce dose or stop if QTc ≥ 500 msec
      Fatigue

      Bradycardia (sinus bradycardia or atrial fibrillation with slow ventricular response)

      Dizziness/hypotension

      Proarrhythmia (prolonged QT with torsade de pointes)
      AmiodaroneInitial dose:

      400 mg BID for 14 days (consider 400 mg TID for 8 days in inpatients)

      Maintenance dose:

      200 mg daily
      200-400 mg dailyConcomitant digoxin administration (amiodarone increases serum digoxin concentration)

      Concomitant warfarin
      • Amiodarone potentiates warfarin
      • Reduce warfarin dose by 20%-30% when starting amiodarone and monitor INR frequently
      Laboratory:
      • Liver enzymes and thyroid function (TSH) baseline and every 6 months
      ECG:
      • Baseline
      Chest x-ray:
      • Baseline if preexisting lung disease and with symptoms
      Pulmonary function testing
      • Baseline for those with preexisting lung disease
      Ophthalmologic evaluation:
      • Baseline if existing visual impairment and with symptoms
      Skin (photosensitivity)

      Ataxia/tremor

      Visual changes

      Nausea or diarrhea (particularly with loading dose)

      Constipation

      Bradycardia (sinus bradycardia or atrial fibrillation with slow ventricular response)

      Hyperthyroidism

      Hypothyroidism

      Amiodarone blocks the tubular secretion of creatinine by p-glycoprotein. This reduces the total clearance of creatinine resulting in a 5%-15% increase in serum creatinine concentrations in patients who start amiodarone therapy.
      Increased creatinine

      Pulmonary toxicity (pneumonitis or fibrosis—typically with long-term use)

      Liver toxicity
      BID, twice per day; ECG, electrocardiogram; GFR, glomerular filtration rate; INR, international normalized ratio; LVEF, left ventricular ejection fraction; NYHA, New York Heart Association; TID, 3 times per day; TSH, thyroid stimulating hormone; VF, ventricular fibrillation; VT, ventricular tachycardia.
      Amiodarone blocks the tubular secretion of creatinine by p-glycoprotein. This reduces the total clearance of creatinine resulting in a 5%-15% increase in serum creatinine concentrations in patients who start amiodarone therapy.

      7.3 Amiodarone

      Amiodarone is the most effective AAD for reducing VT/VF recurrence in patients with SHD and an ICD.
      • Connolly S.J.
      • Dorian P.
      • Roberts R.S.
      • et al.
      Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
      It requires approximately 10 g (I.V.) to 20 g (oral) dose to achieve steady state and full antiarrhythmic effect (Table 1). Its main limitation is the risk of long-term adverse effects. The discontinuation rate for amiodarone at 1 year is approximately 10%-20%, and increases with time.
      • Connolly S.J.
      • Dorian P.
      • Roberts R.S.
      • et al.
      Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
      ,
      • Sapp J.L.
      • Wells G.A.
      • Parkash R.
      • et al.
      Ventricular tachycardia ablation versus escalation of antiarrhythmic drugs.
      • 9.
        If AAD therapy is chosen for suppressive therapy, we recommend that either sotalol or amiodarone be used as first-line AAD therapy for suppression of VT/VF in patients with SHD (Strong Recommendation, High-Quality Evidence).
      Values and preferences. Although amiodarone is more effective in suppressing VT/VF compared with sotalol, it is associated with long-term toxicities, hence both agents are reasonable as first-line therapy. Each appears to be relatively safe in patients with SHD.
      Practical tip. Sotalol, given its more favourable long-term toxicity profile, should be preferentially used. Sotalol can be used alone or in addition to preexisting β-blocker therapy. However, amiodarone should be used for the treatment of electrical storm, because of its superior efficacy. See Supplemental Table S3 for guidance on drug selection and dosing.

      8. Catheter Ablation for the Treatment of Sustained VT in Patients With SHD

      8.1 Patient selection

      Catheter ablation is effective for patients with monomorphic VT and SHD. Procedural success is generally highest for patients with hemodynamically tolerated monomorphic VT and those with higher left ventricular ejection fraction,
      • Kuck K.H.
      • Schaumann A.
      • Eckardt L.
      • et al.
      Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial.
      ,
      • Callans D.J.
      • Zado E.
      • Sarter B.H.
      • et al.
      Efficacy of radiofrequency catheter ablation for ventricular tachycardia in healed myocardial infarction.
      although substrate ablation techniques have improved ablation effectiveness in patients with worse ventricular systolic function.
      • Di Biase L.
      • Burkhardt J.D.
      • Lakkireddy D.
      • et al.
      Ablation of stable VTs versus substrate ablation in ischemic cardiomyopathy: the VISTA randomized multicenter trial.
      ,
      • Joza J.
      • Nascimento T.
      • Pegoraro V.
      • et al.
      Substrate-guided ablation of haemodynamically tolerated and untolerated ventricular tachycardia in patients with structural heart disease: effect of cardiomyopathy type and acute success on long-term outcome.
      There is a wide spectrum of SHD that leads to scar-related VT. Distribution, location, and heterogeneity of the underlying scar tissue are important determinants of procedural outcomes.

      8.1.1 Ischemic cardiomyopathy

      A randomized study in patients who have refractory monomorphic VT despite AAD therapy showed that catheter ablation is more effective than escalation of AAD therapy, particularly after failure of amiodarone treatment.
      • Sapp J.L.
      • Wells G.A.
      • Parkash R.
      • et al.
      Ventricular tachycardia ablation versus escalation of antiarrhythmic drugs.
      Catheter ablation may be considered for first-line suppressive therapy,
      • Kuck K.H.
      • Schaumann A.
      • Eckardt L.
      • et al.
      Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial.
      ,
      • Reddy V.Y.
      • Reynolds M.R.
      • Neuzil P.
      • et al.
      Prophylactic catheter ablation for the prevention of defibrillator therapy.
      to reduce recurrent subsequent ICD therapies, although randomized comparisons with AADs in this setting are still under way.
      • 10.
        We suggest that catheter ablation can be considered, in selected patients, as first-line suppressive therapy, in addition to β-blocker therapy, for patients with ischemic cardiomyopathy (previous MI) and monomorphic VT (Conditional Recommendation, Low-Quality Evidence).
      Values and preferences. Catheter ablation, using an endocardial approach, has a low risk of complications and good efficacy for monomorphic VT suppression in ischemic cardiomyopathy. Furthermore, it avoids the side effects and long-term risks of AAD therapy.
      Practical tip. First-line catheter ablation should be performed by skilled teams at centres that routinely perform VT ablation.
      • 11.
        We recommend catheter ablation of monomorphic VT in patients with ischemic cardiomyopathy (previous MI) in whom treatment with sotalol or amiodarone has been ineffective (Strong Recommendation, High-Quality Evidence).
      Values and preferences. Catheter ablation has good efficacy at suppressing monomorphic VT in this population, and has a low risk of procedural complications.
      Practical tip. After failure of amiodarone treatment, catheter ablation appears to be much more effective than escalation of AAD therapy (increasing the AAD dose, switching from sotalol to amiodarone, or combination AAD therapy).

      8.1.2 Nonischemic cardiomyopathy

      Nonischemic cardiomyopathies include a heterogeneous group of cardiac diseases with heterogeneous myocardial scar distribution. There are limited data regarding the relative efficacy of catheter ablation or AAD therapy in such patients.
      • Mahida S.
      • Venlet J.
      • Saguner A.M.
      • et al.
      Ablation compared with drug therapy for recurrent ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy: results from a multicenter study.
      Long-term success rates for ablation of monomorphic VT appear more modest compared with those in patients with ischemic cardiomyopathy (Supplemental Table S4), with a frequent need for epicardial ablation.
      • Soejima K.
      • Stevenson W.G.
      • Sapp J.L.
      • et al.
      Endocardial and epicardial radiofrequency ablation of ventricular tachycardia associated with dilated cardiomyopathy: the importance of low-voltage scars.
      ,
      • AbdelWahab A.
      • Gardner M.
      • Parkash R.
      • Gray C.
      • Sapp J.
      Ventricular tachycardia ablation in arrhythmogenic right ventricular cardiomyopathy patients with TMEM43 gene mutations.
      Accordingly, there is a higher threshold for the use of catheter ablation in this population.
      • 12.
        We recommend catheter ablation of monomorphic VT in patients with nonischemic cardiomyopathy in whom treatment with sotalol or amiodarone has been ineffective (Strong Recommendation, Low-Quality Evidence).
      Values and preferences. The reduced efficacy of catheter ablation, and the increased complexity of the procedure in patients with nonischemic cardiomyopathies led to the recommendation that catheter ablation should be considered second-line in this population.
      Practical tip. Catheter ablation in patients with nonischemic cardiomyopathy should be performed by skilled teams at centres that routinely perform VT ablation, including experience with epicardial ablation.

      8.1.3 Epicardial mapping and ablation

      Percutaneous epicardial access facilitates mapping and ablation of epicardial myocardial substrate, but is associated with added risks. Epicardial mapping should be considered in patients in whom previous endocardial catheter ablation has failed and an epicardial substrate is suspected.
      • Sosa E.
      • Scanavacca M.
      • d’Avila A.
      • Oliveira F.
      • Ramires J.A.
      Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction.
      • Schmidt B.
      • Chun K.R.
      • Baensch D.
      • et al.
      Catheter ablation for ventricular tachycardia after failed endocardial ablation: epicardial substrate or inappropriate endocardial ablation?.
      • Garcia F.C.
      • Bazan V.
      • Zado E.S.
      • Ren J.F.
      • Marchlinski F.E.
      Epicardial substrate and outcome with epicardial ablation of ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy/dysplasia.
      • Pokushalov E.
      • Romanov A.
      • Turov A.
      • et al.
      Percutaneous epicardial ablation of ventricular tachycardia after failure of endocardial approach in the pediatric population with arrhythmogenic right ventricular dysplasia.
      Epicardial mapping during the first ablation procedure should be reserved for patients with ARVC or dilated cardiomyopathy, who commonly have an epicardial VT substrate.
      • Berruezo A.
      • Acosta J.
      • Fernandez-Armenta J.
      • et al.
      Safety, long-term outcomes and predictors of recurrence after first-line combined endoepicardial ventricular tachycardia substrate ablation in arrhythmogenic cardiomyopathy. Impact of arrhythmic substrate distribution pattern. A prospective multicentre study.
      • Santangeli P.
      • Zado E.S.
      • Supple G.E.
      • et al.
      Long-term outcome with catheter ablation of ventricular tachycardia in patients with arrhythmogenic right ventricular cardiomyopathy.
      • Bai R.
      • Di Biase L.
      • Shivkumar K.
      • et al.
      Ablation of ventricular arrhythmias in arrhythmogenic right ventricular dysplasia/cardiomyopathy: arrhythmia-free survival after endo-epicardial substrate based mapping and ablation.
      • Della Bella P.
      • Brugada J.
      • Zeppenfeld K.
      • et al.
      Epicardial ablation for ventricular tachycardia: a European multicenter study.
      • Cano O.
      • Hutchinson M.
      • Lin D.
      • et al.
      Electroanatomic substrate and ablation outcome for suspected epicardial ventricular tachycardia in left ventricular nonischemic cardiomyopathy.

      8.2 Complications

      Catheter ablation of VT in patients with SHD is a complex procedure performed in a vulnerable patient. The procedure carries significant risks, which can be minimized with experience, technique, and patient optimization. In contemporary trials, reported procedural complication rates have been between 3% and 6%.
      • Kuck K.H.
      • Schaumann A.
      • Eckardt L.
      • et al.
      Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial.
      ,
      • Sapp J.L.
      • Wells G.A.
      • Parkash R.
      • et al.
      Ventricular tachycardia ablation versus escalation of antiarrhythmic drugs.
      ,
      • Di Biase L.
      • Burkhardt J.D.
      • Lakkireddy D.
      • et al.
      Ablation of stable VTs versus substrate ablation in ischemic cardiomyopathy: the VISTA randomized multicenter trial.
      ,
      • Reddy V.Y.
      • Reynolds M.R.
      • Neuzil P.
      • et al.
      Prophylactic catheter ablation for the prevention of defibrillator therapy.
      ,
      • Tzou W.S.
      • Tung R.
      • Frankel D.S.
      • et al.
      Ventricular tachycardia ablation in severe heart failure.
      One analysis of administrative data suggested an acute complication rate of 9.9% and in-hospital mortality of 1.8%.
      • Hosseini S.M.
      • Rozen G.
      • Saleh A.
      • et al.
      Catheter ablation for cardiac arrhythmias
      Utilization and in-hospital complications, 2000 to 2013.

      9. ICD Programming in Patients With Sustained VT/VF in the Setting of SHD

      The goals of ICD programming are to ensure appropriate therapy for VT/VF, to minimize inappropriate shocks, to minimize symptoms from VT/VF, and to prevent mortality (Table 2). Secondary goals include avoidance of arrhythmia induction and of nonessential therapies.
      • Ruwald A.C.
      • Schuger C.
      • Moss A.J.
      • et al.
      Mortality reduction in relation to implantable cardioverter defibrillator programming in the Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT).
      ,
      • Sterns L.D.
      • Meine M.
      • Kurita T.
      • et al.
      Extended detection time to reduce shocks is safe in secondary prevention patients: the secondary prevention substudy of PainFree SST.
      ICD shocks are associated with increased mortality, hospitalization, and health care costs compared with ATP therapy alone.
      • Ruwald A.C.
      • Schuger C.
      • Moss A.J.
      • et al.
      Mortality reduction in relation to implantable cardioverter defibrillator programming in the Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT).
      ,
      • Sanders P.
      • Connolly A.T.
      • Nabutovsky Y.
      • Fischer A.
      • Saeed M.
      Increased hospitalizations and overall healthcare utilization in patients receiving implantable cardioverter-defibrillator shocks compared with antitachycardia pacing.
      Table 2Suggested ICD programming for patients with sustained VT/VF
      ZoneRate cutoffDetection intervals/timeTherapy
      VF> 250 BPM (240 msec)Medtronic: 30/40 intervals

      Abbott: 30 intervals

      Boston Scientific: 2.5 s

      Biotronik: 30/40 intervals

      MicroPort CRM: 20 cycles, 6/8 majority
      Shocks with ATP during charge
      Fast VT188-250 BPM (320-240 msec)Medtronic: 30/40 intervals

      Abbott: 30 intervals

      Boston Scientific: 12 s

      Biotronik: 30 intervals

      MicroPort CRM: 20 cycles, 6/8 majority
      1-4 ATP bursts followed by shocks
      Slow VT10-20 BPM slower than slowest documented VT
      Twenty BPM slower favoured if VT rate ≥ 150 BPM or if amiodarone initiated for the treatment of VT.
      Medtronic: 32-36 intervals

      Abbott: 30 intervals

      Boston Scientific: 60 s

      Biotronik: 30 intervals

      MicroPort CRM: 30 cycles, 6/8 majority
      ATP predominant

      Shocks are optional and may be omitted for slow VT
      ATP, antitachycardia pacing; BPM, beats per minute; CRM, cardiac rhythm management; ICD, implantable cardioverter-defibrillator; VF, ventricular fibrillation; VT, ventricular tachycardia.
      Twenty BPM slower favoured if VT rate ≥ 150 BPM or if amiodarone initiated for the treatment of VT.
      In patients with VT/VF, prolonged detection times reduce inappropriate therapy and nonessential appropriate therapy, with no increase in mortality or arrhythmic syncope.
      • Sterns L.D.
      • Meine M.
      • Kurita T.
      • et al.
      Extended detection time to reduce shocks is safe in secondary prevention patients: the secondary prevention substudy of PainFree SST.
      ,
      • Kloppe A.
      • Proclemer A.
      • Arenal A.
      • et al.
      Efficacy of long detection interval implantable cardioverter-defibrillator settings in secondary prevention population: data from the Avoid Delivering Therapies for Nonsustained Arrhythmias in ICD Patients III (ADVANCE III) trial.
      ,
      • Mastenbroek M.H.
      • Pedersen S.S.
      • van der Tweel I.
      • Doevendans P.A.
      • Meine M.
      Results of ENHANCED implantable cardioverter defibrillator programming to reduce therapies and improve quality of life (from the ENHANCED-ICD Study).
      Numerous trials support the use of ATP programming for fast VT (188-250 beats per minute).
      • Saeed M.
      • Neason C.G.
      • Razavi M.
      • et al.
      Programming antitachycardia pacing for primary prevention in patients with implantable cardioverter defibrillators: results from the PROVE trial.
      • Wathen M.S.
      • DeGroot P.J.
      • Sweeney M.O.
      • et al.
      Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators: pacing fast ventricular tachycardia reduces shock therapies (PainFREE Rx II) trial results.
      • Santini M.
      • Lunati M.
      • Defaye P.
      • et al.
      Prospective multicenter randomized trial of fast ventricular tachycardia termination by prolonged versus conventional anti-tachyarrhythmia burst pacing in implantable cardioverter-defibrillator patients-Atp DeliVery for pAiNless ICD thErapy (ADVANCE-D) trial results.

      10. Suppression of VT/VF When Initial Therapy Is Ineffective (Second- and Third-Line Therapy)

      Initial suppressive therapies for VT/VF in patients with SHD are sotalol, amiodarone, or catheter ablation. After failure of one of these therapies, a trial of an alternate first-line therapy should be undertaken. Amiodarone and catheter ablation have similar efficacy after failure of sotalol treatment.
      • Sapp J.L.
      • Wells G.A.
      • Parkash R.
      • et al.
      Ventricular tachycardia ablation versus escalation of antiarrhythmic drugs.
      A significant proportion of patients will have recurrent VT/VF despite first-line therapy, and alternate strategies must be considered.

      10.1 Second- and third-line antiarrhythmic therapy

      10.1.1 Mexiletine

      Mexiletine, a class I AAD with properties similar to I.V. lidocaine, has been reported in small cohort studies to have some efficacy in combination with amiodarone.
      • Gao D.
      • Van Herendael H.
      • Alshengeiti L.
      • et al.
      Mexiletine as an adjunctive therapy to amiodarone reduces the frequency of ventricular tachyarrhythmia events in patients with an implantable defibrillator.
      ,
      • Hoffmann A.
      • Follath F.
      • Burckhardt D.
      Safe treatment of resistant ventricular arrhythmias with a combination of amiodarone and quinidine or mexiletine.
      Nevertheless, the additional use of mexiletine with high-dose amiodarone (> 300 mg daily) is inferior to catheter ablation.
      • Deyell M.W.
      • Steinberg C.
      • Doucette S.
      • et al.
      Mexiletine or catheter ablation after amiodarone failure in the VANISH trial.
      A pre-ICD era randomized trial of mexiletine showed increased mortality when used in patients with heart failure.
      International mexiletine and placebo antiarrhythmic coronary trial: I. Report on arrhythmia and other findings. Impact Research Group.
      Thus mexiletine should be used with caution in patients with SHD and heart failure.

      10.1.2 Dofetilide (not currently available in Canada)

      Dofetilide prolongs repolarization and has a risk of QT prolongation and proarrhythmia. However, it as been shown to reduce VT/VF and ICD shocks in cohort studies.
      • Pinter A.
      • Akhtari S.
      • O’Connell T.
      • et al.
      Efficacy and safety of dofetilide in the treatment of frequent ventricular tachyarrhythmias after amiodarone intolerance or failure.
      ,
      • Baquero G.A.
      • Banchs J.E.
      • Depalma S.
      • et al.
      Dofetilide reduces the frequency of ventricular arrhythmias and implantable cardioverter defibrillator therapies.
      In a cross-over study, dofetilide had efficacy similar to sotalol.
      • Boriani G.
      • Lubinski A.
      • Capucci A.
      • et al.
      A multicentre, double-blind randomized crossover comparative study on the efficacy and safety of dofetilide vs sotalol in patients with inducible sustained ventricular tachycardia and ischaemic heart disease.
      However, many patients who responded to one drug did not respond to the other.

      10.1.3 Class 1C agents

      Class 1C agents might lead to increased mortality risk in patients with ventricular scar/dysfunction (in the absence of an ICD).
      • Echt D.S.
      • Liebson P.R.
      • Mitchell L.B.
      • et al.
      Mortality and morbidity in patients receiving encainide, flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial.
      However, case series have reported successful combination therapy using sotalol and flecainide in patients with ARVC who had preserved left ventricular ejection fraction and refractory VT.
      • Ermakov S.
      • Hoffmayer K.S.
      • Gerstenfeld E.P.
      • Scheinman M.M.
      Combination drug therapy for patients with intractable ventricular tachycardia associated with right ventricular cardiomyopathy.
      ,
      • Bouvier F.
      • Maupain C.
      • Roche N.C.
      • et al.
      Effectiveness and safety of flecainide in arrhythmogenic right ventricular cardiomyopathy. Archives of Cardiovascular Diseases.
      • 13.
        We suggest that mexiletine (given in addition to amiodarone) or dofetilide can be used in patients with SHD and refractory VT/VF who are not candidates or in whom therapy with sotalol, amiodarone, or catheter ablation has failed (Conditional Recommendation, Low-Quality Evidence).
      Values and preferences. Despite the lack of evidence supporting the use of mexiletine and dofetilide, there are few other therapeutic alternatives in this setting.
      Practical tip. Mexiletine has limited efficacy as monotherapy and should be given in addition to amiodarone. Dofetilide can be given as monotherapy.

      10.2 Emerging and alternate ablation modalities

      Several newer ablation approaches have been used for treatment-refractory monomorphic VT, including needle ablation, bipolar ablation, transvascular ethanol, and stereotactic radiotherapy. Each permits ablation of deep substrate, not easily reached from the endocardium.
      • Koruth J.S.
      • Dukkipati S.
      • Miller M.A.
      • et al.
      Bipolar irrigated radiofrequency ablation: a therapeutic option for refractory intramural atrial and ventricular tachycardia circuits.
      • Robinson C.G.
      • Samson P.P.
      • Moore K.M.S.
      • et al.
      Phase I/II trial of electrophysiology-guided noninvasive cardiac radioablation for ventricular tachycardia.
      • Sacher F.
      • Sobieszczyk P.
      • Tedrow U.
      • et al.
      Transcoronary ethanol ventricular tachycardia ablation in the modern electrophysiology era.
      • Sapp J.L.
      • Beeckler C.
      • Pike R.
      • et al.
      Initial human feasibility of infusion needle catheter ablation for refractory ventricular tachycardia.

      10.3 Cardiac sympathectomy

      There is increasing evidence for the use of bilateral cardiac sympathetic denervation for the acute and long-term management of refractory VT/VF in patients with SHD.
      • Vaseghi M.
      • Barwad P.
      • Malavassi Corrales F.J.
      • et al.
      Cardiac sympathetic denervation for refractory ventricular arrhythmias.
      This procedure is carried out via thorascopic surgery in a single or staged procedure.
      • 14.
        We suggest that bipolar radiofrequency ablation, extendable/retractable radiofrequency needle ablation, stereotactic ablative radiotherapy, and sympathectomy may be considered for treatment of VT/VF after failure of one or more standard ablation procedures and after failure of amiodarone therapy (Conditional Recommendation, Low-Quality Evidence).
      Values and preferences. Most of these techniques are emerging therapies, with sympathectomy having the most supporting evidence. Despite the limited data supporting these techniques, they might be beneficial in patients with refractory VT/VF.
      Practical tip. These techniques should be used, by experienced operators, and preferably in the context of a research protocol.

      11. Psychosocial Care of Patients With VT/VF

      Studies of the roles of psychosocial factors in the genesis and management of VT/VF are appearing with increasing frequency. Individuals experiencing VT/VF might be susceptible to poor mental health and reduced quality of life as they manage the symptoms of the VT/VF and those of its treatment.

      11.1 Preimplantation and stable postimplantation patients

      Anxiety and depression are prevalent among patients with an ICD and particularly those who have experienced VT/VF.
      • Dunbar S.B.
      • Dougherty C.M.
      • Sears S.F.
      • et al.
      Educational and psychological interventions to improve outcomes for recipients of implantable cardioverter defibrillators and their families: a scientific statement from the American Heart Association.
      Preimplantation factors that contribute to this psychological distress include: premorbid psychological distress, ICD concerns, reduced perceived control, and type D (distressed) personality.
      • Pedersen S.S.
      • van den Broek K.C.
      • Erdman R.A.
      • Jordaens L.
      • Theuns D.A.
      Pre-implantation implantable cardioverter defibrillator concerns and type D personality increase the risk of mortality in patients with an implantable cardioverter defibrillator.
      These factors place the patient at increased risk of complications/difficulties post implantation and at increased risk of mortality. Unfortunately, these symptoms often go undetected and untreated.
      Optimal care pathways should include screening and treatment for psychological distress among patients with VT/VF and an ICD to safeguard health status. Managing psychological distress while living with an ICD is essential to improve outcomes.
      In patients with VT/VF and SHD, special attention should be directed to reducing ICD shocks, because they are a significant cause of anxiety due to anticipation of shocks and associated pain.
      • Perini A.P.
      • Kutyifa V.
      • Veazie P.
      • et al.
      Effects of implantable cardioverter/defibrillator shock and antitachycardia pacing on anxiety and quality of life: a MADIT-RIT substudy.
      The fear of shocks can have as much or more psychological effect on a patient as an actual shock.
      • Thylen I.
      • Moser D.K.
      • Stromberg A.
      • Dekker R.A.
      • Chung M.L.
      Concerns about implantable cardioverter-defibrillator shocks mediate the relationship between actual shocks and psychological distress.
      • 15.
        We recommend frequent systematic assessment of psychological status in all patients with SHD and VT/VF, and recommend referral for treatment of such distress when identified (Strong Recommendation, Low-Quality Evidence).
      Values and preferences. The psychological effect of VT/VF and its therapies is substantial and can affect all facets of a patient’s life. This effect might not be fully appreciated in routine care discussions and needs to be explicitly evaluated.
      Practical tip. Simple screening tools, such as the Patient Health Questionnaire-2 (PHQ-2) and the Generalized Anxiety Disorder-2 (GAD-2) questionnaire are an effective way to screen psychological status (see the Psychological Status Screening Tools section of the Supplementary Material). If either of these are positive (score ≥ 3), a more in-depth assessment of psychological status is warranted.

      11.2 Special populations; ICD generator change in frail/elderly patients

      Patients might develop new or worsening illness subsequent to their initial ICD implantation and their goals of care might change to favour comfort over longevity. A significant proportion of these patients might be unaware of the option of deactivation of tachycardia therapy. Furthermore, they might overestimate the potential benefits of the ICD near the end of life, particularly as the risk of nonarrhythmic death increases (such as in advanced heart failure).
      • Thylen I.
      • Moser D.K.
      • Stromberg A.
      • Dekker R.A.
      • Chung M.L.
      Concerns about implantable cardioverter-defibrillator shocks mediate the relationship between actual shocks and psychological distress.

      11.3 End of life

      The management of VT/VF at the end of life can be associated with significant patient and family distress. Clinicians need to ensure that patients are aware that deactivation of ICD tachyarrhythmia therapies is an option at any time, and is not akin to euthanasia,
      • Kelley A.S.
      • Reid M.C.
      • Miller D.H.
      • Fins J.J.
      • Lachs M.S.
      Implantable cardioverter-defibrillator deactivation at the end of life: a physician survey.
      and will not lead to immediate death.
      • Kirkpatrick J.N.
      • Gottlieb M.
      • Sehgal P.
      • Patel R.
      • Verdino R.J.
      Deactivation of implantable cardioverter defibrillators in terminal illness and end of life care.
      These conversations are best carried out before ICD implantation, continued on a regular basis as part of routine device care, and then revisited at times of significant clinical decline.
      • McEvedy S.M.
      • Cameron J.
      • Lugg E.
      • et al.
      Implantable cardioverter defibrillator knowledge and end-of-life device deactivation: a cross-sectional survey.
      ICD deactivation near the end of life can potentially minimize physical and psychological distress. Although patients might choose to maintain ICD therapies near the time of death, it is important to ensure that such patients have made well informed decisions in line with their goals of care.
      • Lampert R.
      Implantable cardioverter-defibrillator shocks in dying patients: disturbing data from beyond the grave.
      • 16.
        In patients with VT/VF, we recommend ongoing incorporation of patient values and preferences in goals of care discussions, including ICD tachycardia therapy deactivation or ICD replacement with a pacemaker, particularly at times of ICD generator replacement or changes in clinical status (Strong Recommendation, Low-Quality Evidence).
      Values and preferences. Despite the lack of systematic evidence supporting goals of care discussions, the importance of these discussions is paramount for patient-centred care.
      Practical tip. Incorporating discussion of goals of care and ICD deactivation into routine device clinic standard of care promotes enhanced patient understanding of end of life options and facilitates patient decision-making.

      12. Conclusion/Future Directions/Knowledge Gaps

      Implantable defibrillators have dramatically modified the prognosis and the management of ventricular arrhythmias in the presence of SHD. Further study is needed to minimize sudden death risk in the population, to understand when and which arrhythmia-suppressive therapy is best, and to understand the short-and long-term clinical outcomes of available therapies, as well as their effects on mortality, cost-effectiveness, and quality of life.

      Funding Sources

      This position statement was funded by the Canadian Cardiovascular Society .

      Disclosures

      Please see Supplemental Table S1 for a complete list of disclosures.

      Acknowledgements

      The authors thank Brittany Forrest from the Canadian Cardiovascular Society for her tireless efforts.
      Members of the Secondary Panel who contributed to this work are: Eugene Crystal, MD (Schulich Heart Centre, Sunnybrook Health Sciences); Paul Dorian, MD (St Michael’s Hospital, University of Toronto); Jaqueline Joza, MD (Division of Cardiology, McGill University Health Centre, Montreal Quebec); Vikas P. Kuriachan, MD (Libin Cardiovascular Institute of Alberta, University of Calgary); Peter Leong-Sit, MD (Western University); and P. Timothy Pollack, MD (Libin Cardiovascular Institute of Alberta, University of Calgary).

      Supplementary Material

      References

        • Bennett M.
        • Parkash R.
        • Nery P.
        • et al.
        Canadian Cardiovascular Society/Canadian Heart Rhythm Society 2016 implantable cardioverter-defibrillator guidelines.
        Can J Cardiol. 2017; 33: 174-188
        • Khairy P.
        Arrhythmias in adults with congenital heart disease: what the practicing cardiologist needs to know.
        Can J Cardiol. 2019; 35: 1698-1707
        • Khairy P.
        • Van Hare G.F.
        • Balaji S.
        • et al.
        PACES/HRS expert consensus statement on the recognition and management of arrhythmias in adult congenital heart disease: developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American College of Cardiology (ACC), the American Heart Association (AHA), the European Heart Rhythm Association (EHRA), the Canadian Heart Rhythm Society (CHRS), and the International Society for Adult Congenital Heart Disease (ISACHD).
        Heart Rhythm. 2014; 11: e102-e165
        • Neumar R.W.
        • Shuster M.
        • Callaway C.W.
        • et al.
        Part 1: executive summary: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care.
        Circulation. 2015; 132: S315-S367
        • Buxton A.E.
        • Calkins H.
        • Callans D.J.
        • et al.
        ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards (ACC/AHA/HRS Writing Committee to Develop Data Standards on Electrophysiology).
        J Am Coll Cardiol. 2006; 48: 2360-2396
        • Kuck K.H.
        • Cappato R.
        • Siebels J.
        • Ruppel R.
        Randomized comparison of antiarrhythmic drug therapy with implantable defibrillators in patients resuscitated from cardiac arrest : the Cardiac Arrest Study Hamburg (CASH).
        Circulation. 2000; 102: 748-754
        • Bunch T.J.
        • White R.D.
        Trends in treated ventricular fibrillation in out-of-hospital cardiac arrest: ischemic compared to non-ischemic heart disease.
        Resuscitation. 2005; 67: 51-54
        • Sweeney M.O.
        • Sherfesee L.
        • DeGroot P.J.
        • Wathen M.S.
        • Wilkoff B.L.
        Differences in effects of electrical therapy type for ventricular arrhythmias on mortality in implantable cardioverter-defibrillator patients.
        Heart Rhythm. 2010; 7: 353-360
        • Neilan T.G.
        • Farhad H.
        • Mayrhofer T.
        • et al.
        Late gadolinium enhancement among survivors of sudden cardiac arrest.
        JACC Cardiovasc Imaging. 2015; 8: 414-423
        • White J.A.
        • Fine N.M.
        • Gula L.
        • et al.
        Utility of cardiovascular magnetic resonance in identifying substrate for malignant ventricular arrhythmias.
        Circ Cardiovasc Imaging. 2012; 5: 12-20
        • Chareonthaitawee P.
        • Beanlands R.S.
        • Chen W.
        • et al.
        Joint SNMMI–ASNC expert consensus document on the role of 18F-FDG PET/CT in cardiac sarcoid detection and therapy monitoring.
        J Nucl Med. 2017; 58: 1341-1353
        • Balasundaram R.
        • Rao H.B.
        • Kalavakolanu S.
        • Narasimhan C.
        Catheter ablation of bundle branch reentrant ventricular tachycardia.
        Heart Rhythm. 2008; 5: S68-72
        • Panchal A.R.
        • Berg K.M.
        • Kudenchuk P.J.
        • et al.
        2018 American Heart Association focused update on advanced cardiovascular life support use of antiarrhythmic drugs during and immediately after cardiac arrest: an update to the American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care.
        Circulation. 2018; 138: e740-e749
        • Link M.S.
        • Berkow L.C.
        • Kudenchuk P.J.
        • et al.
        Part 7: adult advanced cardiovascular life support: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care.
        Circulation. 2015; 132: S444-S464
        • Kudenchuk P.J.
        • Brown S.P.
        • Daya M.
        • et al.
        Amiodarone, lidocaine, or placebo in out-of-hospital cardiac arrest.
        N Engl J Med. 2016; 374: 1711-1722
        • Dorian P.
        • Cass D.
        • Schwartz B.
        • et al.
        Amiodarone as compared with lidocaine for shock-resistant ventricular fibrillation.
        N Engl J Med. 2002; 346: 884-890
        • Chatzidou S.
        • Kontogiannis C.
        • Tsilimigras D.I.
        • et al.
        Propranolol versus metoprolol for treatment of electrical storm in patients with implantable cardioverter-defibrillator.
        J Am Coll Cardiol. 2018; 71: 1897-1906
        • Mulpuru S.K.
        • Patel D.V.
        • Wilbur S.L.
        • Vasavada B.C.
        • Furqan T.
        Electrical storm and termination with propofol therapy: a case report.
        Int J Cardiol. 2008; 128: e6-8
        • Parent B.A.
        • Munoz R.
        • Shiderly D.
        • Chrysostomou C.
        Use of dexmedetomidine in sustained ventricular tachycardia.
        Anaesth Intensive Care. 2010; 38: 781
        • Kowey P.R.
        • Levine J.H.
        • Herre J.M.
        • et al.
        Randomized, double-blind comparison of intravenous amiodarone and bretylium in the treatment of patients with recurrent, hemodynamically destabilizing ventricular tachycardia or fibrillation. The Intravenous Amiodarone Multicenter Investigators Group.
        Circulation. 1995; 92: 3255-3263
        • Levine J.H.
        • Massumi A.
        • Scheinman M.M.
        • et al.
        Intravenous amiodarone for recurrent sustained hypotensive ventricular tachyarrhythmias. Intravenous Amiodarone Multicenter Trial Group.
        J Am Coll Cardiol. 1996; 27: 67-75
        • Komatsu Y.
        • Hocini M.
        • Nogami A.
        • et al.
        Catheter ablation of refractory ventricular fibrillation storm after myocardial infarction.
        Circulation. 2019; 139: 2315-2325
        • Vergara P.
        • Tung R.
        • Vaseghi M.
        • et al.
        Successful ventricular tachycardia ablation in patients with electrical storm reduces recurrences and improves survival.
        Heart Rhythm. 2018; 15: 48-55
        • Nagpal A.D.
        • Singal R.K.
        • Arora R.C.
        • Lamarche Y.
        Temporary mechanical circulatory support in cardiac critical care: a state of the art review and algorithm for device selection.
        Can J Cardiol. 2017; 33: 110-118
        • Ortiz M.
        • Martin A.
        • Arribas F.
        • et al.
        Randomized comparison of intravenous procainamide vs. intravenous amiodarone for the acute treatment of tolerated wide QRS tachycardia: the PROCAMIO study.
        Eur Heart J. 2017; 38: 1329-1335
        • deSouza I.S.
        • Martindale J.L.
        • Sinert R.
        Antidysrhythmic drug therapy for the termination of stable, monomorphic ventricular tachycardia: a systematic review.
        Emerg Med J. 2015; 32: 161-167
        • Topol E.J.
        • Lerman B.B.
        Hypomagnesemic torsades de pointes.
        Am J Cardiol. 1983; 52: 1367-1368
        • Roffe C.
        • Fletcher S.
        • Woods K.L.
        Investigation of the effects of intravenous magnesium sulphate on cardiac rhythm in acute myocardial infarction.
        Br Heart J. 1994; 71: 141-145
        • Connolly S.J.
        • Dorian P.
        • Roberts R.S.
        • et al.
        Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial.
        JAMA. 2006; 295: 165-171
        • Pacifico A.
        • Hohnloser S.H.
        • Williams J.H.
        • et al.
        Prevention of implantable-defibrillator shocks by treatment with sotalol. d,l-Sotalol Implantable Cardioverter-Defibrillator Study Group.
        N Engl J Med. 1999; 340: 1855-1862
        • Kuck K.H.
        • Schaumann A.
        • Eckardt L.
        • et al.
        Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial.
        Lancet. 2010; 375: 31-40
        • Dinov B.
        • Arya A.
        • Bertagnolli L.
        • et al.
        Early referral for ablation of scar-related ventricular tachycardia is associated with improved acute and long-term outcomes: results from the Heart Center of Leipzig ventricular tachycardia registry.
        Circ Arrhythm Electrophysiol. 2014; 7: 1144-1151
        • Willems S.
        • Tilz Roland R.
        • Steven D.
        • et al.
        Preventive or deferred ablation of ventricular tachycardia in patients with ischemic cardiomyopathy and implantable defibrillator (BERLIN VT): a multicenter randomized trial.
        Circulation. 2020; 141: 1057-1067
        • Sapp J.L.
        • Wells G.A.
        • Parkash R.
        • et al.
        Ventricular tachycardia ablation versus escalation of antiarrhythmic drugs.
        N Engl J Med. 2016; 375: 111-121
        • Ezekowitz J.A.
        • O’Meara E.
        • McDonald M.A.
        • et al.
        2017 Comprehensive update of the Canadian Cardiovascular Society Guidelines for the management of heart failure.
        Can J Cardiol. 2017; 33: 1342-1433
        • Izquierdo M.
        • Ruiz-Granell R.
        • Ferrero A.
        • et al.
        Ablation or conservative management of electrical storm due to monomorphic ventricular tachycardia: differences in outcome.
        Europace. 2012; 14: 1734-1739
        • Morawski S.
        • Pruszkowska P.
        • Sredniawa B.
        • Lenarczyk R.
        • Kalarus Z.
        Long-term outcome of catheter ablation and other form of therapy for electrical storm in patients with implantable cardioverter-defibrillators.
        J Interv Card Electrophysiol. 2017; 50: 227-234
        • Singh S.N.
        • Fletcher R.D.
        • Fisher S.
        • et al.
        Veterans Affairs congestive heart failure antiarrhythmic trial. CHF STAT Investigators.
        Am J Cardiol. 1993; 72: 99F-102F
        • Cairns J.A.
        • Connolly S.J.
        • Roberts R.
        • Gent M.
        Randomised trial of outcome after myocardial infarction in patients with frequent or repetitive ventricular premature depolarisations: CAMIAT. Canadian Amiodarone Myocardial Infarction Arrhythmia Trial Investigators.
        Lancet. 1997; 349: 675-682
        • Claro J.C.
        • Candia R.
        • Rada G.
        • et al.
        Amiodarone versus other pharmacological interventions for prevention of sudden cardiac death.
        Cochrane Database Syst Rev. 2015; 12: CD008093
        • Ellison K.E.
        • Hafley G.E.
        • Hickey K.
        • et al.
        Effect of beta-blocking therapy on outcome in the Multicenter UnSustained Tachycardia Trial (MUSTT).
        Circulation. 2002; 106: 2694-2699
      1. Effect of metoprolol CR/XL in chronic heart failure: Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF).
        Lancet. 1999; 353: 2001-2007
        • Levine J.H.
        • Mellits E.D.
        • Baumgardner R.A.
        • et al.
        Predictors of first discharge and subsequent survival in patients with automatic implantable cardioverter-defibrillators.
        Circulation. 1991; 84: 558-566
        • Deftereos S.
        • Giannopoulos G.
        • Kossyvakis C.
        • et al.
        Relation of ventricular tachycardia/fibrillation to beta-blocker dose maximization guided by pacing mode analysis in nonpacemaker-dependent patients with implantable cardioverter-defibrillator.
        Am J Cardiol. 2011; 107: 1812-1817
        • Waldo A.L.
        • Camm A.J.
        • deRuyter H.
        • et al.
        Effect of d-sotalol on mortality in patients with left ventricular dysfunction after recent and remote myocardial infarction. The SWORD Investigators. Survival with oral d-sotalol.
        Lancet. 1996; 348: 7-12
        • Callans D.J.
        • Zado E.
        • Sarter B.H.
        • et al.
        Efficacy of radiofrequency catheter ablation for ventricular tachycardia in healed myocardial infarction.
        Am J Cardiol. 1998; 82: 429-432
        • Di Biase L.
        • Burkhardt J.D.
        • Lakkireddy D.
        • et al.
        Ablation of stable VTs versus substrate ablation in ischemic cardiomyopathy: the VISTA randomized multicenter trial.
        J Am Coll Cardiol. 2015; 66: 2872-2882
        • Joza J.
        • Nascimento T.
        • Pegoraro V.
        • et al.
        Substrate-guided ablation of haemodynamically tolerated and untolerated ventricular tachycardia in patients with structural heart disease: effect of cardiomyopathy type and acute success on long-term outcome.
        Europace. 2014; 17: 461-467
        • Reddy V.Y.
        • Reynolds M.R.
        • Neuzil P.
        • et al.
        Prophylactic catheter ablation for the prevention of defibrillator therapy.
        N Engl J Med. 2007; 357: 2657-2665
        • Mahida S.
        • Venlet J.
        • Saguner A.M.
        • et al.
        Ablation compared with drug therapy for recurrent ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy: results from a multicenter study.
        Heart Rhythm. 2019; 16: 536-543
        • Soejima K.
        • Stevenson W.G.
        • Sapp J.L.
        • et al.
        Endocardial and epicardial radiofrequency ablation of ventricular tachycardia associated with dilated cardiomyopathy: the importance of low-voltage scars.
        J Am Coll Cardiol. 2004; 43: 1834-1842
        • AbdelWahab A.
        • Gardner M.
        • Parkash R.
        • Gray C.
        • Sapp J.
        Ventricular tachycardia ablation in arrhythmogenic right ventricular cardiomyopathy patients with TMEM43 gene mutations.
        J Cardiovasc Electrophysiol. 2018; 29: 90-97
        • Sosa E.
        • Scanavacca M.
        • d’Avila A.
        • Oliveira F.
        • Ramires J.A.
        Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction.
        J Am Coll Cardiol. 2000; 35: 1442-1449
        • Schmidt B.
        • Chun K.R.
        • Baensch D.
        • et al.
        Catheter ablation for ventricular tachycardia after failed endocardial ablation: epicardial substrate or inappropriate endocardial ablation?.
        Heart Rhythm. 2010; 7: 1746-1752
        • Garcia F.C.
        • Bazan V.
        • Zado E.S.
        • Ren J.F.
        • Marchlinski F.E.
        Epicardial substrate and outcome with epicardial ablation of ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy/dysplasia.
        Circulation. 2009; 120: 366-375
        • Pokushalov E.
        • Romanov A.
        • Turov A.
        • et al.
        Percutaneous epicardial ablation of ventricular tachycardia after failure of endocardial approach in the pediatric population with arrhythmogenic right ventricular dysplasia.
        Heart Rhythm. 2010; 7: 1406-1410
        • Berruezo A.
        • Acosta J.
        • Fernandez-Armenta J.
        • et al.
        Safety, long-term outcomes and predictors of recurrence after first-line combined endoepicardial ventricular tachycardia substrate ablation in arrhythmogenic cardiomyopathy. Impact of arrhythmic substrate distribution pattern. A prospective multicentre study.
        Europace. 2017; 19: 607-616
        • Santangeli P.
        • Zado E.S.
        • Supple G.E.
        • et al.
        Long-term outcome with catheter ablation of ventricular tachycardia in patients with arrhythmogenic right ventricular cardiomyopathy.
        Circ Arrhythm Electrophysiol. 2015; 8: 1413-1421
        • Bai R.
        • Di Biase L.
        • Shivkumar K.
        • et al.
        Ablation of ventricular arrhythmias in arrhythmogenic right ventricular dysplasia/cardiomyopathy: arrhythmia-free survival after endo-epicardial substrate based mapping and ablation.
        Circ Arrhythm Electrophysiol. 2011; 4: 478-485
        • Della Bella P.
        • Brugada J.
        • Zeppenfeld K.
        • et al.
        Epicardial ablation for ventricular tachycardia: a European multicenter study.
        Circ Arrhythm Electrophysiol. 2011; 4: 653-659
        • Cano O.
        • Hutchinson M.
        • Lin D.
        • et al.
        Electroanatomic substrate and ablation outcome for suspected epicardial ventricular tachycardia in left ventricular nonischemic cardiomyopathy.
        J Am Coll Cardiol. 2009; 54: 799-808
        • Tzou W.S.
        • Tung R.
        • Frankel D.S.
        • et al.
        Ventricular tachycardia ablation in severe heart failure.
        Circ Arrhythm Electrophysiol. 2017; 10e004494
        • Hosseini S.M.
        • Rozen G.
        • Saleh A.
        • et al.
        • Catheter ablation for cardiac arrhythmias
        Utilization and in-hospital complications, 2000 to 2013.
        JACC Clin Electrophysiol. 2017; 3: 1240-1248
        • Ruwald A.C.
        • Schuger C.
        • Moss A.J.
        • et al.
        Mortality reduction in relation to implantable cardioverter defibrillator programming in the Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT).
        Circ Arrhythm Electrophysiol. 2014; 7: 785-792
        • Sterns L.D.
        • Meine M.
        • Kurita T.
        • et al.
        Extended detection time to reduce shocks is safe in secondary prevention patients: the secondary prevention substudy of PainFree SST.
        Heart Rhythm. 2016; 13: 1489-1496
        • Sanders P.
        • Connolly A.T.
        • Nabutovsky Y.
        • Fischer A.
        • Saeed M.
        Increased hospitalizations and overall healthcare utilization in patients receiving implantable cardioverter-defibrillator shocks compared with antitachycardia pacing.
        JACC Clin Electrophysiol. 2018; 4: 243-253
        • Kloppe A.
        • Proclemer A.
        • Arenal A.
        • et al.
        Efficacy of long detection interval implantable cardioverter-defibrillator settings in secondary prevention population: data from the Avoid Delivering Therapies for Nonsustained Arrhythmias in ICD Patients III (ADVANCE III) trial.
        Circulation. 2014; 130: 308-314
        • Mastenbroek M.H.
        • Pedersen S.S.
        • van der Tweel I.
        • Doevendans P.A.
        • Meine M.
        Results of ENHANCED implantable cardioverter defibrillator programming to reduce therapies and improve quality of life (from the ENHANCED-ICD Study).
        Am J Cardiol. 2016; 117: 596-604
        • Saeed M.
        • Neason C.G.
        • Razavi M.
        • et al.
        Programming antitachycardia pacing for primary prevention in patients with implantable cardioverter defibrillators: results from the PROVE trial.
        J Cardiovasc Electrophysiol. 2010; 21: 1349-1354
        • Wathen M.S.
        • DeGroot P.J.
        • Sweeney M.O.
        • et al.
        Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators: pacing fast ventricular tachycardia reduces shock therapies (PainFREE Rx II) trial results.
        Circulation. 2004; 110: 2591-2596
        • Santini M.
        • Lunati M.
        • Defaye P.
        • et al.
        Prospective multicenter randomized trial of fast ventricular tachycardia termination by prolonged versus conventional anti-tachyarrhythmia burst pacing in implantable cardioverter-defibrillator patients-Atp DeliVery for pAiNless ICD thErapy (ADVANCE-D) trial results.
        J Interv Card Electrophysiol. 2010; 27: 127-135
        • Gao D.
        • Van Herendael H.
        • Alshengeiti L.
        • et al.
        Mexiletine as an adjunctive therapy to amiodarone reduces the frequency of ventricular tachyarrhythmia events in patients with an implantable defibrillator.
        J Cardiovasc Pharmacol. 2013; 62: 199-204
        • Hoffmann A.
        • Follath F.
        • Burckhardt D.
        Safe treatment of resistant ventricular arrhythmias with a combination of amiodarone and quinidine or mexiletine.
        Lancet. 1983; 1: 704-705
        • Deyell M.W.
        • Steinberg C.
        • Doucette S.
        • et al.
        Mexiletine or catheter ablation after amiodarone failure in the VANISH trial.
        J Cardiovasc Electrophysiol. 2018; 29: 603-608
      2. International mexiletine and placebo antiarrhythmic coronary trial: I. Report on arrhythmia and other findings. Impact Research Group.
        J Am Coll Cardiol. 1984; 4: 1148-1163
        • Pinter A.
        • Akhtari S.
        • O’Connell T.
        • et al.
        Efficacy and safety of dofetilide in the treatment of frequent ventricular tachyarrhythmias after amiodarone intolerance or failure.
        J Am Coll Cardiol. 2011; 57: 380-381
        • Baquero G.A.
        • Banchs J.E.
        • Depalma S.
        • et al.
        Dofetilide reduces the frequency of ventricular arrhythmias and implantable cardioverter defibrillator therapies.
        J Cardiovasc Electrophysiol. 2012; 23: 296-301
        • Boriani G.
        • Lubinski A.
        • Capucci A.
        • et al.
        A multicentre, double-blind randomized crossover comparative study on the efficacy and safety of dofetilide vs sotalol in patients with inducible sustained ventricular tachycardia and ischaemic heart disease.
        Eur Heart J. 2001; 22: 2180-2191
        • Echt D.S.
        • Liebson P.R.
        • Mitchell L.B.
        • et al.
        Mortality and morbidity in patients receiving encainide, flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial.
        N Engl J Med. 1991; 324: 781-788
        • Ermakov S.
        • Hoffmayer K.S.
        • Gerstenfeld E.P.
        • Scheinman M.M.
        Combination drug therapy for patients with intractable ventricular tachycardia associated with right ventricular cardiomyopathy.
        Pacing Clin Electrophysiol. 2014; 37: 90-94
        • Bouvier F.
        • Maupain C.
        • Roche N.C.
        • et al.
        Effectiveness and safety of flecainide in arrhythmogenic right ventricular cardiomyopathy. Archives of Cardiovascular Diseases.
        Supplements. 2018; 10: 98-99
        • Koruth J.S.
        • Dukkipati S.
        • Miller M.A.
        • et al.
        Bipolar irrigated radiofrequency ablation: a therapeutic option for refractory intramural atrial and ventricular tachycardia circuits.
        Heart Rhythm. 2012; 9: 1932-1941
        • Robinson C.G.
        • Samson P.P.
        • Moore K.M.S.
        • et al.
        Phase I/II trial of electrophysiology-guided noninvasive cardiac radioablation for ventricular tachycardia.
        Circulation. 2019; 139: 313-321
        • Sacher F.
        • Sobieszczyk P.
        • Tedrow U.
        • et al.
        Transcoronary ethanol ventricular tachycardia ablation in the modern electrophysiology era.
        Heart Rhythm. 2008; 5: 62-68
        • Sapp J.L.
        • Beeckler C.
        • Pike R.
        • et al.
        Initial human feasibility of infusion needle catheter ablation for refractory ventricular tachycardia.
        Circulation. 2013; 128: 2289-2295
        • Vaseghi M.
        • Barwad P.
        • Malavassi Corrales F.J.
        • et al.
        Cardiac sympathetic denervation for refractory ventricular arrhythmias.
        J Am Coll Cardiol. 2017; 69: 3070-3080
        • Dunbar S.B.
        • Dougherty C.M.
        • Sears S.F.
        • et al.
        Educational and psychological interventions to improve outcomes for recipients of implantable cardioverter defibrillators and their families: a scientific statement from the American Heart Association.
        Circulation. 2012; 126: 2146-2172
        • Pedersen S.S.
        • van den Broek K.C.
        • Erdman R.A.
        • Jordaens L.
        • Theuns D.A.
        Pre-implantation implantable cardioverter defibrillator concerns and type D personality increase the risk of mortality in patients with an implantable cardioverter defibrillator.
        Europace. 2010; 12: 1446-1452
        • Perini A.P.
        • Kutyifa V.
        • Veazie P.
        • et al.
        Effects of implantable cardioverter/defibrillator shock and antitachycardia pacing on anxiety and quality of life: a MADIT-RIT substudy.
        Am Heart J. 2017; 189: 75-84
        • Thylen I.
        • Moser D.K.
        • Stromberg A.
        • Dekker R.A.
        • Chung M.L.
        Concerns about implantable cardioverter-defibrillator shocks mediate the relationship between actual shocks and psychological distress.
        Europace. 2016; 18: 828-835
        • Kelley A.S.
        • Reid M.C.
        • Miller D.H.
        • Fins J.J.
        • Lachs M.S.
        Implantable cardioverter-defibrillator deactivation at the end of life: a physician survey.
        Am Heart J. 2009; 157 (702-8.e701)
        • Kirkpatrick J.N.
        • Gottlieb M.
        • Sehgal P.
        • Patel R.
        • Verdino R.J.
        Deactivation of implantable cardioverter defibrillators in terminal illness and end of life care.
        Am J Cardiol. 2012; 109: 91-94
        • McEvedy S.M.
        • Cameron J.
        • Lugg E.
        • et al.
        Implantable cardioverter defibrillator knowledge and end-of-life device deactivation: a cross-sectional survey.
        Palliat Med. 2018; 32: 156-163
        • Lampert R.
        Implantable cardioverter-defibrillator shocks in dying patients: disturbing data from beyond the grave.
        Circulation. 2014; 129: 414-416