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Canadian Journal of Cardiology

The Optimal Timing of Primary Prevention Implantable Cardioverter-Defibrillator Referral in the Rapidly Changing Medical Landscape

Published:February 03, 2021DOI:https://doi.org/10.1016/j.cjca.2021.01.024

      Abstract

      The use of implantable cardioverter-defibrillators (ICDs) significantly reduces the risk of mortality in patients with heart failure with reduced ejection fraction (HFrEF). Current guidelines, which are based on seminal clinical trials published nearly 2 decades ago, recommend that patients be on optimal medical therapy for HF for a minimum of 3 months before referral for prophylactic ICD. This waiting period allows for left ventricular reverse remodelling and improvement in HF symptoms, which may render primary prevention ICD implantation unnecessary. However, medical therapy for HFrEF has significantly evolved since the publication of these landmark trials. Given the plethora of medical therapy options now available for HFrEF, it is appropriate to reassess the duration of this waiting period. In the present review, we examine the landmark randomised trials in primary prevention of sudden cardiac death in patients with HFrEF, summarise the novel medical therapies (sacubitril-valsartan, sodium-glucose cotransporter 2 inhibitors, ivabradine, vericiguat, and omecamtiv mecarbil) that have emerged since the publication of those trials, discuss the optimal timing of ICD referral, and review subtypes of nonischemic cardiomyopathy where timing of ICD insertion is guided by alternative criteria. With the steps now needed to optimise medical therapy for HFrEF, in terms of both classes of drugs and doses of each agent, it can easily take up to 6 months to achieve optimisation. Following that, waiting periods of 3 months for ischemic cardiomyopathy and 6 months for nonischemic cardiomyopathy may be required to allow adequate reverse remodelling before reevaluating for ICD implantation.

      Résumé

      Le recours à un défibrillateur cardioverteur implantable (DCI) réduit de manière significative le risque de mortalité chez les patients présentant une insuffisance cardiaque avec fraction d’éjection réduite (ICFER). Les lignes directrices actuelles, qui sont fondées sur les résultats d’essais cliniques fondamentaux publiés il y a près de 20 ans, recommandent de soumettre les patients à un traitement médical optimal contre l’insuffisance cardiaque pendant au moins trois mois avant de les orienter vers un spécialiste pour la pose d’un DCI prophylactique. Cette période d’attente permet le remodelage inverse du ventricule gauche et donne le temps aux symptômes d’insuffisance cardiaque de s’atténuer, ce qui pourrait rendre inutile la pose d’un DCI en prévention primaire. Les traitements médicaux de l’ICFER ont toutefois beaucoup évolué depuis la publication de ces essais phares. Compte tenu des très nombreuses options thérapeutiques maintenant offertes pour le traitement de l’ICFER, il convient de réévaluer la durée de cette période d’attente. Nous examinons ici les essais phares avec répartition aléatoire sur la prévention primaire de la mort cardiaque subite chez les patients atteints d’ICFER; nous présentons aussi un résumé des nouveaux traitements médicaux (association sacubitril-valsartan, inhibiteurs du co-transporteur sodium-glucose de type 2 [SGLT2], ivabradine, vériciguat et omécamtiv mécarbil) commercialisés depuis la publication de ces essais, traitons du moment optimal pour l’orientation aux fins de pose d’un DCI et passons en revue les sous-types de cardiomyopathie non ischémique pour lesquels le moment de la pose d’un DCI dépend d’autres critères. En raison des étapes à franchir aujourd’hui pour optimiser le traitement médical de l’ICFER, tant en ce qui concerne les classes de médicaments que les doses de chacun des agents, cette optimisation peut facilement prendre jusqu’à six mois. Par la suite, il peut être nécessaire d’attendre trois mois (dans le cas d’une cardiomyopathie ischémique) ou six mois (dans le cas d’une cardiomyopathie non ischémique) avant de réévaluer la nécessité de la pose d’un DCI, afin de permettre un remodelage inverse adéquat.
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