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Canadian Journal of Cardiology

SURVIVAL, VENTRICULAR ARRHYTHMIA, AND IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR USEFULNESS IN A COHORT OF PATIENTS WITH TOXIC DILATED CARDIOMYOPATHY

      Background

      Toxic dilated cardiomyopathy (T-DCM) is now recognized as a potential cause of severe left ventricular dysfunction. Abuse of substances such as amphetamines, methamphetamines, cocaine, anabolic steroids, and energy drinks can cause various cardiovascular effects, repolarization perturbation, ventricular arrhythmias, and sudden cardiac death due to many mechanisms. The burden of ventricular arrhythmias (VA) and the role of a prophylactic implantable cardioverter-defibrillator (ICD) are not well documented in this population. We aim to assess the value of ICD implantation in a cohort of T-DCM.

      Methods and Results

      Patients younger than 65 years old with a left ventricular ejection fraction (LVEF) < 35% followed at a tertiary center heart failure clinic between January 2003 and August 2019 were screened for inclusion. The diagnosis of T-DCM was confirmed after excluding other etiologies, and substance abuse was established according to the DSM-5 criteria. The composite primary endpoints were arrhythmic syncope, sudden cardiac death, or death of unknown cause. The secondary endpoint was the occurrence of sustained VAs and/or appropriate therapies in ICD carriers. The proportion of patients qualifying for an ICD in primary prevention at 12 months was assessed as an exploratory endpoint. Thirty-eight patients were identified, and an ICD was implanted in 19 (50%) of these patients. In the 19 other patients, no ICD was implanted for the following reasons: early LVEF recovery ≥35% during the first six months (n=13), noncompliance to treatment (n=5), and early heart transplantation (n=1). Six deaths occurred, with no significant differences between the 2 groups (ICD vs. non-ICD; p=0.14). After a mean follow-up of 33±36 months, only two VA episodes were reported in the ICD group. Three patients received inappropriate ICD therapies. One ICD implantation was complicated with cardiac tamponade. Twenty-three patients (61%) had an LVEF ≥35% at 12 months.

      Conclusion

      VAs are rare in the T-DCM population and the benefit of prophylactic ICD insertion was not seen in our small cohort. Since LVEF recovery is observed up to 12 months after the initial diagnosis, with few appropriate therapies after ICD implantation, it could be reasonable to assess the ICD indication later in the management of these patients, potentially between 6 and 12 months.
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