Survival Benefit of Implantable Cardioverter Defibrillators in Patients With Catecholaminergic Polymorphic Ventricular Tachycardia

Introduction: The effectiveness of implantable cardioverter-defibrillators (ICDs) in reducing mortality in patients with Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is debated.Hypothesis. The ICD confers survival benefit in patients with CPVT. Methods: We included n=238 genotype-proven CPVT patients, of whom 91 (38%) had an ICD implanted. All patients were treated with beta-blocker (BB) monotherapy. Survival probability at the occurrence of a first Life-threatening Arrhythmic Event (LAE, defined as: sudden cardiac death, aborted cardiac arrest or hemodynamically non-tolerated ventricular tachycardia) was compared between ICD carriers and non-ICD carriers. In ICD carriers, the benefit-to-harm ratio (rate of appropriate shocks on LAE over rate of major complications) was investigated. Results: During 1,643 person-years of follow-up, 35/238 (15%) patients experienced a first LAE on BB monotherapy (annual LAE rate 2.1%, 95%CI: 1.5-3.0%). Of the 35 individuals who experienced an LAE, 23 patients had an ICD when the LAE occurred, and all survived after ICD shock. Of the remaining 12 patients who were not carriers of an ICD, 4/12 (33%) died suddenly, 2/12 (17%) survived but suffered anoxic brain injury, while 6/12 (50%) survived without consequences. The probability of dying at the occurrence of a first LAE was 25-fold higher (OR: 24.9, 95% CI: 1.2-513.0; p=0.037) in patients without an ICD, as compared to patients with an ICD. Major complications occurred in 17/91 (19%) patients with an ICD (2.6% per year, 95%CI: 1.5%-4.1%). Comparing the rate of major complication to the rate of appropriate ICD shocks on LAE (LAE rate 5.2% per year, 95%CI: 3.5-7.4%), the benefit-to-harm ratio was 2, favoring the benefit of ICD therapy. Conclusion: The ICD conferred a significant survival benefit in terms of arrhythmic mortality at the occurrence of the first LAE in BB monotherapy.