Efficacy and Safety of the ICD in ARVC Patients

Introduction: Implantable Cardioverter Defibrillators (ICD) are used to prevent Sudden Cardiac Death (SCD) in patients with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), but data on their efficacy and safety in the long-term are scant. Methods: We reviewed our prospective registry for ARVC patients who were carriers of an ICD. Results: Eighty-one ARVC patients (55 males) received an ICD at 42±15 years: 13 (16%) patients were implanted for “secondary prevention” of SCD, after surviving an episode of ventricular fibrillation (VF) or polymorphic ventricular tachycardia (pVT); 68 (84%) patients were implanted for “primary prevention” of SCD, presenting one or more of the following putative risk factors: documentation of arrhythmic syncope (24%) or of sustained monomorphic VT (46%), familial history of SCD (40%), inducibility of VF at programmed electrical stimulation (50%), presence of a pathogenic mutation (47%). During 7±4.8 years of follow-up, 35/81 (43%) patients experienced a first episode of VF/pVT triggering an appropriate ICD shock, with an annual rate of 10% (5.9% per year in “secondary prevention” patients, 11% per year in “primary prevention” patients; p=0.24). Male gender (Hazard Ratio, HR, 3.1, 95%CI 1.27-7.51;p=0.013) and history of arrhythmic syncope (HR 3.07, 95%CI 1.51-6.23;p=0.002) predicted independently an increased risk of ICD shock on VF/pVT. Overall, 17/81 (21%) patients experienced multiple VF/pVT episodes (median 3, IQR 2-4). A total of 71 separate VF/pVT episodes were recorded, which were efficaciously interrupted by the ICD in 99% (70/71) of the cases. One patient experiencing an arrhythmic storm was not saved by the device, despite receiving several appropriate shocks. Inappropriate shocks occurred in 18/81 patients (22%) with an annual rate of 3.8%, mostly due to supraventricular tachycardia (83%). Major complications requiring the revision of the implant occurred in 5/81 (6.1%) patients, with an annual rate of 1%. Conclusions: Appropriate ICD shocks on VF/pVT occurred with an annual rate of 10% in our ARVC patients. The ICD proved to be highly effective, interrupting 99% of life-threatening arrhythmic episodes. Major complications occurred in 1% of patients per year.