Subcutaneous implantable cardioverter-defibrillator in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia: A transatlantic experience

Background-Despite growing use of the subcutaneous implantable cardioverter-defibrillator (S-ICD), its clinical role in arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) patients remains undefined. We aim to elucidate the cardiac phenotype, implant characteristics, and long-term efficacy regarding appropriate therapy and complications in ARVC/D patients with an S-ICD implant. Methods and Results-A transatlantic cohort of ARVC/D patients who underwent S-ICD implantation was analyzed for clinical characteristics, S-ICD therapy, and long-term outcome including device-related complications. The cohort included 29 patients (52% male, 76% probands, 59% with ARVC/D-associated mutation, 59% primary prevention [no prior sustained ventricular arrhythmias], and 45% first-generation S-ICD devices). At implant, all inducible patients (27/29) had conversion of induced ventricular fibrillation. Two patients (7%) had superficial infections of the incision site that were treated conservatively. Over amedian follow-up of 3.16 years (interquartile range: 2.21-4.51 years), all episodes (6 patients, 4% per year) of sustained ventricular arrhythmias were appropriately detected and treated. Six patients (21%) experienced 39 inappropriate shocks, with 3 requiring device explantation. Oversensing of noncardiac signal (n=4; especially myopotentials) and cardiac signal (n=4) was the most frequent etiology. No lead or device dislodgement, infection, skin erosion, or explantation related to need for antitachycardia pacing was noted. Conclusions-S-ICD can effectively treat both induced and spontaneous ventricular arrhythmias in patients with ARVC/D. The rate of inappropriate shocks, although considerable, is comparable to that in ARVC/D patients treated with transvenous ICDs. When they occurred, inappropriate shocks were primarily due to cardiac and, uniquely, noncardiac oversensing. We suggest potential strategies for minimizing inappropriate therapy.