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 a median 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.