Clinical Characteristics and Real-World Outcomes of Hypertrophic Cardiomyopathy Patients Undergoing ICD Implantation

Implantable cardioverter-defibrillator (ICD) therapy is essential for preventing sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). However, real-world data regarding transvenous ICD (TV-ICD) and subcutaneous ICD (S-ICD) systems in patients with HCM remain limited.We retrospectively analyzed 279 patients diagnosed with HCM at Nippon Medical School Hospital between 2003 and 2025. Among them, 75 patients who underwent ICD implantation were included. Baseline characteristics, ICD therapies, and device-related complications were compared between TV-ICD and S-ICD groups.Of the 75 patients, 63 received TV-ICDs and 12 received S-ICDs. Patients in the S-ICD group were younger and taller, with shorter follow-up duration. Established risk factors for sudden cardiac death were generally more frequent in the TV-ICD group, with significant differences in syncope and inducible ventricular fibrillation. During follow-up, there were no significant differences between groups in total ICD therapies, appropriate shocks, inappropriate shocks, or mortality. Anti-tachycardia pacing (ATP) was observed exclusively in the TV-ICD group. Device infections requiring system removal occurred only in the TV-ICD group.In this single-center observational cohort, no statistically significant differences in major clinical outcomes were observed between S-ICD and TV-ICD groups during follow-up. Given its favorable complication profile, S-ICD may represent a feasible alternative in selected younger patients with HCM.