Subcutaneous versus transvenous implantable defibrillator in patients with hypertrophic cardiomyopathy

BACKGROUND Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiomyopathy. The implantable cardioverter-defibrillator (ICD) is important for prevention of sud-den cardiac death (SCD) in patients at high risk. In recent years, the subcutaneous implantable cardioverter-defibrillator (S-ICD) has emerged as a viable alternative to the transvenous implantable cardioverter-defibrillator (TV-ICD). The S-ICD does not require intra-vascular access; however, it cannot provide antitachycardia pacing (ATP) therapy. OBJECTIVE The purpose of this study was to assess the real-world incidence of ICD therapy in patients with HCM implanted with TV-ICD vs S-ICD. METHODS We compared the incidence of ATP and shock therapies among all HCM patients with S-ICD and TV-ICD enrolled in the Bos-ton Scientific ALTITUDE database. Cumulative Kaplan-Meier inci-dence was used to compare therapy-free survival, and Cox proportional hazard ratios were calculated. We performed unmatched as well as propensity match analyses. RESULTS We included 2047 patients with TV-ICD and 626 patients with S-ICD, followed for an average of 1650.5 +/- 1038.5 days and 933.4 +/- 550.6 days, respectively. Patients with HCM and TV-ICD had a significantly higher rate of device therapy compared to those with S-ICD (32.7 vs 14.5 therapies per 100 patient-years, respec-tively; P ,.001), driven by a high incidence of ATP therapy in the TV-ICD group, which accounted for .67% of therapies delivered. Shock incidence was similar between groups, both in the general and the matched cohorts. CONCLUSION Patients with HCM and S-ICD had a significantly lower therapy rate than patients with TV-ICD without difference in shock therapy, suggesting potentially unnecessary ATP therapy. Empirical ATP programming in patients with HCM may be unbeneficial.

Automated summary

This study aimed to assess the incidence of ICD therapy in patients with HCM implanted with TV-ICD vs S-ICD in real-world settings.