Abstract 11447: Low Incidence of Appropriate Therapy Following Defibrillator Implantation for Primary Prevention of Sudden Cardiac Death in Hypertrophic Cardiomyopathy

Abstract

Introduction: Hypertrophic cardiomyopathy (HCM) is a leading cause of sudden cardiac death (SCD) in young adults. Implantable cardioverter defibrillators (ICD) effectively terminate ventricular tachycardia (VT) and fibrillation (VF) that cause SCD, but the reported prevalence of and patient characteristics leading to appropriate ICD therapy in HCM have been variable. Hypothesis: We hypothesized that some risk factors may be more prevalent than others in patients with HCM who receive appropriate ICD therapy and that the overall incidence of appropriate therapy may be lower than that reported previously. Methods: We retrospectively studied all patients with HCM who were treated with ICDs at our referral center from 2000-2013 to determine the rates of appropriate and inappropriate ICD therapies. Results: Of 1136 patients with HCM, we identified 135 who underwent ICD implantation (125 for primary and 10 for secondary prevention), aged 18-81 years (mean 48±17) at the time of implantation. The mean follow-up time was 5.2±4.5 years. Appropriate ICD intervention occurred in 20 of 135 patients (2.8%/year) by providing a shock or antitachycardia pacing in response to VT or VF. The annual rate of appropriate ICD therapy was 2.4%/year for primary and 7.2%/year for secondary prevention devices. Commonly used risk factors were equally prevalent among patients who received appropriate therapy and those who did not; furthermore, the likelihood of receiving appropriate therapy in the presence of each risk factor was similar (Figure). Inappropriate ICD therapy occurred in 27 patients (3.8%/year). Conclusions: ICDs provide clear benefit to patients who experience life-threatening arrhythmias, particularly those being treated for secondary prevention. However, the appropriate therapy rate for primary prevention was lower than previously reported, and no single risk factor appeared to have stronger association with appropriate ICD therapy than others.