Appropriate Implantable Defibrillator Therapy in Adults With Hypertrophic Cardiomyopathy

Implantable cardioverter-defibrillators (ICDs) are effective at terminating the ventricular arrhythmias that cause sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). However, identifying patients at risk for SCD remains an ongoing challenge.

We retrospectively studied all adult patients with HCM treated with ICDs at our referral center from 2000 to 2013 to determine the risk factor profile, rates of appropriate ICD therapy, and complications associated with ICD implantation and discharge. Over a mean follow-up period of 5.2 ± 4.5 years, ICDs provided appropriate therapy to 25 of 135 patients (2.6%/year for primary prevention, 9.8%/year for secondary prevention). Established risk factors for SCD were equally prevalent among patients who received appropriate therapy and those who did not. There were similar rates of appropriate therapy for primary prevention patients with each risk factor. Patients with multiple risk factors had similar rates of appropriate therapy to patients with a single risk factor. Patients who underwent implantation at a younger age were more likely to experience appropriate therapy. Inappropriate therapy occurred in 27 of 135 patients (20%).

These data indicate that the rate of appropriate ICD therapy for primary prevention in a contemporary adult HCM population is lower than previously reported. The frequency of appropriate therapy was equally modest regardless of the nature and number of risk factors that led to ICD implantation, and patients with multiple risk factors for SCD did not have an increased rate of appropriate therapy.