Identifying hypertrophic cardiomyopathy (HCM) patients who warrant a primary-prevention implantable cardioverter defibrillator(ICD) is crucial. ICDs are effective in terminating life-threatening arrhythmias; however, ICDs carry risks of complications.
To assess the incidence and predictors of appropriate ICD therapies, inappropriate shocks and device-related complications in HCM patients with primary-prevention ICDs.
All HCM patients who underwent primary-prevention ICD implantation at Toronto General Hospital between 9/2000-12/2017 were identified. Therapies (shocks or anti-tachycardia pacing) for ventricular tachycardia>180bpm or ventricular fibrillation were considered appropriate.
302 patients were followed for a mean 6.1 years(1,801 patient years follow-up). 38 patients(12.6%) received at least one appropriate ICD therapy(2.3%/year); 5-year cumulative probability of receiving appropriate ICD therapy 9.6%. None of the conventional risk factors nor the European Society of Cardiology risk-score were associated with appropriate ICD therapy. On multivariable analysis, age<40 at implant and atrial fibrillation were independent predictors of appropriate ICD therapy. In a sub-group of patients who had cardiac magnetic resonance imaging prior to ICD implantation, severe late gadolinium enhancement (LGE) was the strongest predictor of appropriate ICD therapies. ICD-related complications or inappropriate shocks occurred in 28.8% of patients, with an inappropriate shock rate of 2.1%/year; 5-year cumulative probability 10.7%.
The incidence of appropriate ICD therapies in HCM patients with primary-prevention ICDs is lower than previously reported; a high proportion of patients suffer an ICD-related complication. Traditional risk factors have low predictive utility. Severe LGE, atrial fibrillation and young age are important predictors of ventricular tachyarrhythmias in HCM.

Copyright © 2020. Published by Elsevier Inc.