Utilization and Outcomes of Primary Prevention Implantable Cardioverter‐Defibrillators in Patients With Hypertrophic Cardiomyopathy

BACKGROUND: There is uncertainty about the appropriate use of primary prevention implantable cardioverter‐defibrillators (ICDs) among older patients with hypertrophic cardiomyopathy. METHODS AND RESULTS: Patients with hypertrophic cardiomyopathy who received a primary prevention ICD between 2010 and 2016 were identified using the National Cardiovascular Data Registry ICD Registry. Trends in ICD utilization and patient characteristics were assessed over time. Using linked Centers for Medicare and Medicaid Service claims data, Cox proportional hazard models assessed factors associated with mortality and postdischarge hospitalization for cardiac arrest/ventricular arrhythmia. Of 5571 patients with hypertrophic cardiomyopathy, 1511 (27.1%) were ≥65 years old. ICD utilization increased over time in all age groups. There were no changes in the prevalence of risk factors for sudden cardiac death over time. The variables most strongly associated with postdischarge mortality were older age (adjusted hazard ratio (aHR) 1.80 [95% CI, 1.47–2.21]), New York Heart Association class (III/IV versus I/II aHR 2.17 [95% CI, 1.57–2.98]), and left ventricular ejection fraction (left ventricular ejection fraction ≤35% versus >50% aHR 2.34 [95% CI, 1.58–3.48]; left ventricular ejection fraction 36%–50% versus >50% aHR 2.98 [95% CI, 2.02–4.40]), while history of nonsustained ventricular tachycardia (aHR 2.38 [95% CI, 1.62–3.51]) and New York Heart Association class (III/IV versus I/II aHR 1.84 [95% CI, 1.22–2.78]) were strongly associated with hospitalization for ventricular arrhythmia/cardiac arrest. CONCLUSIONS: Primary prevention ICD utilization in patients with hypertrophic cardiomyopathy increased over time, including among those ≥65 years old. Among older patients, the strongest risk factors for hospitalization for ventricular arrhythmia/cardiac arrest following ICD implantation were history of nonsustained ventricular tachycardia and New York Heart Association class.