Implantable Cardioverter-Defibrillator Therapy in Apical Hypertrophic Cardiomyopathy: Insights From a Multicenter Study

BACKGROUND AND OBJECTIVES: Prognosis and risk markers of sudden cardiac death (SCD) remain incompletely defined in patients with apical hypertrophic cardiomyopathy (HCM). This study evaluated established SCD risk markers and compared long-term implantable cardioverter-defibrillator (ICD) therapy outcomes between apical and non-apical HCM. METHODS: We analyzed 96 patients with HCM who underwent ICD implantation at 3 tertiary care hospitals in Korea. All SCD risk markers recommended by the 2024 American Heart Association (AHA)/American College of Cardiology (ACC) and 2023 European Society of Cardiology (ESC) guidelines were assessed in apical HCM patients who experienced aborted cardiac arrest (ACA) and/or documented ventricular fibrillation (VF). The long-term outcomes of ICD therapies between apical and non-apical HCM patients were evaluated. RESULTS: Of the 15 patients (15.6%) with apical HCM, 7 (46.7%) experienced ACA and/or documented VF. All 7 patients had at least one SCD risk marker as defined by the 2024 AHA/ACC or 2023 ESC guidelines. The most common markers were late gadolinium enhancement, unexplained syncope, non-sustained ventricular tachycardia, and left atrial enlargement. No significant differences were observed in total (33.3% [5/15] vs. 30.9% [25/81], p=1.00) or appropriate (13.3% [2/15] vs. 19.8% [16/81], p=0.73) ICD therapy events between patients with apical and non-apical HCM over a mean follow-up of 6.03±4.75 years. CONCLUSIONS: Patients with apical HCM who received ICDs for secondary prevention exhibited substantial risk markers at the index event and remained at risk for recurrent ventricular arrhythmias. These findings support risk-guided ICD implantation and careful long-term follow-up in patients with high-risk apical HCM.