Beyond the “Benign” Label: Toward Phenotype-Specific Risk Stratification in Apical Hypertrophic Cardiomyopathy

Abstract

Apical hypertrophic cardiomyopathy (HCM) was first described nearly 5 decades ago by Yamaguchi and colleagues 1) in a Japanese cohort, characterized by giant T-wave inversion and the now-iconic "ace-of-spades" left ventricular morphology, and reported at the time with strikingly low mortality.In the decades since, apical HCM has carried the reputation of a comparatively benign subgroup of HCM to septal-dominant disease.Eriksson and colleagues, 2) writing in a Toronto cohort, documented meaningful cardiovascular morbidity even as annual mortality remained low.This strengthened the signal that apical HCM, while less lethal on average, can and does cause sudden cardiac death.2)3) The question facing the field is therefore no longer whether apical HCM is benign, but how to identify the patients in whom it is dangerous.Park and colleagues' multicenter Korean study, 4) reported in this issue of the Korean Circulation Journal, makes a meaningful contribution to that question.The authors assembled 96 HCM patients who underwent implantable cardioverter-defibrillator (ICD) implantation across three tertiary centers and identified 15 with apical HCM.Of those 15, 7 (46.7%)had been implanted after aborted cardiac arrest or documented ventricular fibrillation (VF).All 7 patients harbored at least one established sudden cardiac death risk marker prior to their index event under either the 2024 American Heart Association (AHA)/American College of Cardiology (ACC) 5) or 2023 European Society of Cardiology 6) framework.Over a mean follow-up of 6 years, neither total nor appropriate ICD therapy rates differed significantly between apical and non-apical HCM patients.The authors conclude that apical HCM is not entirely benign, and that risk-guided implantation is warranted.The cohort is small, and the comparisons are underpowered, but we believed that the qualitative pattern that emerges is more useful than the numbers.The most informative finding in this study may be which conventional risk markers were absent in the seven patients who experienced aborted cardiac arrest or documented VF.None had apical aneurysm, systolic dysfunction, family history of sudden cardiac death, or massive left ventricular hypertrophy.Instead, the observed markers were late gadolinium enhancement on cardiac magnetic resonance, unexplained syncope, non-sustained ventricular tachycardia, and left atrial enlargement-variables that are either absent from,