Long-Term Comparison of Apical Versus Asymmetric Hypertrophic Cardiomyopathy

Abstract

Although apical hypertrophic cardiomyopathy (HCM) has been considered to be more benign than asymmetric HCM, few studies have directly compared their clinical features. We compared the electrocardiographic data and longterm outcomes between patients with apical HCM versus asymmetric HCM. This retrospective study enrolled 796 patients (243 apical HCM and 553 asymmetric HCM). We assessed long-term all-cause and cardiac mortalities using an inverse probability of treatment weighted (IPTW) method and propensity score matched (PSM) analysis. In patients with asymmetric HCM, QT prolongation, QRS widening, PR prolongation, and pathologic Q wave were significantly more frequent. The incidences of early repolarization were similar (11% in apical and 12% in asymmetric HCM, P = 0.19). The median follow-up duration was 6.5 years. There was a borderline significant difference in overall survival rates between the apical and asymmetric HCM groups (73% versus 69%, log rank P = 0.38, IPTW: P = 0.05, PSM: P = 0.05). Regarding cardiac death, asymmetric HCM was more hazardous than apical HCM (89% versus 77%, log rank P = 0.04, IPTW: P = 0.03, PSM: P = 0.03). There was no electrocardiographic predictor for the long-term outcomes, although beta-blocker use was significantly associated with lower overall death (HR = 0.58, 95% CI = 0.41-0.81) and slightly lower cardiac death (HR = 0.86, 95% CI = 0.55-1.33). The overall survival rate of apical HCM was as high as that of asymmetric HCM, but the cardiac survival rate was significantly lower in patients with asymmetric HCM. Beta-blocker use was associated with better long-term outcomes.