Clinical Characteristics and Outcomes in Patients With Apical and Nonapical Hypertrophic Cardiomyopathy.

Background: Apical hypertrophic cardiomyopathy (ApHCM) is a variant of hypertrophic cardiomyopathy, with distinct clinical characteristics and outcomes. We aimed to clarify the natural history of patients with ApHCM and identify the risk of end-stage heart failure incidence.
Methods and Results: This retrospective study was conducted on patients with hypertrophic cardiomyopathy in China between January 2009 and February 2024. Patients were stratified into ApHCM and non-ApHCM groups. The primary outcome was a composite of major adverse cardiovascular events, including all-cause deaths, heart failure hospitalization, sudden cardiac death, and ventricular tachycardia. The secondary outcome was the incidence of end-stage heart failure, defined as left ventricular ejection fraction <50%. Kaplan-Meier and univariable and multivariable Cox proportional analyses were applied. Adjustment variables were included for important baseline characteristics, comorbidities, and medication use. Of 5653 patients enrolled with hypertrophic cardiomyopathy, 584 (10.3%) had ApHCM and 5069 (89.7%) had non-ApHCM. During the median follow-up period of 4.6 years (1.6-8.0 years), major adverse cardiovascular events occurred in 32.2% (n=1808), with a lower incidence in patients with ApHCM than non-ApHCM (20.4% versus 33.3%, P <0.001). Non-ApHCM was an independent predictor of major adverse cardiovascular events (hazard ratio [HR], 1.65 [95% CI, 1.36-1.99]; P <0.001). In the serial cohort, patients with ApHCM exhibited a lower incidence of end-stage heart failure than those with non-ApHCM (12.4% versus 2.7%, P <0.001). Non-ApHCM was associated with a higher risk of end-stage heart failure development (HR, 2.31 [95% CI, 1.28-4.15]; P <0.001). In subgroup and sensitivity analysis, the results were consistent for our main and secondary outcomes.
Conclusions: ApHCM is relatively common in hypertrophic cardiomyopathy and shows lower rates of all-cause mortality and heart failure hospitalizations than non-ApHCM.