Distinct clinical characteristics of apical compared with non-apical hypertrophic cardiomyopathy: insights from a multicentre cohort
B K Chung, E Z Chan, H S Ling, W K Ho, M W Chan, S A Hussin, C Y Tan, K Gobal, K Raja, M H RoslanAbstract
Background
Apical hypertrophic cardiomyopathy (ApHCM) is considered a distinct morphological subtype of hypertrophic cardiomyopathy (HCM), but data comparing its clinical profile and outcomes with non-apical HCM (Non-ApHCM) remain limited, particularly from multicentre cohorts.
Methods
We conducted a retrospective, multicentre observational study across seven tertiary care centres. Adult patients diagnosed with HCM were identified and categorized into apical and non-apical subtypes based on imaging findings. Demographic characteristics, clinical presentation, comorbidities, treatment patterns, echocardiographic parameters, and clinical outcomes were collected and compared between groups. Categorical variables were analyzed using Pearson’s chi-square test, and continuous variables were compared using appropriate parametric tests.
Results
A total of 102 patients were included, of whom 20 (19.6%) had apical HCM and 82 (80.4%) had non-apical HCM. Patients with apical HCM were diagnosed at an older age (57.7 ± 15.2 vs 47.1 ± 15.7 years, p = 0.009) and had a higher prevalence of hypertension (80.0% vs 46.3%, p = 0.007). Left ventricular outflow tract obstruction (≥30 mmHg) was observed exclusively in the non-apical group (30.4% vs 0%, p = 0.028). Non-apical HCM demonstrated higher rates of syncope (14.6% vs 0%, p = 0.069), ventricular tachycardia (11.3% vs 5.3%, p = 0.436), stroke/TIA (10.0% vs 0%, p = 0.151), implantable cardioverter-defibrillator implantation (16.0% vs 0%, p = 0.077), and septal reduction therapy (14.7% vs 0%, p = 0.084), though these differences were not statistically significant. Arrhythmia burden, all-cause admissions and mortality were otherwise similar between groups.
Conclusions
Apical HCM is characterized by older age at diagnosis and a higher prevalence of hypertension. Despite morphological and hemodynamic differences, short- to intermediate-term clinical outcomes appear broadly similar between the two subtypes. These findings support the recognition of apical HCM as a distinct clinical phenotype within the HCM spectrum.