Heterogeneity and Detection Rate of Hypertrophic Cardiomyopathy Phenotype in China: A Multicenter Echocardiography Study

Background: Contemporary data on the clinical detection rate and profile of phenotypical hypertrophic cardiomyopathy (HCM) in major Chinese healthcare settings are limited. This multicenter study aimed to determine the detection rate and echocardiographic features of the HCM phenotype in a large Chinese cohort. Methods: This cross-sectional study analyzed echocardiography databases from nine medical centers across China, including adult patients examined during 2023. HCM phenotype was defined as end-diastolic wall thickness ≥15 mm in the left ventricle. Patients with moderate to severe aortic stenosis were excluded. Subcategories included phenotypes of obstructive HCM and apical hypertrophy. Results: Among 655,383 examinations, 2610 patients met the criteria of the HCM phenotype, yielding a detection rate of 0.40% (≈1 in 250). The mean age was 60.2 years with male predominance (70.3%). Asymmetric septal hypertrophy was present in 53.3% of patients. The most commonly involved site with maximal wall thickness was the interventricular septum (57.6%), followed by the apex (20.9%) and the basal septum (17.7%). The overall intra-left ventricular obstruction rate was 16.2%; left ventricular outflow tract obstruction (LVOTO) accounted for 12.1%. LVOTO patients had greater septal thickness, smaller left ventricular diastolic dimensions, and more mitral regurgitation. Female sex was associated with a significantly higher LVOTO rate than males (18.2% vs. 9.6%, p < 0.001). Pure apical hypertrophy was identified in 4.5% of patients, with an increasing detection rate in older age groups. Conclusions: This large-scale, multicenter study confirms a high clinical detection rate for the HCM phenotype (≈1 in 250) in major Chinese centers. Substantial phenotypic heterogeneity across age and sex, coupled with the identification of key factors associated with LVOTO, highlights the need for sex- and age-specific diagnostic strategies and therapeutic planning in clinical practice.