170 Ethnic differences in phenotypic expression of hypertrophic cardiomyopathy

Abstract

Purpose Hypertrophic Cardiomyopathy is a heterogeneous condition with variable phenotypic expression. Current studies are based on predominantly Caucasian cohorts (white patients; WP), therefore the phenotypic manifestations of HCM in individuals of African/Afro-Caribbean origin (black patients; BP) are not fully realised. Data in athletes and hypertensive patients indicate that black ethnicity is associated with a greater prevalence of repolarisation abnormalities on the ECG as well as a greater magnitude of left ventricular hypertrophy (LVH), highlighting the importance of defining the HCM phenotype in this ethnic group. Methods Between 2001 and 2010, 155 consecutive patients with HCM (52 BP, 103 WP) were assessed in 3 specialist cardiomyopathy clinics in South London. All individuals underwent comprehensive cardiac evaluation including 12-lead ECG and echocardiography. Patients subject to therapeutic interventions potentially affecting repolarisation patterns were excluded. Results Black patients revealed significantly different echocardiographic patterns of LVH, with more concentric (44.2% vs 30.1%) and apical (28.8% vs 11.7%) hypertrophy compared to WP who exhibited more asymmetric septal hypertrophy (57.3% vs 25.0%) (p=0.004). Black patients exhibited a similar magnitude of LVH compared to WP (17.3±4.9 vs 18.8±4.1 mm, p=0.069). Relating to ECG repolarisation abnormalities, BP exhibited more T wave inversions in the lateral leads (76.9% vs 60.2%, p=0.038) and deep (≥−0.2 mV) T-wave inversions (69.2% vs 51.5%, p=0.035). Black patients also tended to display more ST segment depression (50.0% vs 35.0%, p=0.071), although this was not statistically significant. In contrast, WP had significantly more pathological Q waves (23.3% vs 9.6%, p=0.039). Conclusions Ethnicity appears to exert a significant effect on ECG and echocardiographic patterns in patients with HCM. A significant proportion of black patients exhibit concentric LVH, highlighting the diagnostic challenges in distinguishing HCM from hypertensive heart disease and physiological adaptation to exercise in black individuals. The greater prevalence of deep T wave inversions and T wave inversions in the lateral leads underscores the importance of further evaluation of black individuals with such ECG repolarisation abnormalities, which may represent the initial expression of HCM.