Abstract 8798: Ethnic Differences in the Phenotypic Expression of Hypertrophic Cardiomyopathy

Abstract

Purpose: Hypertrophic Cardiomyopathy (HCM) is a heterogeneous condition with variable phenotypic expression. Current studies are based on predominantly Caucasian cohorts (white patients; WP), and the phenotypic manifestations of HCM in individuals of African/Afro-Caribbean origin (black patients; BP) are not fully realized. 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. All underwent comprehensive evaluation including 12 lead ECG and echocardiography. Results: Black patients exhibited 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 (maximum left ventricular wall thickness 17.3±4.9 mm vs. 18.8±4.1 mm, p=0.069). Relating to ECG repolarisation abnormalities, BP exhibited significantly 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 displayed 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 the 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.