LAUSR

Introduction: Hypertrophic cardiomyopathy (HCM) in Black populations remains underexplored even though this inherited disorder can affect more than 220,000 Blacks in the US alone. Existing data suggest that Blacks with HCM are less likely to have obstructive physiology, but uncommon phenotypes, such as mid-ventricular obstruction have not been reported. Mortality outcomes have been reported as similar between groups. Objective: To evaluate structural HCM features and outcomes in Blacks and Whites with HCM Methods: The study design was a retrospective analysis of a prospective longitudinal observational study of a referred patient population with confirmed HCM and self-identifying as Black/African American and White/Caucasian. Results: We studied 434 individuals, 57 (13.1%) were Black. Males were 52.6% of the Black cohort and 59% of the White cohort. Blacks were younger, mean (SD) 54.6 (13.4) vs 62.6 (14.8) years, p<0.001. Ejection fraction and left ventricular hypertrophy (LVH) magnitude were similar between groups but LVH distribution differed with Blacks having more sub-basal LVH, which includes apical, apical-mid and mid LVH, 22 (38.6%) vs 56 (14.9%), p<0.001, and diffuse LVH, 6 (10.5%) vs 15 (4.0%), p=0.017, than Whites. Blacks also had more mid-ventricular obstruction, 7 (12.3%) vs 21 (5.5%), p=0.025. Of those who had a cardiac MRI, Blacks had more significant fibrosis (≥15% of LV mass), 10 (30.3%) vs 20 (9.5%), p<0.001. Mortality was low overall and both groups had similar proportion of ICD insertion for primary prevention of sudden death. However, Blacks had more appropriate ICD interventions, 5 (38.5%) vs 5 (6.8%), p=0.001. Conclusions: Blacks with HCM have more sub-basal LVH and mid-ventricular obstruction than Whites with HCM, phenotypes associated with worse disease progression. They are more likely to have significant myocardial fibrosis which has a pro-arrhythmic effect. They also had more aborted sudden death events. Precise evaluation of HCM structural and physiologic characteristics can improve targeted treatment and outcomes in this population.