Ethnicity Differences in Geometric Remodeling and Myocardial Composition in Hypertension unveiled by Cardiovascular Magnetic Resonance.

Abstract

Hypertensive patients of African-ancestry (Afr-a) have higher incidences of heart failure and worse clinical outcomes than hypertensive patients of European-ancestry (Eu-a), yet the underlying mechanisms remain misunderstood. This study investigated right (RV) and left (LV) ventricular remodeling alongside myocardial tissue derangements between Afr-a and Eu-a hypertensives. Sixty-three Afr-a and forty-seven Eu-a hypertensives underwent multi-parametric cardiovascular-magnetic-resonance. Biventricular volumes, mass, function, mass/end-diastolic volume (M/V) ratios, T2- and pre/post-contrast T1-relaxation-times, synthetic-extracellular-volume (s-ECV) and myocardial fibrosis (MF) were measured. Three-dimensional shape modeling was implemented to delineate ventricular geometry.LV and RV-mass (indexed to body-surface-area) and M/V ratios were significantly greater in Afr-a than Eu-a hypertensives (67.1±21.7 vs. 58.3±16.7g/m2, 12.6±3.48 vs. 10.7±2.71g/m2, 0.79±0.21 vs. 0.70±0.14g/ml, 0.16±0.04 vs. 0.13±0.03g/ml, respectively; P<0.03) mirroring LV remodeling. Afr-a patients showed greater basal-interventricular-septum thickness than Eu-a patients, which may influence LV hypertrophy and RV cavity changes. This biventricular remodeling was associated with prolonged T2-relaxation-time (47.0±2.2 vs. 45.7±2.2ms, P=0.005) and higher prevalence (23% vs. 4%, P=0.001) and extent of MF (2.3[0.6-14.3] vs. 1.6[0.9-2.5] % of LV-mass, P=0.008) in Afr-a patients. Multivariable linear regression showed modifiable cardiovascular risk-factors and greater end-diastolic volume were independently associated with greater LV or RV-mass. Furthermore, ethnicity was independently associated with greater RV-mass, supporting our hypothesis of ethnic-specific hypertensive remodeling. Afr-a hypertensives had distinctive biventricular remodeling, including increased RV-mass and septal thickening, and subtle myocardial tissue abnormalities compared to Eu-a hypertensives. From this study, modifiable cardiovascular risk-factors, and ventricular geometry, but not ethnicity, were independently associated with higher LV mass.