LEFT VENTRICULAR MASS AND URINARY METABOLOMICS IN YOUNG BLACK AND WHITE ADULTS: THE AFRICAN-PREDICT STUDY

Objective: Increased left ventricular mass is an independent predictor for cardiovascular events, and shown to be higher in black than white populations. To gain a better understanding of early factors contributing to increased left ventricular mass in young black adults, we investigated metabolomic profiles and identified metabolites associated with left ventricular mass index in healthy black and white adults aged 20–30 years. Design and method: We included normotensive black (N = 80) and white (N = 80) participants from the African-PREDICT study, with data on urinary metabolomics and echocardiography. Urinary metabolites were measured using nuclear magnetic resonance spectroscopy, liquid chromatography tandem mass spectrometry and gas chromatography time-of-flight mass spectrometry. Univariate statistical analyses, including independent t-test (adjusted for multiple comparisons), effect size (d > = 0.3) and single regression analyses were used to identify metabolites. Results: When comparing the black and white groups, the black group had lower body weight (p < 0.001) and protein intake (p = 0.014). Central systolic blood pressure was higher in the black group compared to the white group (p > 0.005), whereas left ventricular mass index was similar between the groups (p = 0.97). Three from a total of 192 metabolites were identified to be more abundant (p < 0.046) and inversely associated with left ventricular mass index in the black group only: hydroxyproline (beta = –0.24; p = 0.020), glycine (beta = –0.23; p = 0.025) and trimethylamine (beta = –0.22; p = 0.026). Conclusions: Higher urinary levels of hydroxyproline, glycine and trimethylamine were inversely associated with left ventricular mass index in the black adults only. Hydroxyproline and glycine are important in maintaining healthy collagen turnover and stability in the heart. Our results may reflect an increase in collagen biosynthesis and collagen deposition in the left ventricle due to higher central systolic blood pressure in the black population.