West African Genetic Ancestry and Blood Pressure Response in the SPRINT Trial

By Ambarish Pandey, M.D., Assistant Professor of Internal Medicine, and Shreya Rao, M.D., Cardiology Fellow

At this year’s AHA Scientific Sessions, we presented findings from our study evaluating the association of genetic West African ancestry with blood pressure response and cardiovascular outcomes among Black participants in the Systolic Blood Pressure Reduction Intervention Trial (SPRINT). Although hypertension is highly prevalent among Black individuals in the United States, and the risks of cardiovascular and kidney outcomes are disproportionately greater in Black adults, the contribution of genetic risk to blood pressure control and downstream risk has not been established. Prior studies have attributed differences in blood pressure by race to a combination of genetic, environmental, societal, and behavioral factors but have stopped short of estimating the relative contribution of each due to challenges in measuring the influence of structural racism and other social inequities. SPRINT, a clinical trial that randomized participants to intensive (< 120 mm Hg) or standard (< 140 mm Hg) systolic blood pressure control, presented a unique opportunity to study blood pressure response by genetic ancestry because all participants in the trial were afforded equal access to providers and treatments for the duration of the study. The design of the trial thus allowed us to study race-related disparities in a setting where access to care was comparable among all participants.

In SPRINT, West African ancestry was estimated in 2,500 Black participants. We categorized participants into three groups, from lowest to highest proportion of West African ancestry, and evaluated the trajectories of blood pressure by ancestry group over the study period (median follow-up of 3.2 ± 0.9 years). We also assessed the relationship between West African ancestry proportion and baseline prevalence of left ventricular hypertrophy (by Cornell Voltage), the number of anti-hypertensive drugs required to achieve blood pressure control, cardiovascular outcomes (such as nonfatal myocardial infarction, stroke, acute heart failure, or cardiovascular death), and kidney function parameters (including serum creatinine, blood urea nitrogen, and urine/albumin creatinine). We found that West African ancestry was not significantly associated with blood pressure control or kidney function changes over time and was associated with a slightly lower risk of cardiovascular events. Although West African ancestry was associated with an increased baseline prevalence of LVH, it was not associated with trajectories in LV mass or the number of medications required to achieve blood pressure control. Together, the results suggest that the contribution of global genetic West African ancestry to population-level disparities in blood pressure control and hypertension-related adverse events is likely small and highlights the importance of societal factors in driving observed disparities.