Association of diastolic blood pressure and coronary artery calcium in South Asian American adults

OBJECTIVE: Diastolic blood pressure (DBP) is associated with atherosclerosis and cardiovascular disease, independent of systolic blood pressure (SBP). However, prior evaluation of the association of DBP with coronary artery calcium (CAC) has not included South Asian adults, a population that is at excess risk of atherosclerotic cardiovascular disease. METHODS: In the Mediators of Atherosclerosis in South Asians Living in America (MASALA) Study, we evaluated the association of sex-specific DBP tertiles and CAC score > = 100 with robust Poisson regression adjusted for age, sex, SBP, BP medication use, and other cardiovascular risk factors. We examined these associations stratified by antihypertensive medication use, and secondarily the association of baseline DBP tertile with incident CAC over median 4.7 years of follow-up. RESULTS: Among 1155 participants (48% women, mean age 57 years), mean (standard deviation) DBP was 74 (10) mmHg, 33% were on antihypertensive medications, and 22% had CAC > = 100. Relative to DBP in tertile 1, DBP in tertiles 2 and 3 was associated with a significantly higher prevalence of CAC > = 100 [adjusted prevalence ratio 1.30 [95% confidence interval (CI) 1.03-1.65] and 1.47 (1.12-1.93), respectively]. These significant associations were primarily observed in participants who were not on antihypertensive medications. Baseline DBP tertile was not associated with incident CAC. CONCLUSION: Among South Asian adults in MASALA, DBP in the second or third tertiles vs. tertile 1 were associated with a higher prevalence of CAC > = 100 after adjustment for covariates, including SBP. DBP may be an important clinical ASCVD risk factor among South Asian adults.