Comparing coronary artery cross-sectional area among asymptomatic South Asian, White, and Black participants: the MASALA and CARDIA studies

BACKGROUND

South Asian individuals have high risk of atherosclerotic cardiovascular disease (ASCVD). Some investigators suggest smaller coronary artery size may be partially responsible.

METHODS

We compared the left anterior descending (LAD) artery cross-sectional area (CSA) (lumen and arterial wall) among South Asians in the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study with White and Black participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study, adjusting for BMI, height, and other ASCVD risk factors. We used thin-slice non-contrast cardiac computed tomography to measure LAD CSA. We used linear regression models to determine whether race/ethnicity was associated with LAD CSA after adjusting for demographic factors, BMI, height, coronary artery calcium (CAC), and traditional cardiovascular risk factors.

RESULTS

Our sample included 3,353 participants: 513 self-identified as South Asian (44.4% women), 1286 as Black (59.6% women), and 1554 as White (53.5% women). After adjusting for age, BMI, height, there was no difference in LAD CSA between South Asian men and women compared to White men and women, respectively. After full adjustment for CVD risk factors, LAD CSA values were: South Asian women (19.9 mm2, 95% CI [18.8 - 20.9]) and men (22.3 mm2, 95% CI [21.4 - 23.2]; White women (20.0 mm2, 95% CI [19.4-20.5]) and men (23.6 mm2, 95% CI [23.0-24.2]); and Black women (21.6 mm2, 95% CI [21.0 - 22.2]) and men (26.0 mm2, 95% CI [25.3 - 26.7]). Height, BMI, hypertension, CAC, and age were positively associated with LAD CSA; current and former cigarette use were inversely associated.

CONCLUSIONS

South Asian men and women have similar LAD CSA to White men and women, and smaller LAD CSA compared to Black men and women, respectively, after accounting for differences in body size. Future studies should determine whether LAD CSA is associated with future ASCVD events.

Isolated HbA1c identifies a different subgroup of individuals with type 2 diabetes compared to fasting or post-challenge glucose in Asian Indians: The CARRS and MASALA studies

AIMS

Guidelines recommend hemoglobin A1c (HbA1c) as a diagnostic test for type 2 diabetes, but its accuracy may differ in certain ethnic groups.

METHODS

The prevalence of type 2 diabetes by HbA1c, fasting glucose, and 2 h glucose was compared in 3016 participants from Chennai and Delhi, India from the CARRS-2 Study to 757 Indians in the U.S. from the MASALA Study. Type 2 diabetes was defined as fasting glucose ≥ 7.0 mmol/L, 2-h glucose ≥ 11.1 mmol/L, or HbA1c ≥ 6.5%. Isolated HbA1c diabetes was defined as HbA1c ≥ 6.5% with fasting glucose < 7.0 mmol/L and 2 h glucose < 11.1 mmol/L.

RESULTS

The age, sex, and BMI adjusted prevalence of diabetes by isolated HbA1c was 2.9% (95% CI: 2.2-4.0), 3.1% (95% CI: 2.3-4.1), and 0.8% (95% CI: 0.4-1.8) in CARRS-Chennai, CARRS-Delhi, and MASALA, respectively. The proportion of diabetes diagnosed by isolated HbA1c was 19.4%, 26.8%, and 10.8% in CARRS-Chennai, CARRS-Delhi, and MASALA respectively. In CARRS-2, individuals with type 2 diabetes by isolated HbA1c milder cardio-metabolic risk than those diagnosed by fasting or 2-h measures.

CONCLUSIONS

In Asian Indians, the use of HbA1c for type 2 diabetes diagnosis could result in a higher prevalence. HbA1c may identify a subset of individuals with milder glucose intolerance.

Acculturation and Subclinical Atherosclerosis among U.S. South Asians: Findings from the MASALA study

OBJECTIVE

Longer duration of residence among immigrants to the United States, a proxy measure of acculturation, has been associated with higher subclinical atherosclerosis. South Asian immigrants are the second fastest growing immigrant group in the U.S. but little is known about the effects of acculturation with atherosclerosis in this high cardiovascular risk population.

METHODS

We conducted a cross-sectional analysis using data from a community-based cohort called the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study. Participants (n=900) were between ages of 40-84 years and had no existing cardiovascular disease. We developed a multi-dimensional measure of acculturation in South Asians, called traditional cultural beliefs, and measured other proxy measures of acculturation to determine whether they were associated with higher levels of subclinical atherosclerosis after controlling for socioeconomic, behavior/lifestyle, and cardiovascular risk factors.

RESULTS

Mean duration of residence in the U.S. was 27±11 years and tertiles of strength of traditional cultural beliefs were examined. Longer duration of U.S. residence was associated with higher levels of coronary artery calcium even after adjustment for covariates and lifestyle mediators. The novel measure of strength of traditional cultural beliefs was associated with lower common carotid intima media thickness among those with moderate traditional beliefs only.

CONCLUSIONS

These findings support the need for better conceptualization and measurement of how migration influences cultural beliefs and practices, and their subsequent influence on health behaviors and cardiovascular disease risk.