South Asians and Coronary Plaque Registry

To establish a registry of individuals who self-report as South Asian ethnicity with coronary plaque assessment to better understand plaque characteristics in this high-risk group and facilitate future studies investigating the increased coronary disease risk in this population.

South Asian individuals (SAs) are an expanding minority group in the United States (U.S.) with marked excess cardio-metabolic risk. SAs (primarily India, Pakistan, Bangladesh, Nepal, Sri Lanka) are one of the fastest-growing minority groups in the U.S., with an estimated 40% population growth from 2010-2017 (5.4 million in 2017).1-3 SAs in diaspora countries have markedly increased risk of atherosclerotic cardiovascular disease (ASCVD), particularly coronary heart disease (CHD), compared with most other races, ethnicities, and nationalities.4-5 In analysis of census-derived CVD mortality from 2003-2010 across 34 states in the U.S. with over 10 million death records,6 SAs, unlike other Asian groups, had a higher proportionate mortality ratio for ASCVD compared to non-Hispanic White Americans. Similarly, recent data from California revealed an adjusted 2-fold increased incidence of CHD in SA vs. White individuals.7 Moreover, SAs often present with premature ASCVD (7-10 years younger than White persons)8, 9 and more diffuse ASCVD (multiple vascular territories), a consistent finding across diaspora countries.10 The global cardiovascular community has officially recognized SA ethnicity as a "risk-enhancing factor" in the 2018 ACC/AHA Prevention Guidelines11 as well as by incorporating various SA countries of origin in the QRISK2/3 risk calculator used in the U.K.12 Reducing morbidity and mortality from ASCVD in SAs is a clear priority and unmet need.

Prior studies of coronary calcium have not distinguished differences in calcification of coronary artery plaques in this high-risk group, perhaps because arterial plaque calcification is a late-stage process related to aging. Given the premature presentation of coronary disease in SAs and the well-established observation in predominantly White individuals that non-calcified plaque features lead to plaque rupture and myocardial infarction. Therefore, characterizing non-calcified plaque features in SAs may lead to a better understanding of the increased risk in this population and more tailored preventive strategies.

Coronary CT angiogram (CCTA) provide detail information about plaque characteristics and fully assesses both calcified and non-calcified plaque features in the coronary arteries. This information cannot be obtained by any other imaging test and certainly no blood test. CCTA is considered a Class I indication for assessment of chest pain based on its prognostic potential and is a routine test with low risk. The Swedish Cardiopulmonary Bioimage Study used CCTA in 25000 participants without known coronary artery disease to study prevalence, severity and characteristics of coronary atherosclerosis.13 Miami Heart Study, a US based cohort of healthy individuals, performed prospective CCTA measurements in over 2500 participants to understand pathophysiology of subclinical atherosclerosis and investigate its role in genesis of clinical cardiovascular disease.14

Linking novel blood-based markers with these refined plaque features by CCTA may provide a better understanding of what is driving the increased coronary heart disease in South Asians and could lead to earlier prevention and treatment. Since South Asians have a 2-fold higher risk of heart disease and comprise \~60% of all heart disease globally, this is a major clinical problem that deserves increased investigation.