Implications of the 2019 American College of Cardiology/American Heart Association Primary Prevention Guidelines and potential value of the coronary artery calcium score among South Asians in the US: The Mediators of Atherosclerosis in South Asians Living in America (MASALA) study

Background and aims: South Asian (SA) ethnicity is associated with an increased risk of atherosclerotic cardiovascular disease (ASCVD). However, the implications of considering SA ethnicity as a “risk-enhancing factor” per recent American College of Cardiology/American Heart Association guidelines are not fully understood. Methods: We used data from the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study, a community-based cohort study of individuals of SA ancestry living in the US. The Pooled Cohort Equations were used to estimate 10-year ASCVD risk. Metabolic risk factors and coronary artery calcium (CAC) scores were assessed. Results: Among 1114 MASALA participants included (median age 56 years, 48% women), 28% were already using a statin at baseline, 25% had prevalent diabetes, and 59% qualified for 10-year ASCVD risk assessment for statin allocation purposes. The prevalence of low, borderline, intermediate, and high estimated ASCVD risk was 65%, 11%, 20% and 5%, respectively. Among participants at intermediate risk, 30% had CAC = 0 and 37% had CAC>100, while among participants at borderline risk, 54% had CAC = 0 and 13% had CAC>100. Systematic consideration of intermediate and, particularly, of borderline risk individuals as statin candidates would enrich the statin-consideration group with CAC = 0 participants up to 35%. Prediabetes and abdominal obesity were highly prevalent across all estimated risk strata, including among those with CAC = 0. Conclusions: Our findings suggest that systematic consideration of borderline risk SAs as statin candidates might result in considerable overtreatment, and further risk assessment with CAC may help better personalize statin allocation in these individuals. Early, aggressive lifestyle interventions aimed at reducing the risk of incident diabetes should be strongly recommended in US SAs, particularly among those considered candidates for statin therapy for primary prevention. Longitudinal studies are needed to confirm the favorable prognosis of CAC = 0 in SAs.