(VP065) INCIDENCE, RECURRENCE, AND ETHNICITY SPECIFIC RISK FACTORS FOR PREMATURE CORONARY ARTERY DISEASE IN SOUTH ASIANS AND CAUCASIANS.

Background: The incidence of premature coronary artery disease (CAD) is increasing globally. South Asians have a disproportionately higher burden of atherosclerotic cardiovascular disease (ASCVD) compared to Caucasians. However, the effect of South Asian ethnicity on the risk of recurrent events in individuals with premature ASCVD has not been prospectively evaluated.

METHODS AND RESULTS: Patients in the SAVEBC and UK biobank (UKB) registries were enrolled and stratified by ethnicity and presence of premature CAD. The co-primary outcomes were to compare proportion of premature CAD in South Asians and Caucasians, and the incidence of recurrent ASVCD events. Secondary outcomes included describing demographic, physical, biochemical and exploratory variables in South Asians compared to Caucasians with premature CAD. 11,265 participants were included, 1,129 (143 South Asian; 21%) were from SAVEBC and 10,007 (400 South Asian; 4.0%) from UKB. There was a significantly higher proportion of premature CAD in South Asians compared to Caucasians in UKB (5.2% vs. 2.0%, p < 0.001) (Figure 1). Similarly South Asians were overrepresented in SAVEBC (21% of cohort vs. 7.9% of British Columbia population). South Asians compared to Caucasians with premature CAD had increased prevalence of diabetes (SAVEBC: 20.1% vs 13.8%, p=0.08; UKB: 37.5% vs 18.0%, p< 0.001), and lower mean HDL cholesterol (SAVEBC: 1.4±0.4 vs 1.5±0.4, p=0.21; UKB: 1.1±0.3 vs 1.2±0.3, p< 0.001). South Asians also had more diffuse disease as reflected by more coronary segments affected (4.9±3.0 vs. 4.1±2.6, p=0.05), and a trend towards more affected coronary vessels compared to Caucasians (1.31±1.4 vs. 0.61±0.91, p=0.14). In patients with premature CAD, there was a significantly higher incidence of recurrent ASCVD events (HR 1.35, 95% CI 1.13,1.61, p< 0.001) in South Asians (Figure 2), with a shorter time to recurrent ASCVD event compared to Caucasians (5.3±8.1years vs. 7.7±10.1years, p< 0.001). South Asian ethnicity remained a significant predictor of recurrent events on multivariate analysis (HR 1.24, 95% CI 1.03,1.48, p=0.02).

Conclusion: Using two prospective registries, South Asians had a higher proportion of premature CAD compared to Caucasians, as well as a higher risk of recurrent cardiovascular events with shorter time to recurrent events. Some of this increased risk may be explained by an adverse cardiometabolic risk profile, however there are likely mechanisms of risk that have yet to be elucidated. Understanding these unique mechanisms of cardiovascular risk in the South Asian population is critical to appropriate identification of high-risk individuals and initiation of contemporary preventative therapies.