Prevalence of coronary artery calcium scores and silent myocardial ischaemia was similar in Indian Asians and European whites in a cross-sectional study of asymptomatic subjects from a UK population (LOLIPOP-IPC)

Background. Coronary heart disease (CHD) mortality is 70% higher among Indian Asians (IA) than European whites (EW), the reasons for this excess remain unexplained. Coronary artery calcification (CAC) is highly correlated with coronary plaque burden and silent myocardial ischaemia in EW; but fails to identify excess risk in IA. We hypothesised that IA have a higher prevalence of silent myocardial ischaemia compared to EW, despite similar CAC, and this may explain their excess CHD mortality. Methods. CAC was measured for 2,369 asymptomatic men and women, aged 35 to 75 years, as part of the London Life Sciences Population (LOLIPOP) study. 518 subjects had CAC scores > 100 Agatston units and of these 256 (49%) patients underwent myocardial perfusion scintigraphy (MPS). Results. CAC scores were similar among IA and EW, after adjustment for conventional risk factors. MPS abnormalities were seen in 56 (22%) subjects. Presence of diabetes (P = .03) and increasing CAC (P < .001) were independent predictors for severity of silent myocardial ischaemia. Ethnicity did not influence the prevalence or the extent of silent myocardial ischaemia. Conclusion. MPS did not identify greater ischaemia among IA compared with EW. This appears incongruent with almost 2-fold higher risk of CHD mortality observed in IA.