Introduction: In Singapore, the age-standardised event rates of myocardial infarction (MI) are 2- and 3-fold higher for Malays and Indians respectively compared to the Chinese. The objectives of this study were to determine the prevalence and quantity of coronary artery calcification (CAC) and non-calcified plaques across these 3 ethnic groups.Materials and Methods: This was a retrospective descriptive study. We identified 1041 patients (810 Chinese, 139 Malays, 92 Indians) without previous history of cardiovascular disease who underwent cardiac computed tomography for atypical chest pain evaluation. A cardiologist, who was blinded to the patients’ clinical demographics, reviewed all scans. We retrospectively analysed all their case records. Results: Overall, Malays were most likely to be active smokers (P = 0.02), Indians had the highest prevalence of diabetes mellitus (P = 0.01) and Chinese had the highest mean age (P <0.0001). The overall prevalence of patients with non-calcified plaques as the only manifestation of sub-clinical coronary artery disease was 2.1%. There was no significant difference in the prevalence of CAC, mean CAC score or prevalence of non-calcified plaques among the 3 ethnic groups. Active smoking, age and hypertension were independent predictors of CAC. Non-calcified plaques were positively associated with male gender, age, dyslipidaemia and diabetes mellitus. Conclusion: The higher MI rates in Malays and Indians in Singapore cannot be explained by any difference in CAC or non-calcified plaque. More research with prospective followup of larger patient populations is necessary to establish if ethnic-specific calibration of CAC measures is needed to adjust for differences among ethnic groups.
Coronary artery calcification (CAC), as measured by computed tomography (CT), is a surrogate marker of coronary atherosclerosis and has been shown to be predictive of future coronary events. Previous studies on race and CAC have yielded discordant results. The Coronary Artery Risk Development in Young Adults study reported an absence of racial differences in the prevalence and severity of CAC using coronary CT.5 Conversely, the Multi-Ethnic Study of Atherosclerosis has shown that CAC prevalence and amount are heavily influenced by ethnicity, in addition to age and gender.
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