Ethnic differences between extra-coronary measures on cardiac computed tomography: Multi-ethnic study of atherosclerosis (MESA)

Background: Emerging evidence indicates that calcifications in valvular and thoracic aorta are manifestations of generalized atherosclerosis. Assessing the presence and extent of extra-coronary atherosclerosis may further improve prognostic information in subjects who are at risk for cardiovascular disease. The aim of the study is to determine the relative prevalence and quantity of extra-coronary calcifications across ethnic groups in a multi-ethnic population based cohort of asymptomatic individuals. Methods and results: The ethnic differences associated with aortic valve calcification (AVC), mitral valve calcification (MVC), aortic valve root calcification (AVRC) and thoracic aortic wall calcification (TAC) were assessed in 6814 asymptomatic individuals in the multi-ethnic study of atherosclerosis (MESA) study. The overall prevalence of AVC, MVC, AVRC and TAC was 13, 10, 34 and 28%, respectively). As far as the valvular calcifications (AVC, MVC, AVRC) are concerned, the highest prevalence was observed in the Whites, followed by Hispanics and African-Americans with the lowest levels of calcification among the Chinese (all p < 0.001). On the other hand, the Chinese along with Whites had the highest prevalence of TAC (p < 0.001). After adjustment for traditional CVD risk factors and coronary artery calcification, the relative risk of AVC compared with Whites was 0.72 in Blacks (95% CI 0.59-0.90), 1.03 in Hispanics (95% CI 0.82-1.28) and 0.56 in Chinese (95% CI 0.40-0.80). Similar associations were observed for the presence of MVC and AVRC. However, as compared to Whites, the relative risk for presence of TAC was not significantly lower among Hispanics (RR: 0.83, 95% CI: 0.68-1.01) and Chinese Americans (RR: 1.24, 95% CI: 0.95-0.1.62); however Blacks had a significantly lower risk of TAC (RR: 0.50, 95% CI: 0.41-0.60), respectively. Conclusions: Racial differences exist in the prevalence of extra-coronary calcification in a large multi-ethnic population of asymptomatic individuals, thus underscoring the need for developing population specific nomograms to identify overall atherosclerotic burden in a more accurate manner in different ethnic groups. Further studies are needed to assess prognostic potential of each of these new measures of extra-coronary calcification in predicting subsequent cardiovascular events, independently and incrementally above known cardiovascular risk factors and the amount of calcified coronary plaque.