Relation of mitral annular calcium and coronary calcium (from the multi-ethnic study of atherosclerosis [MESA])

Atherosclerosis is a complex diffuse disorder. The close correlation between coronary artery calcium (CAC) score on computed tomogram and extent and severity of coronary atherosclerosis is well established. It has been suggested that mitral annular calcification (MAC) may be a manifestation of generalized atherosclerosis. The MESA population included a population-based sample of 4 ethnic groups (12% Chinese, 38% white, 22% Hispanic, and 28% black) of 6,814 women and men 45 to 84 years of age. Computed tomographic scans were performed for all participants. The calcium score of each lesion was calculated by multiplying lesion area by a density factor derived from maximal Hounsfield units. A total calcium score was determined by summing individual lesion scores at each anatomic site. Relative risk regression was used to model the probability of MAC as a function of CAC >0 and CAC categories (0, 1 to 99, 100 to 399, and <400) with the referent group being CAC 0. The final study population consisted of 6,814 subjects (mean age 62 ± 10 years, 47% men). Overall 9% and 50% had detectable MAC and CAC, respectively. Of those with absent CAC, only 4% had MAC, whereas 9%, 19%, and 15% had MAC scores with increasing CAC scores of 1 to 99, 100 to 399, and <400, respectively (p <0.0001 for trend). After taking into account demographics and other risk factors, the prevalence ratio of MAC in those with mild CAC (1 to 99) was 2.13 (95% confidence interval 1.69 to 2.69) and increased to 7.57 (95% confidence interval 5.95 to 9.62) for CAC <400. Similar statistically significant increased risk of MAC was found when CAC was assessed as a continuous variable. In conclusion, we observed a strong association between MAC and increasing burden of CAC. This association weakened but persisted after adjustment for age, gender, and other traditional cardiovascular risk factors. These findings suggest that presence of MAC is an indicator of atherosclerotic burden rather than just a degenerative change of the mitral valve.