We read with interest the report “Relation of Mitral Annular Calcium and Coronary Calcium (from the Multi-Ethnic Study of Atherosclerosis [MESA])” in the May 1, 2011, issue of The American Journal of Cardiology . As the investigators clearly demonstrate, mitral annular calcium (MAC) is associated with coronary artery calcium (CAC) and thereby coronary atherosclerosis. We agree that this finding, commonly noted on cardiac computed tomography, should figure more prominently in the clinical evaluation and management of patients. However, as pointed out by Roberts, MAC is only part of the picture; it is frequently associated with calcific deposits in other structures, such as the submitral apparatus and the aortic root and valve. Conversely, patients may have a heavy burden of calcium (especially in the aortic valve), with little or no detectable calcium in the mitral annulus. Focusing on MAC alone underestimates the extent of the calcium.

We would also like to point out that MAC is most frequently detected on echocardiography, although currently, there is no echocardiographic standard for its evaluation. Various methods have been reported, most of them not very sophisticated. Most do not consider calcium of other cardiac structures. Accounting for calcium in all these areas, rather than limiting our examination to the mitral annulus, should allow better prediction of CAC. In a small series of patients with cardiac computed tomographic scans, we observed a significant correlation between global cardiac calcium and CAC as measured by the Agatston score. In addition, we tested an echocardiographic score that semiquantitatively measures global cardiac calcium and found that this score too was useful in predicting CAC. In fact, a high echocardiographic score had a positive predictive value of 60% for a CAC score >400 (consistent with severe coronary atherosclerosis). In this study, the global calcium score performed better than MAC alone.