Mitral Annular Calcification, a Not So Marginal and Relatively Benign Finding as Many of Us Think: A Review

Mitral annular calcification (MAC) is usually considered an incidental, benign, age-related finding without serious complications in patients evaluated for cardiovascular or pulmonary disease with imaging studies that may result in mitral regurgitation or stenosis when severe. Therefore, it is usually not considered a significant alteration. However, there is accumulating evidence that it is associated with a higher risk of cardiovascular events, such as atherosclerotic coronary artery disease, aortic artery disease, carotid artery disease, peripheral artery disease, stroke, atrial fibrillation, atrioventricular and/or intraventricular conduction disturbance, systemic embolization, infective endocarditis, heart failure and mortality. The presence of MAC also significantly influences the outcome of mitral valve transcatheter and surgical interventions. Several conditions may predispose to MAC. MAC is strongly related to cardiovascular risk factors, such as hypertension, diabetes, smoking and cardiovascular atherosclerosis, and inflammation may also play a role in the pathogenesis of MAC. Also, conditions that increase mitral valve stress, such as hypertension, aortic stenosis and hypertrophic cardiomyopathy, predispose to accelerated degenerative calcification of the mitral annulus area. Congenital disorders, e.g., Marfan syndrome and Hurler syndrome, are also associated with MAC, due to an intrinsic abnormality of the connective tissue composing the annulus.