Calcification of the mitral annulus and its complications.

Mitral annulus calcification (MAC) is a common cardiac abnormality previously considered to be of little significance. More recently several potentially fatal complications have been recognized and presentation as sudden death described. These complications include cardiac arrhythmias, mitral incompetence, calcific and thromboemboli, bacterial endocarditis, and mitral stenosis. The spectrum of pathological changes seen in MAC, their possible significance, and the features which allow distinction from other mitral valve diseases are reviewed.