Mitral annular calcification

Medical condition

Mitral annular calcification (MAC) is a multifactorial chronic degenerative process in which calcium with lipid is deposited (calcified) in the annular fibrosa ring of the heart's mitral valve. MAC was first discovered and described in 1908 by M. Bonninger in the journal Deutsche Medizinische Wochenschrift. In the majority of cases, affected patients are asymptomatic and the condition is only noted incidentally on echocardiography or computed tomography (CT) scans. However, mitral annular calcification remains clinically significant because while in many cases the calcification is limited to the annulus and proximal leaflet bases, it may also extend further into the valve structure. This may potentially cause mitral regurgitation (MR) or more rarely mitral stenosis (MS), which may produce the classic symptoms of these conditions over time. In addition, calcification of the annulus can inhibit electrical conduction of the AV node, consequently causing various degrees of heart block. While MAC does not usually necessitate treatment independently, the degree of calcification present in the annulus is an important factor in choosing the most appropriate treatment modality for several conditions that do require intervention, particularly those that cause symptomatic obstruction of left ventricular outflow (LVOT).

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