MAC primarily involves which structure of the mitral apparatus?

MAC primarily involves which structure of the mitral apparatus?

• A. Left atrial appendage
• B. Papillary muscles
• C. Interventricular septum
• D. Mitral annulus

Answer: (D)

Mitral annular calcification targets the fibrous ring that forms the base of the mitral valve—the mitral annulus. This annulus anchors the mitral leaflets and helps seal the valve during systole. Calcification stiffens and can distort the annulus, potentially causing mitral valve dysfunction (stenosis or regurgitation). The other structures listed aren’t the primary site of MAC: the left atrial appendage is a separate cavity, the papillary muscles are part of the subvalvular apparatus (anchoring the chordae), and the interventricular septum is a ventricular structure not involved in the annular calcification. On imaging, MAC appears as a bright, irregular density along the annular region, usually posteriorly.

Mitral annular calcification targets the fibrous ring that forms the base of the mitral valve—the mitral annulus. This annulus anchors the mitral leaflets and helps seal the valve during systole. Calcification stiffens and can distort the annulus, potentially causing mitral valve dysfunction (stenosis or regurgitation). The other structures listed aren’t the primary site of MAC: the left atrial appendage is a separate cavity, the papillary muscles are part of the subvalvular apparatus (anchoring the chordae), and the interventricular septum is a ventricular structure not involved in the annular calcification. On imaging, MAC appears as a bright, irregular density along the annular region, usually posteriorly.