Where does MAC occur?

Where does MAC occur?

• A. Annulus
• B. Leaflets
• C. LV wall
• D. Papillary muscles

Answer: (A)

Mitral annular calcification involves the fibrous ring that forms the mitral valve annulus. It shows up on ultrasound as a dense, bright, curvilinear line along the base of the valve where the leaflets attach, typically more prominent on the posterior annulus. This location—along the annulus itself—is what distinguishes MAC from calcification of the leaflets, the LV wall, or papillary muscles. The calcification can cause acoustic shadowing and may be associated with changes in valve function if extensive, but the defining feature is its position in the annulus rather than the other structures.

Mitral annular calcification involves the fibrous ring that forms the mitral valve annulus. It shows up on ultrasound as a dense, bright, curvilinear line along the base of the valve where the leaflets attach, typically more prominent on the posterior annulus. This location—along the annulus itself—is what distinguishes MAC from calcification of the leaflets, the LV wall, or papillary muscles. The calcification can cause acoustic shadowing and may be associated with changes in valve function if extensive, but the defining feature is its position in the annulus rather than the other structures.