Mitral Annular Calcification - MAC

Mitral Annular Calcification or MAC is a significant problem when it involves the majority of the annulus (frame of the mitral valve) posteriorly. This calcium accumulation is more than the deposition of calcium particles, it is the replacement of t…

Mitral Annular Calcification or MAC is a significant problem when it involves the majority of the annulus (frame of the mitral valve) posteriorly. This calcium accumulation is more than the deposition of calcium particles, it is the replacement of the muscle and materials that make the heart in that area with heavy calcium deposits.

Take Home Points:

  1. Mitral annular calcification (MAC) is the deposition of calcium on the annulus of the mitral valve.

  2. Severe MAC poses a significant therapeutic challenge to heart specialists.

  3. Mitral valve replacement is often the therapy of choice in patients with severe MAC.

Mitral annular calcification or MAC occurs mostly in persons in their 70’s or higher. It is not well understood, but its presence can lead to mitral tightening (stenosis) as well as mitral leakage (regurgitation). The problem with MAC is that the calcium starts superficially, but in time it completely replaces the muscle and heart structures it invades. When this happens, removing the calcium can lead to a devastating injury with the back part of the heart separating, something known as atria-ventricular groove dehiscence. For this reason persons with severe MAC are sometimes turned down for surgery.

Mitral annular calcification on a CT scan

 
This computerized tomography study (CT scan) shows the chest of an individual with severe mitral annular calcification (MAC) which is appreciated as a white dense horseshoe area to the right of the image (left of the spine).
 
 

Mitral valve replacement in setting of MAC

 
This video shows a minimally invasive mitral valve replacement using a mechanical mitral valve (graphite based valve) for severe mitral stenosis (too tight of a valve). This operation is of a higher degree of risk give the heavy calcium deposit on the back or posterior flap and the frame or annulus of the mitral valve.