Mitral annular calcification

Mitral annular calcification (MAC) refers to deposition of calcium (along with lipid) in the annular fibrosa of the mitral valve.

Annular calcification is seen in up to 35% of elderly patients. It is common in females over 65 years, in those with myxtomatous degeneration of the mitral valve and those with elevated left ventricular pressures.

Although annular calcification is associated with mitral regurgitation, this is usually trivial and asymptomatic. Calcification of the annulus can however impede AV nodal conduction and therefore lead to varying degrees of heart block

Pathologically it is important to distinguish annular calcification from mitral valve leaflet calcification. In annular calcification, the diseased annulus is covered with intact endothelium. 

Compared to aortic valve calcification, calcification of the mitral annulus is not significantly associated with stenosis of the valve and it is no longer felt to represent an independent risk factor for stroke 1.

It is also associated with an increased prevalence of severe obstructive coronary artery disease particularly in older (>65 years) age groups 2.

On a frontal chest radiograph, calcification is demonstrated in the expected location of the mitral valve.  It typically begins around the margins of the posterior leaflet forming a "J" or "C", eventually with anterior leaflet involvement the "C" closes forming an "O".

CT is more sensitive for calcification of the annulus although it depends on the degree of motion artefact (which is a factor of heart rate and scan time).

Annular calcification per se does not require any treatment. Instead, patients are managed according to the presence of heart block, mitral regurgitation (usually minimal) and other cardiovascular signs and symptoms. 

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Article information

rID: 1684
Systems: Chest, Cardiac
Synonyms or Alternate Spellings:
  • Mitral annular calcification (MAC)
  • Mitral valve annular calcification (MVAC)
  • MVAC

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Cases and figures

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    Figure 1: gross pathology
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    Mitral valve calc...
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    Case 5 : axial 3D heart
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