Mitral annular calcification

Last revised by Craig Hacking on 17 Apr 2024

Mitral annular calcification refers to the 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 myxomatous degeneration of the mitral valve and those with elevated left ventricular pressures.

It is also associated with an increased prevalence of severe obstructive coronary artery disease particularly in older (>65 years) age groups 2. It is more often seen in patients with chronic renal failure.

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. Calcification of the leaflets can cause mitral stenosis.

Pathologically it is important to distinguish annular calcification from mitral valve leaflet calcification. In annular calcification, the diseased annulus is covered with intact endothelium. It can also undergo caseous necrosis and embolize to the brain.

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.

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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