Mitral annular calcification as a cause of mitral valve gradients.

Background: Mitral annular calcification (MAC) is common, particularly in the elderly. While thought to occasionally produce significant mitral regurgitation, it is considered a rare cause of mitral stenosis.

Methods: Echocardiogram reports from general cardiology outpatients were searched for phrases regarding severe MAC and, separately, for mitral stenosis. Rheumatic disease or other mitral valve (MV) pathology was excluded. Mean MV and aortic valve (AV) gradients were recorded. The presence or absence of anterior MAC was noted and a semi-quantitative assessment of anterior mitral leaflet (AML) mobility was made. Ten patients with annuloplasty rings served for comparison.

Results: Group A (22 patients with moderately/severely reduced AML mobility) had a mean MV gradient of 7 mm Hg (range 3-14) vs. 3 mm Hg (range 1-5) in group B (21 patients with normal/mildly reduced AML mobility), p<0.0001. Annuloplasty patients had a mean MV gradient of 3 mm Hg, p<0.001 vs. group A but similar to group B. Mean AV gradient was 27 mm Hg (range 4-48) in group A vs. 14 mm Hg in group B (range 3-40), p=0.013. No patient had more than mild mitral regurgitation.

Conclusion: MAC producing a potentially important MV gradient is not rare in the general cardiology population. Reduced AML mobility appears to be necessary for a gradient >5 mm Hg. Significant AV gradients are commonly associated, reflecting greater overall cardiac calcification. These patients can be easily identified by looking for reduced AML mobility as part of widespread cardiac calcification.