Mitral annular calcification as a cause of mitral valve gradients
Introduction
Mitral annular calcification (MAC) is a common finding on echocardiography, particularly in the elderly [1]. The etiology is unclear although it is associated with the same risk factors as atherosclerotic disease of which it may be a subclinical form [2]. In addition it appears to be related to abnormal calcium and phosphorus metabolism with a high incidence noted in end-stage renal disease [3].
Generally, this process is regarded as benign although it is thought to produce significant mitral regurgitation on occasion [4]. Mitral stenosis due to annular calcification is reported to be quite rare [5], [6], [7], [8], [9], [10], [11], [12], [13]. However, we have noted a number of patients undergoing routine echocardiography who have a significant resting gradient across the mitral valve (MV) with the only apparent etiology being MAC. We therefore evaluated a series of echocardiograms demonstrating severe MAC for features associated with a resting MV gradient.
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Materials and methods
Outpatient echocardiogram reports were searched for key phrases regarding severe annular calcification and, separately, for mitral stenosis; patients with rheumatic disease or other identifiable mitral valve disease were excluded. All outpatient studies were performed in the setting of a private general cardiology practice between 1/1/03–10/1/05. Several inpatient studies were included as they came to our attention for purposes of substantiating our observations. Forty-three cases (40
Results
A total of 4270 patients underwent echocardiography in our outpatient lab over this time period. Of those, 3096 were age 65 or older. Forty patients were reported to have severe MAC, representing 0.9% of the total group and 1.3% of those 65 and over. All but three had severe posterior MAC. Nineteen subjects were identified who had reduced AML mobility due to annular calcification (group A included these as well as three additional inpatients). They represented 0.4% of the total number of
Discussion
Mitral annular calcification is commonly observed on echocardiograms, particularly in the elderly [1]. While this is usually an incidental finding it has occasionally been associated with significant mitral regurgitation [4]. As demonstrated in our cohort of unselected outpatients it can also produce a clinically relevant resting gradient across the mitral valve, with approximately 0.5% of our outpatients affected. This is more likely when the MAC is severe and especially when there is reduced
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