Progression of Mild Mitral Annulus Calcification to Mitral Valve Dysfunction and Impact on Mortality

Abstract

Mitral annulus calcification (MAC) represents a degenerative process resulting in calcium deposition in the mitral valve apparatus. Mitral annulus calcification is associated with adverse clinical outcomes. We sought to examine the long-term significance of mild MAC and its relationship to subsequent mitral valve dysfunction (MVD) and mortality in patients without MVD on the initial echocardiogram. A total of 1,420 patients with mild MAC and no MVD at baseline and 1 or more follow-up echocardiograms at least 1year after the baseline echocardiogram were included in the analysis. For patients with >1 echocardiogram during follow-up, the last echocardiogram was used. The same criteria were used to identify 6,496 patients without MAC. Mitral valve dysfunction was defined as mitral regurgitation (MR) and/or mitral stenosis (MS) of moderate or greater severity. Mixed disease was defined as the concurrent presence of bothmoderate or greater MS and MR. The primary end point was development of MVD, and the secondary end point was all-cause mortality. For patients with mild MAC, age was 74±10years and 528 (37%) were female. Over a median follow-up of 4.7 (interquartile range, 2.7-6.9) years, 215 patients with mild MAC developed MVD, including MR in 170 (79%), MS in 37 (17%), and mixed disease in 8 (4%). In a multivariable regression model compared to patients without MAC, the presence of mild MAC was independently associated with increased mortality (hazard ratio= 1.43; 95% CI 1.24, 1.66; P<.001). Kaplan-Meier 4-year survival rates were 80% and 90% for patients with mild MAC and no MAC, respectively. Mild MAC observed on transthoracic echocardiography is an important clinical finding with prognostic implications for both valvular function and mortality.