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

Background Mitral annulus calcification (MAC) represents a degenerative process resulting in calcium deposition in the mitral valve apparatus. MAC 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. Methods A total of 1420 patients with mild MAC and no MVD at baseline, and one or more follow-up echocardiograms at least one year 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 6496 patients without MAC.Mitral valve dysfunction (MVD) was defined as mitral regurgitation (MR) and/or mitral stenosis (MS) of ≥moderate severity. Mixed disease was defined as the concurrent presence of both ≥ moderate MS and MR. The primary endpoint was development of MVD, and the secondary endpoint was all-cause mortality. Results For patients with mild MAC, age was 74±10 years and 528 (37%) were female. Over a median follow-up of 4.7 (IQR 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% confidence interval: 1.24, 1.66, p<0.001). Kaplan-Meier 4-year survival rates were 80% and 90% for patients with mild MAC and no MAC, respectively. Conclusions Mild MAC observed on transthoracic echocardiography is an important clinical finding with prognostic implications for both valvular function and mortality.