The prevalence of mitral valve disease with mitral annular calcification (MAC) and its clinical outcomes remain uncertain. This study sought to evaluate the prevalence of significant mitral disease due to MAC, and the impact of intervention on the clinical outcomes in these patients. All patients who underwent transthoracic echocardiography (TTE) between January 2014 and December 2015 in our health care system were reviewed and identified for having MAC with significant mitral valve disease (i.e., either >= moderate mitral regurgitation (MR) or mitral stenosis (MS)). The primary endpoints of the study were all-cause mortality and a composite outcome of mortality or heart failure hospitalization at 3-year follow-up. Of 41,136 patients who underwent TTE, MAC was identified in 2,855 (6.9%) patients, including 434 (1.1% of total) patients who had significant MR and/or MS (median age [IQR], 80 [73 to 87] years; 63% women). MAC predominately involved the posterior annulus (95%), with the majority having calcification of both trigones (55%), the leaflets (71%), and circumferential involvement (67%). During 3-year follow-up, 59 (14%) patients underwent surgical or transcatheter MV intervention. Patients who did not undergo mitral intervention had higher all-cause mortality (HR 2.80, 95% CI 1.60 to 4.92; p<0.001) and a greater risk of the composite outcome (HR 1.43, 1.00 to 2.04; p = 0.05) than those treated. Survival at 3-year follow-up was markedly greater in those with mitral intervention (78% vs 50%; p<0.001). This survival benefit remained after multivariable adjustment. In conclusion, MAC affects approximately % of patients who undergo echocardiography. Those with significant mitral valve disease due to any degree of MAC have poor survival, which may be ameliorated with transcatheter or surgical intervention. (C) 2022 Elsevier Inc. All rights reserved.