Background Mitral annular calcification (MAC) is a chronic degenerative process that may progress. This study aimed to investigate associating factors and clinical implications of MAC progression. Methods and Results Among 560 patients with MAC identified by transthoracic echocardiography between January 2012 and June 2016, 138 patients (mean±SD age 72.7±10.2 years, 73 women) with mild or moderate MAC who received follow-up examination within 18 to 36 months were retrospectively analyzed. Progressive MAC was defined as hemodynamic or structural profiles that had worsened by more than 1 grade. Hemodynamic features were assessed by the transmitral mean diastolic pressure gradient (MDPG), and structural features were assessed by the MAC angle in the parasternal short-axis view. The clinical outcome was defined as a composite of all-cause mortality, hospitalization for heart failure, and occurrence of ischemic stroke. Forty-three patients (31.2%) showed progressive MAC. Patients with progressive MAC had higher systolic blood pressure, pulse pressure, MAC angle, and MDPG than those with stable MAC. Patients with progressive MAC had smaller left ventricular (LV) end-systolic dimensions and higher LV ejection fractions compared with those with stable MAC. In multivariate analysis, pulse pressure, LV ejection fraction, MAC angle, and MDPG at baseline were significantly associated with MAC progression. During a median of 39.2 months' follow-up, patients with progressive MAC showed poorer clinical outcomes than those with stable MAC (log-rank P=0.015). Conclusions MAC progression is not rare and is associated with structural substrate and hemodynamic loads that result in mechanical stress. Patients with progressive MAC have poor outcomes.
Keywords: mitral annular calcification; outcome; progression; risk factor.