Differences in risk factors associated with the initiation and progression of mitral annular calcification in asymptomatic individuals

Abstract

Mitral annular calcification (MAC) is hypothesized to be a representation of atherosclerosis and is associated with adverse outcomes. However, the pathophysiology and risk factors associated with MAC development are not fully understood. Using the KOrea Initiatives on Coronary Artery (KOICA) registry, 738 asymptomatic individuals who underwent health screening with echocardiography and serial cardiac computed tomography (CT) were included for analysis. MAC was identified on CT, and the severity was quantified using Agatston units (AU). Risk factors associated with prevalent MAC and the rate of MAC progression were identified using multivariable regression models. On initial CT, 52 (7.0%) participants showed prevalent MAC, and in this group the median MAC progression rate was 3.4 AU/year (interquartile range: 0.2-14.7) during a median interscan duration of 36.4 months. Factors associated with prevalent MAC were older age (p < 0.001), higher body-mass index (p = 0.04), diabetes (p < 0.01), higher systolic blood pressure (p < 0.01), and higher left atrial volume index (p = 0.02). Meanwhile, factors associated with faster MAC progression were initial MAC severity (p < 0.001), male sex (p < 0.01), and higher serum phosphate (p < 0.001). Traditional atherosclerotic risk factors have an important role in the initial process of MAC development. The association between left atrial volume index and prevalent MAC further suggests the implication of elevated left ventricular filling pressure in MAC initiation. Conversely, initial MAC severity and mineral metabolism were found to be major determinants in the later phase of MAC progression.