Mitral annular calcification progression and the risk of atrial fibrillation: results from MESA

To determine if progression of mitral annular calcium (MAC) detected by cardiac computed tomography (CT) predicts incident atrial fibrillation (AF).

This analysis included 5683 participants (mean age 64 ± 10 years; 52% women; 40% whites; 27% blacks; 21% Hispanics; 12% Chinese–Americans) from the Multi-Ethnic Study of Atherosclerosis. MAC was measured by cardiac CT at baseline and at a follow-up CT scan over a mean time of 2.4 ± 0.84 years. AF was ascertained by review of hospital discharge records and from Medicare claims data through 31 December 2012. Cox regression was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between MAC progression and AF. Over a median follow-up of 8.6 years, a total of 533 (9.4%) incident AF cases were detected. In a model adjusted for age, sex, race/ethnicity, education, income, baseline MAC, systolic blood pressure, body mass index, diabetes, smoking, total cholesterol, high-density lipoprotein cholesterol, antihypertensive medications, lipid-lowering therapies, and aspirin, any MAC progression (>0/year) was associated with an increased risk for AF (HR = 1.50, 95% CI = 1.20–1.87). Multiplicative interactions were not significant between MAC progression and AF by age (<65 year vs. older), sex, or race/ethnicity (whites vs. non-whites).

Important prognostic information regarding AF risk is obtained with follow-up MAC measurement, as the risk for participants with any MAC progression was substantively greater than participants without progression. MAC progression may detect underlying left atrial abnormalities that predispose to AF.