Mitral annular calcification as a predictor of stroke in the multiethnic study of atherosclerosis

BACKGROUND: Mitral annular calcification (MAC) is associated with an increased risk for cardiovascular morbidity and mortality. This study provides recent data on the association between cardiac computed tomography (CT) derived MAC and 15 years of stroke risk in a racially diverse cohort.

METHODS: All multiethnic studies of atherosclerosis participants ( n  = 6814) who completed a cardiac CT at baseline were included in this analysis. MAC score was calculated from cardiac CT using the Agatston and volume score methods. Multivariable Cox proportional hazard regression models were used to compute hazard ratios for the association between MAC and stroke after adjusting for traditional cardiovascular risk factors, inflammatory markers, coronary artery calcium score, atrial fibrillation, and left atrial size.

RESULTS: Overall, 9% of participants (644/6814) had MAC at baseline. Over a surveillance period of 15 years, 304 strokes occurred, and 79% were ischemic strokes. After adjusting for age, sex, race/ethnicity, SBP, diabetes, smoking, fibrinogen, IL-6, high-sensitivity C-reactive protein, and coronary artery calcium score, baseline MAC was associated with increased risk for all strokes [hazard ratio 1.68; 95% confidence interval (CI) 1.22-2.30: P  = 0.0013]. When atrial fibrillation/flutter and left atrial size were included in the final multivariable model, MAC remained a predictor of all strokes (hazard ratio 1.93; 95% CI 1.22-3.05: P  < 0.0051) and ischemic stroke (hazard ratio 2.03; 95% CI 1.24-3.31: P  < 0.0046).

CONCLUSION: MAC is an independent predictor of long-term stroke risk in a racially diverse population beyond conventional cardiovascular risk factors and atrial fibrillation.