Mitral annular calcification, coronary artery calcification, and risk of incident atrial fibrillation in the multi-ethnic study of atherosclerosis (MESA)

BACKGROUND: Coronary artery calcification (CAC) and mitral annular calcification (MAC) reflect cardiovascular aging and systemic atherosclerosis and have each been associated with the risk of atrial fibrillation (AF). OBJECTIVE: To examine the joint associations of CAC and MAC with incident AF in the Multi-Ethnic Study of Atherosclerosis (MESA). METHODS: CAC and MAC were assessed using cardiac computed tomography and quantified by Agatston scoring. Participants were categorized into four groups: no CAC and no MAC (reference), CAC present without MAC, MAC present without CAC, both CAC and MAC present. Incident AF was identified through hospitalization records and Medicare claims. Multivariable-adjusted Cox proportional hazards models examined the association between CAC/MAC categories and incident AF. Improvement in AF risk prediction with the addition of CAC and MAC to Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE-AF) risk score was assessed using Harrell's C-statistic. RESULTS: Among 6588 participants (mean age 62 ​± ​10 years; 53% female) free of baseline AF, 1306 incident AF events occurred over a median follow-up of 16.5 years. Participants with both CAC and MAC present had the highest risk of AF. Compared with the reference group, CAC present without MAC, MAC present without CAC, and both CAC and MAC present were associated with 39%, 74%, and 96% higher risks of incident AF, respectively. Addition of CAC and MAC improved discrimination of the CHARGE-AF model (C-statistic 0.746 to 0.754; p ​< ​0.01). CONCLUSIONS: CAC and MAC were jointly associated with incident AF, and their inclusion in a risk score improved AF risk prediction.