Coronary artery calcium and risk of atrial fibrillation (from the multi-ethnic study of atherosclerosis)

Calcified coronary arteries are associated with the development of cardiovascular disease and stroke. It is currently unknown whether coronary artery calcium (CAC) is associated with an increased risk for atrial fibrillation (AF). The aim of this study was to address this question in 6,641 participants (mean age 62 ± 10 years, 53% women, 62% nonwhites) from the Multi-Ethnic Study of Atherosclerosis (MESA) who were free of baseline clinical cardiovascular disease and AF. CAC measurements were assessed by cardiac computed tomography at study baseline. AF was ascertained by review of hospital discharge records and from Medicare claims data until December 31, 2010. Cox regression was used to compute hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the association between CAC and AF. During a median follow-up period of 8.5 years, 308 participants (4.6%) developed AF. In a model adjusted for sociodemographics, cardiovascular risk factors, and potential confounders, higher CAC scores were associated with increased risk for AF (CAC = 0: HR 1.0, referent; CAC = 1 to 100: HR 1.4, 95% CI 1.01 to 2.0; CAC = 101 to 300: HR 1.6, 95% CI 1.1 to 2.4; CAC >300: HR 2.1, 95% CI 1.4 to 2.9). The addition of CAC to the Framingham Heart Study and Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) AF risk scores yielded integrated discrimination improvement of 0.0033 (95% CI 0.0015 to 0.0066) and 0.0028 (95% CI 0.0012 to 0.0057), with relative integrated discrimination improvement of 0.10 (95% CI 0.061 to 0.15) and 0.077 (95% CI 0.040 to 0.11), respectively. In conclusion, CAC is independently associated with increased risk for AF.