Coronary artery calcium score and the long-term risk of atrial fibrillation in patients undergoing non-contrast cardiac computed tomography for suspected coronary artery disease: a Danish registry-based cohort study

Aims To examine the association between coronary artery calcium score (CACS) and risk of future atrial fibrillation (AF), and to estimate the predictive accuracy of CACS for AF development in patients undergoing non-contrast cardiac computed tomography (nCCT). Methods We conducted a registry-based cohort study of 27 962 patients suspected of having coronary artery disease and and results without history of AF who were identified in the Western Denmark Heart Registry. The patients underwent nCCT between 2010 and 2015 and were followed until 2016 (median 2.9 years). CACSs were determined using nCCT. We used Cox proportional hazards models to estimate hazard ratios (HR) with 95% confidence intervals (CI). A receiver operating characteristic (ROC) curve for AF was used to assess the predictive accuracy of CACS. Among the patients, 52% had a CACS of 0, 26% of 1-99, 13% of 100-399, 6% of 400-999, and 4% of >_ 1000. AF occurred in 622 patients after nCCT, corresponding to an overall incidence rate of 7.5 (95% CI: 6.9-8.1) per 1000 person-years. After multivariable adjustment, the HRs (95% CIs) were (ref. CACS 0) CACS 1-99: 1.00 (0.80-1.25); CACS 100-399: 1.36 (1.06-1.74); CACS 400-999: 1.76 (1.33-2.35); and CACS >_ 1000: 1.67 (1.20-2.34). An ROC curve showed an area under the curve of 0.68 (0.65-0.71) for the prediction of AF within one year after nCCT. Conclusion A high CACS is associated with a high risk of subsequent AF development and may have potential to guide future follow-ups for AF detection after CACS measurement in order to identify AF patients earlier.