AIMS: Postoperative atrial fibrillation (POAF), a common complication following coronary artery bypass graft (CABG) surgery, is associated with increased morbidity and mortality. Inflammation may be an important factor for the pathogenesis of POAF, and increased preoperative levels of C-reactive protein (CRP) are associated with the development of POAF. However, the relationship between postoperative CRP and POAF is less well established.

METHODS AND RESULTS: Patients undergoing first-time isolated CABG surgery (1 January 2000-31 December 2016) were identified using the Eastern Danish Heart Surgery Database and nationwide administrative registries. Patients with no history of atrial fibrillation and with available CRP measurements from postoperative day (POD) 4 were included. The study population was divided into quartiles based on CRP. The association between CRP levels and the odds of developing POAF was investigated using multivariable logistic regression analysis. We included 6711 patients. The CRP intervals on POD 4 for the CRP groups (lowest to highest) were ≤90, >90 to ≤127, >127 to ≤175, and >175 mg/L, respectively. Patients in the highest CRP group were older and more often men compared with patients in the lowest CRP group [median age 67 years (P25-P75: 61-73) and 84.7% men vs. median age 64 years (P25-P75: 56-70) and 77.9% men]. In the lowest and highest CRP groups, 25% and 35% developed POAF, respectively. In adjusted analysis, the highest CRP group, compared with the lowest CRP group, was associated with greater odds of developing POAF (odds ratio 1.31; 95% confidence interval 1.12-1.54).

CONCLUSION: Increased postoperative CRP levels after CABG surgery was associated with the development of POAF.