Background: Activation of the complement system after coronary artery bypass graft surgery involves C-reactive protein (CRP). This inflammatory response is related to baseline CRP levels and associated with postoperative arrhythmia, in particular atrial fibrillation (AF). We investigated whether baseline CRP levels are a risk indicator for the occurrence of AF and whether this phenomenon is cardiopulmonary bypass dependent.
Methods: C-reactive protein was measured in perioperative blood samples of patients of the Octopus Study (coronary artery bypass graft surgery with [n = 73] or without cardiopulmonary bypass [n = 79]). Baseline CRP was dichotomized into a low and a high baseline group, using a cutoff value of 3.0 mg/L.
Results: After coronary artery bypass graft surgery with cardiopulmonary bypass 11 of 53 patients (21%) with low preoperative CRP levels had AF versus 11 of 20 patients (55%) with high baseline CRP levels (p = 0.01). In the off-pump group AF occurred in 4 of 52 patients (8%) who had low baseline CRP levels, versus 8 of 27 patients (30%) with high preoperative CRP levels (p = 0.002). After adjusting for age, the odds ratio (95% confidence interval) was 4.6 (1.4 to 15.3) with cardiopulmonary bypass, 3.7 (0.93 to 14.7) in the off-pump group, and 3.3 (1.4 to 7.6) for both groups together. Continuous baseline CRP was an independent predictor for AF in a multivariate logistic regression model (p = 0.02).
Conclusions: Patients with high baseline CRP levels are at higher risk of having postoperative AF in both on-pump and off-pump surgery.