Preoperative C-reactive protein and atrial fibrillation after off-pump coronary bypass surgery

OBJECTIVE: The purpose of the present study was to investigate the association between preoperative C-reactive protein (CRP) and atrial fibrillation (AF) after isolated off-pump coronary bypass surgery. METHODS: Of 683 consecutive patients undergoing isolated coronary bypass surgery by a single surgeon between January 2002 and March 2009, 552 were retrospectively analyzed after excluding the following 131 cases: on-pump surgery (n = 6), chronic AF (n = 14), pacemaker rhythm (n = 7), and preoperative CRP of ≥ 10 mg l(-1) (n = 104). We analyzed the correlation on a continuous basis per 1 SD increase in the logarithmically transformed value of CRP and on a group basis CRP level categorized into three groups: <1.0 mg l(-1), n = 196; 1.0-3.0 mg l(-1), n = 220; and 3.0-10.0 mg l(-1), n = 136. RESULTS: AF occurred in 121 patients (21.9%, 121/552) of patients after surgery. The median value (interquartile range) of preoperative CRP (mg l(-1)) was significantly higher in patients who developed AF than in those who did not (2.2 (1.0-4.2) vs 1.3 (0.6-2.5), p = 0.001). The rate of 7-day survival free from AF was 65.4% in patients with CRP of 3.0-10.0 mg l(-1), 79.9% in those with CRP of 1.0-3.0 mg l(-1), and 85.7% in those with CRP of <1.0 mg l(-1) (log-rank test: p = 0.001). The unadjusted hazard ratio (95% confidence interval) for the association between CRP and postoperative AF was 1.65 (1.32-2.06) per 1 SD increase and 3.17 (1.86-5.40) for patients with CRP of 3.0-10.0 mg l(-1) versus those with levels of <1.0 mg l(-1). This association persisted after adjustment for the univariate predictors (1.43 (1.22-1.97) per 1 SD increase; 2.88 (1.67-4.97) for patients with CRP of 3.0-10.0 mg l(-1) vs <1.0 mg l(-1)) or the known risk factors (1.34 (1.18-1.86) per 1 SD increase; 2.52 (1.54-4.36) for patients with CRP of 3.0-10.0 mg l(-1) vs <1.0 mg l(-1)). The area under the receiver operating characteristic curve (95% confidence interval) for preoperative CRP as a predictor of postoperative AF was 0.68 (0.62-0.74) (p = 0.001). CONCLUSIONS: Preoperative CRP is independently associated with the occurrence of AF after isolated off-pump coronary bypass surgery.