Predictors of Postoperative Atrial Fibrillation in Patients with Coronary Artery Disease Undergoing Cardiopulmonary Bypass: A Possible Role for Myocardial Ischemia and Atrial Inflammation

OBJECTIVE: To evaluate the preoperative presence of C-reactive protein (CRP) and troponin T(hs-TnT) in patients with coronary artery disease (CAD) undergoing cardiopulmonary bypass (CPB) in order to better clarify the role of atrial inflammation and/or myocardial ischemia in the development of postoperative atrial fibrillation (POAF). DESIGN: Prospective, nonrandomized study. SETTING: University hospital. PARTICIPANTS: Thirty-eight consecutive ischemic patients admitted to the authors' hospital for CAD undergoing elective on-pump coronary artery bypass grafting (CABG). INTERVENTION: Elective on-pump CABG. MEASUREMENTS AND MAIN RESULTS: Peripheral blood samples were collected from all patients before and 24 hours after CABG to assess high sensitive (hs)-CRP and troponin T (hs-TnT) levels. The patients' heart rhythm was monitored by continuous ECG telemetry. Biopsies from the right atrial appendage were obtained at the beginning of the CABG procedure in order to perform immunohistochemistry for CRP and reverse transcription polymerase chain reaction for CRP mRNA expression. Fourteen patients out of 38 (36%) developed POAF. Atrial CRP was found in 31 patients (82%), 10 with POAF and 21 with sinus rhythm (71% v 87% respectively, p = ns). None of the atrial samples was positive for CRP mRNA. Atrial CRP did not correlate with serum hs-CRP levels and with occurrence of POAF, but with the incidence of diabetes (p = 0.010). Postoperative hs-TnT levels, but not hs-CRP levels, were identified as the only predictor of POAF occurrence (p = 0.016). CONCLUSIONS: In patients undergoing CABG, neither peripheral nor tissue preoperative CRP levels, but only postoperative hs-TnT levels, correlated with POAF, suggesting the primary role of an ischemic trigger of atrial fibrillation