BACKGROUND: Postoperative atrial fibrillation (AF) plays a major role in the determination of hemodynamic deterioration and can be associated with cardiovascular events after coronary artery surgery. Elevated interleukin (IL)-6 and C-reactive protein (CRP) levels in patients with AF suggest a role of inflammation in the pathogenesis of AF. We conducted a study to investigate the correlation between postoperative AF and IL-6 and high-sensitivity CRP (hsCRP). MATERIALS AND METHODS: Forty-nine patients with a mean age of 60.3 +/- 10.7 years were enrolled in this study. Preoperative and postoperative first day blood samples were collected to assess the IL-6 and hsCRP levels. IL-6 levels were measured by enzyme-linked immunosorbent assay, and hsCRP was measured by rate turbidimetry method. RESULTS: Fourteen patients (28.5%) developed AF postoperatively. Patients who developed AF showed elevated serum concentrations of postoperative first day IL-6 (P < .001), preoperative hsCRP (P < .005), and postoperative first day hsCRP (P < 0.001). Preoperative hsCRP levels (P < .002) and postoperative first day IL-6 (P < .001) and hsCRP (P < 0.001) levels were associated with prolonged endotracheal intubation time. Prolonged intensive care unit stay showed significant correlations with elevated levels of preoperative hsCRP (P < 0.002) and postoperative first day IL-6 (P < 0.001) and hsCRP (P < 0.001). There was also statistical significance between the AF+ and AF- groups regarding intensive care unit stay and endotracheal intubation times (P < .001 and P < .001, respectively). Cut-off points for postoperative first day IL-6, preoperative hsCRP, and postoperative first day hsCRP were 46.4 pg/mL (sensitivity = 92.9% and specificity = 80%), 0.46 mg/L (sensitivity = 71% and specificity = 75%), and 17.9 mg/L (sensitivity = 92.9% and specificity = 78%), respectively. CONCLUSIONS: Elevated IL-6 and hsCRP levels in patients with postoperative AF suggest inflammatory components have a role of in the pathogenesis of AF.