Altered expression of micro-RNA 195-199A and increased levels of cardiac SIRT1 protein are associated with the occurrence of atrial fibrillation after coronary artery bypass graft surgery

Background: Postoperative atrial fibrillation (POAF) is a potentially life-threatening complication after coronary artery bypass graft (CABG) surgery. The expression of the cardioprotective SIRT1 protein with its antioxidant activity is increased in cardiac tissue of patients suffering from POAF. So far, information is lacking about the relationship between SIRT1 regulating micro RNAs (miRNAs), SIRT1 protein and the occurence of POAF. Methods: A total of 63 patients undergoing CABG were recruited and biopsies were obtained from the right atrial appendage before aortic cross-clamping. Postoperative, all patients were rhythm-monitored until discharge and randomized to POAF (n=20) or sinus rhythm (n=43). The expression of the micro RNAs miRNA199a and miRNA195 was quantified by Real Time PCR. SIRT1 protein was detected by Westen Blot analysis. Results: The relative expression of miRNA199a in the POAF group was significantly decreased compared to the control group (0.7 ± 0.3 vs 1.2 ± 0.7; p = 0.02). MiRNA 199a was inversely correlated with the occurrence of POAF. There was no correlation between miRNA 195 and POAF. Accordingly, SIRT 1 protein was significantly induced in tissue probes of patients with POAF (p< 0.001). Conclusion: Altered expression of the SIRT1 protein regulating miRNA 199A in human atrial tissue was found to be related to the occurrence of POAF, indicating its usefulness as a biomarker for cardiac surgery management.