Impaired myocardium energetics associated with the risk for new-onset atrial fibrillation after isolated coronary artery bypass graft surgery

BACKGROUND: New-onset postoperative atrial fibrillation (POAF) is one of the most common complications occurring in 10-40% of patients after coronary artery bypass graft (CABG) surgery. Recent studies suggest that dysmetabolism may contribute to the pathogenesis of atrial fibrillation; however, the putative mechanism in patients undergoing CABG surgery is unknown. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) has been demonstrated as a master regulator of myocardial energy metabolism, and glucose transporter 3 (GLUT3) has both a higher affinity for glucose and a much greater transport capacity compared with GLUT1, GLUT2, and GLUT4. We sought to evaluate the role of energy metabolism, especially the glucose metabolism, on patients after isolated CABG surgery. METHODS AND RESULTS: Right atrial appendages were obtained from 79 patients who were in normal sinus rhythm and undergoing isolated CABG; those who exhibited new-onset POAF (n=22) or remained in sinus rhythm (n=57) were prospectively matched on the basis of preoperative, intraoperative, and postoperative characteristics. POAF was assessed by electrocardiogram and must have required the initiation of antiarrhythmic therapy or anticoagulation. Local PGC-1α and GLUT3 concentrations were quantified by enzyme-linked immunosorbent assay in tissue homogenates. The comparison of mRNA expression was tested by quantitative real-time PCR. PGC-1α and GLUT3 levels and the related protein mRNA expression were significantly reduced in POAF patients compared with controls (P<0.05). This selective reduction in PGC-1α was associated with the presence of diabetes mellitus (P<0.05). CONCLUSION: Patients who have low PGC-1α and GLUT3 levels are at increased risk for new-onset POAF. The myofibrillar energetic impairment may be important in the pathogenesis of atrial fibrillation.