Sinus nodal function and risk for atrial fibrillation after coronary artery bypass graft surgery

Background Nonsurgical patients with sinus node dysfunction are at high ris k for atrial tachyarrhythmias, but whether a similar relation exists for at rial fibrillation after coronary artery bypass graft surgery is not clear. The purpose of this study was to evaluate sinus nodal function before and a fter coronary artery bypass graft surgery and to evaluate its relation with the risk for postoperative atrial arrhythmias. Methods: Sixty patients without complications having elective coronary arte ry bypass graft surgery underwent sinus nodal function testing by measureme nt of sinoatrial conduction time (SACT) and corrected sinus nodal recovery time (CSNRT), Patients were categorized based on whether postoperative atri al fibrillation developed. Results: Twenty patients developed atrial fibrillation between postoperativ e days 1 through 3, For patients remaining in sinus rhythm (n = 40), sinoat rial conduction times were no different and corrected sinus nodal recovery times were shorter after surgery when compared with measurements obtained a fter anesthesia induction, Sinus node function test results before surgery were similar between the sinus rhythm and the atrial fibrillation groups. A fter surgery, patients who later developed atrial fibrillation had longer s inoatrial conduction times compared with the sinus rhythm group (P = 0.006) , but corrected sinus nodal recover time was not different between these gr oups. A sinoatrial conduction time > 96 ms measured at this time point was associated with a 7.3-fold increased risk of postoperative atrial fibrillat ion (sensitivity, 62%; specificity, 81%; positive and negative predictive v alues, 56% and 85%, respectively; area under the receiver operator characte ristic curve, 0.72). Conclusions: These data show that sinus nodal function is not adversely aff ected by uncomplicated coronary artery bypass surgery. Patients who later d eveloped atrial fibrillation, however, had prolonged sinoatrial conduction immediately after surgery compared with patients remaining in sinus rhythm, These results suggest that injury to atrial conduction tissue at the time of surgery predisposes to postoperative atrial fibrillation and that assess ment of sinoatrial conduction times could provide a means of identifying pa tients at high risk for postoperative atrial fibrillation.