PROLONGED BRADYARRHYTHMIAS AFTER ISOLATED CORONARY-ARTERY BYPASS GRAFT-SURGERY

To evaluate clinical and electrocardiographic (ECG) characteristics that may predict the occurrence of bradyarrhythmias after isolated coronary artery bypass graft (CABG) surgery, 1614 consecutive patients who had this procedure performed at our institution from January 1988 to December 1990 were reviewed. Thirteen (0.8%, 7 males and 6 females) patients had prolonged (mean 10.5 +/- 6.5 days) postoperative bradyarrhythmias and required insertion of a permanent pacemaker. Complete heart block occurred in eight patients and sinus node dysfunction in five. These 13 patients (group A) were compared with a group of 490 arbitrarily selected CABG patients (group B) without bradyarrhythmias whose preoperative ECGs were reviewed. Patients in group A were older (mean 69.2 vs 62.8 years; p = 0.0004) and had concomitant left ventricular (LV) aneurysmectomy more frequently (p = 0.02) and internal mammary graft revascularization less frequently (p = 0.022) than group 13 patients. Review of preoperative ECGs revealed a higher occurrence of complete left bundle branch block (LBBB) (5 of 13 vs 6 of 490; p < 0.0001) and a borderline, more leftward frontal plane QRS axis (-5.3 vs 13.1 degrees, p = 0.068) in group A patients. There were no differences between the groups with respect to gender, number of bypass grafts, location of prior myocardial infarction, and preoperative ECG intervals (PR, QRS, QTc). Multivariate analysis identified the presence of a preoperative LBBB, concomitant LV aneurysmectomy and age >64 years as independent predictors of severe and prolonged postoperative bradyarrhythmias, mainly complete heart block. Follow-up (mean 23.2 +/- 12.3 months) of patients demonstrates no or only partial recovery of atrioventricular conduction in patients with postoperative complete heart block (n = 8) and persistent sinus node dysfunction in 3 of 5 patients with postoperative severe sinus arrest. Eleven of 13 patients continue to benefit from pacing. We conclude that a preoperative LBBB, age greater-than-or-equal-to 64 years, and concomitant LV aneurysmectomy are associated with a higher incidence of severe and prolonged postoperative bradyarrhythmias after isolated coronary artery bypass graft surgery, and that the majority of patients continue to benefit from long-term pacing.