PROLONGED BRADYARRHYTHMIAS AFTER ISOLATED CORONARY-ARTERY BYPASS GRAFT-SURGERY

To evaluate clinical and electrocardiographic (ECG) characteristics th at may predict the occurrence of bradyarrhythmias after isolated coron ary artery bypass graft (CABG) surgery, 1614 consecutive patients who had this procedure performed at our institution from January 1988 to D ecember 1990 were reviewed. Thirteen (0.8%, 7 males and 6 females) pat ients had prolonged (mean 10.5 +/- 6.5 days) postoperative bradyarrhyt hmias and required insertion of a permanent pacemaker. Complete heart block occurred in eight patients and sinus node dysfunction in five. T hese 13 patients (group A) were compared with a group of 490 arbitrari ly selected CABG patients (group B) without bradyarrhythmias whose pre operative 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 l eft 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 degree s, p = 0.068) in group A patients. There were no differences between t he 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, mai nly complete heart block. Follow-up (mean 23.2 +/- 12.3 months) of pat ients demonstrates no or only partial recovery of atrioventricular con duction in patients with postoperative complete heart block (n = 8) an d persistent sinus node dysfunction in 3 of 5 patients with postoperat ive severe sinus arrest. Eleven of 13 patients continue to benefit fro m pacing. We conclude that a preoperative LBBB, age greater-than-or-eq ual-to 64 years, and concomitant LV aneurysmectomy are associated with a higher incidence of severe and prolonged postoperative bradyarrhyth mias after isolated coronary artery bypass graft surgery, and that the majority of patients continue to benefit from long-term pacing.