Significance of Coronary Artery Bypass Grafting–Associated Conduction Defects

The incidence of permanent atrioventricular conduction defects (CDs) caused by coronary artery bypass grafting (CABG) varies from 5% to 43% if cold crystalloid or blood cardioplegia is used for myocardial preservation. However, the long-term effects of CDs on clinical outcome are not well known. In this study we compared the outcome of 52 patients with permanent CABG-associated CDs (CD+) to 47 patients without CDs (CD−) after a 3-year follow-up. Recovery of CDs was found in 2 patients during the follow-up. There were no significant differences between groups in late mortality, cardiac or neurologic events, or capability to work. Although exercise capacity was similar, the exercise-limiting symptom more often was chest pain or dyspnea in the CD+ group than in the CD− group (p = 0.001). Left ventricular ejection fractions at rest and at 50-W workload level were lower in the CD+ group (p = 0.03 to 0.05). In addition, CD+ patients with left bundle branch block or cardiac pacemaker had significantly lower ejection fraction at maximal workload level than patients without CDs (p = 0.03). No significant differences were observed between the groups in the potential risk for ventricular arrhythmias according to signal-averaged electrocardiograms. In conclusion, the clinical outcome of patients with CDs after CABG operations is almost comparable to those without CDs during a 3-year follow-up. However, patients with CDs have lower left ventricular systolic function and more often have chest pain or dyspnea as the exercise-limiting symptom than patients without CDs.