Fascicular conduction disturbances after coronary bypass surgery

Two hundred patients undergoing coronary bypass graft surgery were studied to determine the frequency and significance of new fascicular conduction disturbances. The follow-up period ranged from 13 to 39 months. New disturbances developed in 39 patients (20 percent). Isolated right bundle branch block (6 percent) and left anterior hemiblock (6 percent) were the most common disturbances. Right bundle branch block was usually transient and was not associated with further complications in the follow-up period. However, patients with either transient or persistent left bundle branch block or left anterior hemiblock, or both, had (1) increased late mortality compared with patients without new fascicular conduction disturbances (5 of 26 versus 11 of 161; P < 0.02), and (2) increased late myocardial infarction (2 of 26 versus 2 of 161; P < 0.05). New left fascicular conduction disturbances after coronary surgery identified a subset of patients with more extensive ischemic heart disease, suggesting that these patients require close follow-up care.