Ventricular conduction defects and atrial fibrillation after coronary artery bypass grafting. Multivariate analysis of preoperative, intraoperative and postoperative variables.

Preoperative, intraoperative and postoperative variables, which might play a role in the development of ventricular conduction defects (VCD) and atrial fibrillation (AF) following coronary artery bypass grafting (CABG), were evaluated in 236 consecutive patients. VCD and AF developed postoperatively in 15.5\% of patients: 4.5\% had VCD (subgroup A), 11.0\% had AF (subgroup B). In 84.5\% of patients VCD and AF did not occur (subgroup C). Univariate analysis showed statistically significant differences between subgroups A and C with respect to: left main significant stenoses and number of diseased vessels. Bypass pump time and aortic cross-clamp time were significantly longer in subgroup B. Multivariate analysis showed a significantly greater incidence of left main disease and of right coronary artery occlusion associated with significant stenosis of the proximal left anterior descending artery in subgroup A. In subgroup B, the duration of aortic cross-clamp time was significantly higher. Ischaemic injury, with increasing duration of cardioplegic arrest, seems to play a key role in the development of AF. Nonhomogeneous cardioplegic delivery to critical areas of myocardium, and particularly to the specialized conducting system, may cause VCD after CABG.