Background: Atrial fibrillation after cardiac operations is a source of morbidity and resource consumption. Various factors common to cardiac operations have been cited as causal. Comparison of the incidences of atrial fibrillation after conventional cardiac operations and minimally invasive cardiac operations may provide some insight into the mechanisms of this complication.
Methods: All patients undergoing minimally invasive direct coronary artery bypass grafting from January 26, 1996, through September 17, 1997, were evaluated for the occurrence of in-hospital postoperative atrial fibrillation. Data from these 55 patients were compared with data from a control cohort of patients undergoing conventional, solitary coronary artery bypass grafting. Each patient undergoing minimally invasive direct coronary artery bypass grafting was matched by age (+/- 3 years) and date of operation (+/- 7 days) with a patient undergoing conventional coronary artery bypass grafting.
Results: During the period since the advent of minimally invasive direct coronary artery bypass grafting at our institution, the incidence of postoperative atrial fibrillation has been slightly lower among the patients undergoing this form of coronary artery bypass grafting (26%) than among the total population of patients undergoing conventional coronary artery bypass grafting (34%). Comparison of the age-matched groups, however, showed the incidence to be slightly but not significantly greater in the minimally invasive direct coronary artery bypass grafting cohort (13/55, 24%) than in the conventional coronary artery bypass grafting cohort (11/55, 20%; P =. 6). The minimally invasive direct coronary artery bypass grafting group was less likely to be discharged with antiarrhythmic therapy than was the conventional coronary artery bypass grafting group (6 versus 10; P =.006).
Conclusions: According to these data, mechanisms traditionally implicated in atrial fibrillation after coronary artery bypass grafting, such as the use of cardiopulmonary bypass, mechanical manipulation of the atrium, and atrial ischemia, are not causal but may be related to the duration of the arrhythmic complication. Strategies directed toward management and reduction of the incidence of postoperative atrial fibrillation should be focused accordingly.