Postoperative atrial fibrillation in coronary artery bypass graft surgery occurs in 10 -40% of patients. It is associated with a significant degree of morbidity and results in prolonged lengths of stay in both the intensive care unit and hospital. Methods: The authors prospectively evaluated patients undergoing coronary artery bypass with detailed transesophageal echocardiography examinations conducted before and after cardiopulmonary bypass to study whether risk factors for atrial fibrillation

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... could be identified. Demographic and surgical parameters were also included in the analysis. Selected variables were subjected to univariate and subsequent multivariate analyses to test for their independent or joint influence on atrial fibrillation. Results: Seventy-nine patients had assessable transesophageal echocardiography examinations. Significant univariate predictors of atrial fibrillation included advanced age (P ‫؍‬ 0.002), pre-cardiopulmonary bypass left atrial appendage area (P ‫؍‬ 0.04), and post-cardiopulmonary bypass left upper pulmonary vein systole/diastole velocity ratio (P ‫؍‬ 0.03). When these three factors were considered together in a multiple logistic regression analysis, left upper pulmonary vein systole/diastole velocity ratio was a significant predictor (P < 0.05), as was the joint effect of age plus pre-cardiopulmonary bypass left atrial appendage area (P ‫؍‬ 0.005). The probability of developing atrial fibrillation for the combination of age ‫؍‬ 75 yr, post-cardiopulmonary bypass left upper pulmonary vein systole/diastole velocity ratio ‫؍‬ 0.5, and left atrial appendage area ‫؍‬ 4.0 cm was 0.83 (95% confidence interval, 0.51-0.96).