Does preoperative atrial fibrillation increase the risk for mortality and morbidity after coronary artery bypass grafting?

Objectives: Preoperative atrial fibrillation has been associated with less favorable outcomes in patients undergoing coronary artery bypass grafting. However, it was never investigated in a large cohort of patients using a national database. This study aims to (1) identify the effect of atrial fibrillation on operative mortality and morbidity in patients undergoing isolated coronary artery bypass grafting and (2) identify the potential effect of atrial fibrillation on patients with decreased left ventricular ejection fraction (<= 40%). Methods: The Society of Thoracic Surgeons National Adult Cardiac Surgery Database was used for patients with coronary artery disease undergoing isolated coronary artery bypass grafting (n = 281,567). The association between atrial fibrillation and outcomes was estimated within 3 categories of low (ejection fraction, <40%), moderate (ejection fraction, 40%-55%), or normal (ejection fraction, >55%) systolic function. Results: Patients with atrial fibrillation were found to be older and have a higher incidence of comorbidities. A higher incidence of all major complications and mortality after surgical intervention was documented. An interaction between atrial fibrillation and an ejection fraction of greater than 40% for mortality, stroke, prolonged ventilation, and prolonged length of stay was identified. Conclusions: Our findings suggest that preoperative atrial fibrillation is associated with an increased risk for perioperative mortality and morbidity in patients undergoing coronary artery bypass grafting. The negative effect of atrial fibrillation might be more significant in patients undergoing coronary artery bypass grafting with an ejection fraction of greater than 40%. Both the EuroSCORE and, until recently, the Society of Thoracic Surgeons risk calculator do not include atrial fibrillation as a potential risk modifier; however, based on this study, it should be identified as a variable to be investigated and incorporated into future risk calculators.