Burden of preoperative atrial fibrillation in patients undergoing coronary artery bypass grafting.

Abstract

This study compares early and late outcomes in patients undergoing coronary artery bypass grafting with and without preoperative atrial fibrillation in a contemporary, nationally representative Medicare cohort. In the Medicare-Linked Society of Thoracic Surgeons database, 361,138 patients underwent isolated coronary artery bypass from 2006 to 2013, of whom 37,220 (10.3%) had preoperative atrial fibrillation; 13,161 (35.4%) were treated with surgical ablation and were excluded. Generalized estimating equations were used to compare 30-day mortality and morbidity. Long-term survival was summarized using Kaplan-Meier curves and Cox regression models. Stroke and systemic embolism incidence was modeled using the Fine-Gray model and the CHA₂DS₂-VASc score was used to analyze stroke risk. Median follow-up was 4 years. Preoperative atrial fibrillation was associated with a higher adjusted in-hospital mortality (odds ratio [OR], 1.5; P < .0001) and combined major morbidity including stroke, renal failure, prolonged ventilation, reoperation, and deep sternal wound infection (OR, 1.32; P < .0001). Patients with preoperative atrial fibrillation experienced a higher adjusted long-term risk of all-cause mortality and cumulative risk of stroke and systemic embolism compared to those without atrial fibrillation. At 5 years, the survival probability in the preoperative atrial fibrillation versus no atrial fibrillation groups stratified by CHA₂DS₂-VASc scores was 74.8% versus 86.3% (score 1-3), 56.5% versus 73.2% (score 4-6), and 41.2% versus 57.2% (score 7-9; all P < .001). Preoperative atrial fibrillation is independently associated with worse early and late postoperative outcomes. CHA₂DS₂-VASc stratifies risk, even in those without preoperative atrial fibrillation.