Burden Of Preoperative Atrial Fibrillation In Patients Undergoing Coronary Artery Bypass Grafting: An Analysis Of The Medicare-Linked Society of Thoracic Surgeons Database
S. Chris Malaisrie1, Patrick M McCarthy1, Jane Kruse2, Adin-Cristian Andrei3, Maria Grau-Sepulveda4, Daniel J Friedman5, James L Cox1, J. Matthew Brennan4
1Northwestern University Feinberg School of Medicine, Chicago, IL;2Northwestern Medicine, Chicago, IL;3Northwestern University, Chicago, IL;4Duke University, Durham, NC;5Duke Univeristy, Durham, NC
OBJECTIVES: Published reports on the association between preoperative atrial fibrillation (AF) and post-operative outcomes among patients undergoing coronary artery bypass grafting (CABG) have relied on single center, non-contemporary patient cohorts. This study compares early and late outcomes in patients with and without preoperative AF in a contemporary, nationally representative Medicare cohort. METHODS: In the Medicare-Linked Society of Thoracic Surgeons database, 361,138 patients underwent isolated CABG from 2006 to 2013, of whom 37,220 (10.3%) had preoperative AF; 13,161 (35.4%) were treated with concomitant surgical ablation and were excluded from the analysis. Generalized estimating equations were used to compare 30-day mortality and combined perioperative major morbidity between groups. Long-term survival was summarized using Kaplan-Meier curves and the log-rank test (unadjusted), and Cox regression models (adjusted). Stroke incidence was modeled using the Fine-Gray model for competing risks and the CHA2DS2-VASc score was used to analyze stroke risk. Median follow-up was 4 years (IQR 2-6 years).
Preoperative AF was associated with a higher adjusted 30-day mortality (odds ratio [OR] 1.5 (95% confidence interval [CI] 1.39-1.62), p<0.001) and combined major morbidity including stroke, renal failure, prolonged ventilation, reoperation, and mediastinitis (OR 1.32 (CI 1.27-1.37), p<0.0001). Likewise, patients with preoperative AF experienced a higher adjusted long-term risk of all-cause mortality (hazard ratio [HR] 1.45 (CI 1.41-1.48), p<0.001, figure) and stroke (HR 1.24 (CI 1.19-1.30), p<0.001) compared to those without preoperative AF. At five years, the survival probability in the preoperative AF group by CHA2DS2-VASc scores was 74.8% (score 1-3), 56.5% (score 4-6), and 41.2% (score 7-9) [p<0.001]; and the cumulative incidence of stroke was 7.9% (score 1-3), 12.2% (score 4-6), and 15.4% (score 7-9) [p<0.001].
Without concomitant AF ablation, preoperative AF is independently associated with worse early and late post-operative outcomes. The long-term risk of stroke and mortality increases with increasing CHA2DS2-VASc score. Further analyses of the comparative effectiveness of concomitant AF ablation and/or left atrial appendage interventions have important implications for this high-risk cohort.
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