Abstract 12488: Oral Anticoagulation for New Onset Post-Operative Atrial Fibrillation After Combined Coronary Artery Bypass Grafting and Valve Surgery is Not Associated With Improved Outcomes

Abstract

Introduction: Post-operative atrial fibrillation (POAF) after cardiac surgery is common and is associated with increased risk of stroke and death. The incidence of POAF is highest among patients who undergo combined CABG and valve surgery, at 40-60%. The risks and benefits of oral anticoagulation (OAC) in this high-risk population are not well established. Research Question: Among patients with POAF after combined CABG and valve surgery, what is the association between OAC use and clinical outcomes? Methods: From a population-based registry in Ontario, Canada, we identified consecutive patients >65 years of age who developed POAF after combined CABG and left-sided, non-mechanical valve surgery from Oct/08-Mar/18. The exposure of interest was OAC prescription within 90 days after hospital discharge. Outcomes included death, cardiovascular death, stroke, MI, thromboembolism, and bleeding. Follow-up began at 90 days after discharge and continued for 24 months. Outcomes were analyzed using inverse probability of treatment weighting using the propensity score. Statistical measures of association were reported as hazard ratios with 95% confidence intervals. Results: Among 4,836 patients who had combined CABG/valve surgery, 1,939 (40.1%) developed POAF and these patients had a higher rate of death (HR 1.31, 95% CI 1.01-1.68 P=0.04). OAC was prescribed in 1,153 (59.5%) patients (86% warfarin and 14% DOAC). The use of OAC was not associated with a lower rate of death, stroke/MI/thromboembolism, or cardiovascular death but was associated with an increased rate of bleeding (HR 1.62, 95% CI 1.00-2.61, P=0.048). Conclusion: Among patients with POAF after combined CABG/valve surgery, use of warfarin or DOAC did not improve ischemic cardiovascular outcomes or survival and was associated with higher rates of bleeding. Randomized control trials are needed to define the risk and benefit of OAC use in this high-risk population. Until then, routine use of OAC is not recommended.