Risk of Thromboembolism Associated With Atrial Fibrillation Following Noncardiac Surgery

Background: The long-term risk of thromboembolism in patients developing new-onset post-operative atrial fibrillation (POAF) following noncardiac surgery is unknown, and data on stroke prophylaxis in this setting are lacking. Objectives: The purpose of this study was to assess the long-term risk of thromboembolism in patients developing new-onset POAF following noncardiac surgery relative to patients with nonsurgical, nonvalvular atrial fibrillation (NVAF). Methods: Using Danish nationwide registries, the authors identified all patients who developed POAF following noncardiac surgery from 1996 to 2015. These were matched by age, sex, heart failure, hypertension, diabetes, previous thromboembolism, ischemic heart disease, and year of diagnosis to patients with nonsurgical NVAF in a 1:4 ratio. Comparative long-term risk of thromboembolism was examined by multivariable Cox regression models. Results: In patients undergoing noncardiac surgery, 6,048 (0.4%) developed POAF during hospitalization, with the highest incidences following thoracic/pulmonary, vascular, and abdominal surgery. A total of 3,830 patients with POAF were matched with 15,320 patients with NVAF. Oral anticoagulation therapy was initiated within 30 days post-discharge in 24.3% and 41.3% of these patients, respectively (p value <0.001). The long-term risk of thromboembolism was similar in patients with POAF and NVAF (31.7 events vs. 29.9 events per 1,000 person years; hazard ratio [HR]: 0.95; 95% confidence interval [CI]: 0.85 to 1.07). Anticoagulation therapy during follow-up was associated with a comparably lowered risk of thromboembolic events in patients with POAF (HR: 0.52; 95% CI: 0.40 to 0.67) as well as NVAF (HR: 0.56; 95% CI: 0.51 to 0.62) compared with no anticoagulation therapy. Conclusions: New-onset POAF following noncardiac surgery was associated with a long-term risk of thromboembolism similar to NVAF.