AIM: To investigate the long-term risk of thromboembolism and serious bleeding associated with oral anticoagulation (OAC) therapy beyond 3 months after radiofrequency ablation (RFA) of atrial fibrillation (AF).

METHODS AND RESULTS: Linking Danish administrative registries, 4050 patients undergoing first-time RFA (2000-11) were identified. Risk of thromboembolism and serious bleeding according to OAC therapy were analysed by incidence rates (presented per 100 person-years) and Cox proportional-hazard models. The median age was 59.5 years (interquartile range, IQR: 52.8-65.2); 26.5% were females. During a median follow-up of 3.4 years (IQR: 2.0-5.6), 71 (1.8%) thromboembolism cases were identified, where incidence rates with and without OAC were 0.56 (0.40-0.78)95%CI and 0.64 (0.46-0.89)95%CI, respectively. Oral anticoagulation discontinuation remained insignificant [hazard ratio 1.42(0.86-2.35)95%CI] in multivariable analysis. Beyond 3 months after RFA 87 (2.1%) serious bleedings occurred; incidence rates with and without OAC were 0.99 (0.77-1.27)95%CI and 0.44 (0.29-0.65)95%CI, respectively. Oral anticoagulation therapy was significantly associated with serious bleeding risk [hazard ratio 2.05(1.25-3.35)95%CI]. In an age- and gender-matched cohort (1 : 4) of 15 848 non-ablated AF patients receiving rhythm-control therapy, thromboembolic rates with and without OAC were 1.34 (1.21-1.49)95%CI and 2.14 (1.98-2.30)95%CI, respectively. Adjusted incidence rate ratio was 0.53 (0.43-0.65)95%CI favouring RFA cohort.

CONCLUSION: Thromboembolic risk beyond 3 months after RFA was relatively low compared with a matched non-ablated AF cohort. With cautious interpretation due to low number of events, serious bleeding risk associated with OAC seems to outweigh the benefits of thromboembolic risk reduction. Randomized studies are warranted to test our results.