Oral anticoagulant use after catheter ablation for atrial fibrillation based on thrombo-embolic risk: future studies will be needed for bleeding high-risk group

This commentary refers to ‘Oral anticoagulation after atrial fibrillation catheter ablation: benefits and risks’, by K. Kanaoka et al., https://doi.org/10.1093/eurheartj/ehad798 and the discussion piece ‘What influences the bleeding risk of long-term anticoagulation after catheter ablation in patients with atrial fibrillation at high risk of thromboembolism?’, by L. Lv, https://doi.org/10.1093/eurheartj/ehae388. We thank Dr Lv for his insightful comments about our manuscript describing the benefits and risks of continuing oral anticoagulant (OAC) therapy after catheter ablation (CA) for atrial fibrillation (AF). First, Dr Lv commented on the inconsistent result of major bleeding between the CHADS2 score ≥ 3 and CHA2DS2-VASC score ≥ 4 groups. Although the both groups were considered as a high-risk group, the patient number and characteristics cannot be comparable between groups. In this study, the number of patients in the CHADS2 score ≥ 3 group was 20 227 and CHA2DS2-VASC ≥ 4 group was 38 704.1 The distribution based on CHADS2 and CHA2DS2-VASC score in this study was almost consistent with other Japanese registries.2 In this context, patients in the CHA2DS2-VASC ≥ 4 group included a relatively large number of patients from both the CHADS2 ≥ 3 and <3 groups, which may explain a higher bleeding risk when continuing OACs in the CHA2DS2-VASC ≥ 4 group. Although we used the CHADS2 score for the main analysis because the CHADS2 score showed good predictive performance in the Japanese population, the relatively small number of high risk (CHADS2 score ≥ 3) group may cause statistically negative results in the severe bleeding events in the continued OAC group. Thus, as mentioned in the Limitation section of our paper, future randomized controlled studies focusing on patients with higher thrombo-embolic risk patients would clarify these results. Second, Dr Lv suggested the use of the HAS-BLED score in the analysis of the bleeding risk. We agree that the HAS-BLED score is a more detailed and suitable risk assessment for bleeding. However, we commonly determine the continuation of OAC after CA based on thrombo-embolic scores for the prevention of thrombo-embolic events. Guidelines also have recommended the thrombo-embolic risk assessment for the continuation of OAC after catheter ablation (AHA/ESC guideline) as a first step;3,4 however, no large clinical trials and observational studies have been currently conducted. That is why we used a thrombo-embolic score for the risk stratification in our study. Although Dr Lv commented on patients with a higher risk of thrombo-embolic events, we stress importance of the risk stratification and benefits of discontinuation strategy of OAC in patients with a ‘lower’ thrombo-embolic risk, which included a large number of patients after CA. As we mentioned before, the number of patients with higher thrombo-embolic risk was relatively small, and several limitations may come from the observational nature of the study. Therefore, when future studies such as OCEAN and REACT-AF further clarify the benefits and risks for the continuation of OAC after CA in addition to our results,5 the bleeding risk assessment using HAS-BLED score will become useful along with thrombo-embolic risk assessment.