Discontinuing oral anticoagulation (OAC) therapy may result in a lower risk of a composite of stroke, systemic embolism or major bleeding versus continuing OAC therapy in patients who have undergone successful ablation for atrial fibrillation (AF) at least 12 months previously, as per results from a late-breaking trial presented yesterday at the European Society of Cardiology (ESC) congress (29 August–1 September, Madrid, Spain) and simultaneously published in the Journal of the American Medical Association.
OAC is recommended in all patients for at least two months after AF ablation in order to reduce the risk of stroke or thromboembolism. Thereafter, guidelines recommend continuing OAC, depending on the patient’s risk of stroke.
Explaining why the ALONE-AF trial was conducted, principal investigator Boyoung Joung (Yonsei University, Seoul, South Korea) said: “Many patients who have had a successful ablation and have stroke risk factors remain on OAC for the rest of their lives, although there is no evidence from randomised trials to indicate that this is necessary. We compared direct OAC therapy with no OAC therapy among patients one year after successful AF ablation who had at least one risk factor for stroke.”
ALONE-AF trial was an open-label randomised superiority trial conducted at 18 sites in South Korea. Eligible patients had non-valvular AF, had undergone their first catheter-based AF ablation, had no atrial arrhythmia recurrence for at least 12 months post-ablation, and had at least one stroke risk factor as determined by the CHA2DS2-VASc score (CHA2DS2-VASc ≥1 for males or ≥2 for females).
Patients were randomised 1:1 to receive direct OAC or no OAC therapy. Patients randomised to the OAC group received standard doses of apixaban, rivaroxaban or edoxaban, unless established dose-reduction criteria applied. The primary endpoint of net adverse clinical events was a composite of stroke, systemic embolism and major bleeding at 24 months. The study population included 840 randomised patients who had a mean age of 64 years, with 25% being women.
At 24 months, OAC was associated with a higher risk of net adverse clinical events than no OAC (2.2% vs 0.3%; absolute difference, −1.9%; 95% confidence interval [CI], −3.5 to −0.3; p=0.024).
No significant difference was observed in the incidence of ischaemic stroke or systemic embolism at 24 months between the OAC and no OAC groups (0.8% vs 0.3%, respectively; absolute difference, −0.5%; 95% CI, −1.6 to 0.6). Major bleeding occurred in 1.4% of patients in the OAC group and 0% in the no OAC group (absolute difference, –1.4%; 95% CI, −2.6 to −0.2).
“In the first randomised trial to address this question, receiving no OAC treatment resulted in a lower risk of harmful events than OAC treatment,” Joung stated. “A limitation was that the trial was not designed to detect a potential difference in ischaemic events, which occurred at a lower-than-expected rate. Our findings indicate that lifelong OAC might not be necessary in all patients who have had successful AF ablation at least one year previously.”
