Patients with atrial fibrillation at intermediate risk of stroke can safely benefit from direct oral anticoagulant therapy without facing increased major bleeding risks, according to landmark findings from the SINGLE-AF trial presented at the ESC Congress 2026 and published simultaneously in the New England Journal of Medicine.
For years, clinicians navigating stroke prevention for patients with atrial fibrillation have faced a distinct clinical grey area. While current guidelines firmly recommend oral anticoagulants for patients with AF at high risk of stroke, evidence supporting the use of these medications in patients with intermediate risk has remained sparse and often contradictory. To address this persistent gap, researchers conducted the SINGLE-AF trial, designed to provide the first rigorous randomized data on whether newer pharmaceutical blood thinners offer real clinical advantages to this intermediate-risk population.
Trial Design and Findings from the SINGLE-AF Study
Led by Principal Investigator Professor Boyoung Joung from Yonsei University in Seoul, South Korea, the open-label trial enrolled 1,803 individuals diagnosed with atrial fibrillation who carried an intermediate risk of stroke. Researchers defined this intermediate tier as a CHA2DS2-VASc score of 1 in men or 2 in women. Participants across 18 clinical centers in South Korea were randomized on a one-to-one basis to receive either direct oral anticoagulant therapy—consisting of apixaban 5 mg twice daily or rivaroxaban 20 mg once daily—or no anticoagulation therapy at all.
At the 24-month mark, the results revealed a striking 69% reduction in the trial’s primary endpoint, which measured a composite of stroke, systemic embolism, major bleeding, or cardiovascular death. Investigators observed these adverse events in just 0.5% of the DOAC-treated group compared with 1.5% in the untreated group. This statistical difference, accompanied by a hazard ratio of 0.31, pointed directly to a lower incidence of ischaemic stroke with DOAC therapy at 0.1% versus 1.1% in the control arm. Crucially, this protective benefit came without a statistical penalty in bleeding complications, as major bleeding occurred in 0.3% of patients on DOACs and 0.5% of those without.
“We now have evidence from a randomised trial that patients with AF at intermediate stroke risk benefit from DOAC therapy, without an increase in major bleeding. Data from the SINGLE-AF trial may be used to inform future guideline recommendations and reimbursement policies.”
Professor Boyoung Joung, Principal Investigator of the SINGLE-AF trial
Reevaluating Post-Ablation Therapy Through the OCEAN Trial
While the SINGLE-AF trial validates treatment in intermediate-risk cohorts, another major international study has upended long-held assumptions regarding patients who undergo procedural intervention. Historically, individuals undergoing catheter ablation to restore a normal heart rhythm were advised to continue life-long blood thinners regardless of procedure success, largely because physicians lacked definitive proof that eliminating the arrhythmia sufficiently suppressed long-term stroke danger.
The Optimal Anticoagulation for Enhanced Risk Patients Post-Catheter Ablation for Atrial Fibrillation trial challenged this standard practice. Co-led by Dr. David Birnie at the Ottawa Heart Institute and Dr. Atul Verma at the McGill University Health Centre, the study followed 1,284 patients across international sites over a three-year window. Researchers evaluated whether continuing potent anticoagulants offered any added protection compared with low-dose aspirin after a successful ablation procedure.
The findings demonstrated that one year after a successful ablation, the underlying stroke risk drops so substantially that the bleeding hazards of continuing long-term anticoagulation outweigh any marginal benefit. Patients taking rivaroxaban experienced clinically relevant, non-major bleeding—defined as bleeding severe enough to require medical attention—at a rate of 5.5%, compared to just 1.6% among those assigned to aspirin. By contrast, stroke rates between the rivaroxaban and aspirin arms showed no significant clinical variance.
Future Clinical Guidance and Policy Implications
Together, these distinct clinical trials illustrate a shifting paradigm in modern cardiology: tailoring antithrombotic therapy precisely to the patient’s current disease burden and procedural outcome rather than applying blanket lifelong prescriptions. Where unmanaged intermediate-risk patients find a clear defensive advantage in direct oral anticoagulants, patients who achieve procedural success via catheter ablation may find a safer path off heavy thinners entirely.
As health systems digest these published data from the New England Journal of Medicine, cardiology specialists anticipate that both the SINGLE-AF and OCEAN trials will directly shape forthcoming cardiovascular guidelines and global reimbursement frameworks, ultimately refining how physicians balance stroke prevention against the tangible risks of hemorrhage.
