Plate Nº 97 · recorded October 10, 2026
Health & Medicine ResearchReported finding
Blood thinners cut serious events 69% in intermediate-risk AF
The SINGLE-AF trial of 1,803 South Korean atrial fibrillation patients found direct oral anticoagulants cut serious events by 69% over two years, driven by fewer strokes, without increasing major bleeding.
By Elena Vasquez3 min read593 words
In brief
- SINGLE-AF cut serious cardiovascular events by 69% versus no anticoagulation in 1,803 AF patients over 24 months
- Composite event rate: 0.5% (DOAC) vs 1.5% (untreated); p=0.028; hazard ratio 0.31 (95% CI 0.10-0.94)
- Ischemic stroke: 0.1% (DOAC) vs 1.1% (untreated); major bleeding: 0.3% vs 0.5%, not statistically significant
- Presented September 27, 2026 at ESC Congress 2026 and published simultaneously in the New England Journal of Medicine
- Intermediate stroke risk defined as CHA2DS2-VASc score of 1 in men or 2 in women
Patients with atrial fibrillation at intermediate stroke risk had 69% fewer serious cardiovascular events when treated with newer blood thinners, a large randomized trial in South Korea has found. The benefit came without an increase in major bleeding, filling a long-standing gap in treatment guidance for this gray zone of patients.
The SINGLE-AF trial enrolled 1,803 adults at 18 medical centers in South Korea and tracked them for 24 months. Researchers presented the findings on September 27, 2026, during a Hot Line session at ESC Congress 2026, alongside simultaneous publication in the New England Journal of Medicine.
Who counts as "intermediate risk"?
Atrial fibrillation (AF) is a common heart rhythm disorder that raises the risk of blood clots and stroke. European Society of Cardiology guidelines strongly recommend oral anticoagulants for high-risk patients. For intermediate-risk patients, anticoagulants are only listed as something to "consider."
That ambiguity has fueled decades of debate. Older observational studies, particularly with vitamin K antagonists like warfarin, produced conflicting results in this group.
Trial principal investigator Professor Boyoung Joung of Yonsei University in Seoul explained the rationale. "Evidence from observational studies with anticoagulants, particularly vitamin K antagonists, remains conflicting in those at intermediate risk," he said. SINGLE-AF was designed to provide the first randomized evidence on whether DOACs benefit this patient group.
The trial defined intermediate risk as men with a CHA2DS2-VASc score of 1 and women with a score of 2. CHA2DS2-VASc is a standard clinical tool that estimates stroke risk from factors such as age, blood pressure, diabetes, and prior stroke.
How did the trial compare the treatments?
Researchers randomly assigned participants in a 1:1 ratio. One group received DOACs — apixaban 5 mg twice daily or rivaroxaban 20 mg once daily. The other group received no anticoagulation.
The study used an open-label design, so participants and clinicians knew who received which therapy.
What did the trial measure?
The primary endpoint combined stroke, systemic embolism, major bleeding, and cardiovascular death. Systemic embolism refers to a clot that travels through the bloodstream to lodge in a distant artery.
After 24 months, this composite occurred in 0.5% of DOAC patients and 1.5% of untreated patients. That difference translated to a 69% relative risk reduction (p=0.028; hazard ratio 0.31; 95% confidence interval 0.10 to 0.94). The benefit stemmed mostly from fewer ischemic strokes, which are clots blocking brain arteries.
Ischemic stroke struck 0.1% of DOAC patients versus 1.1% of untreated participants.
Did bleeding rates rise?
No, bleeding did not rise with treatment. Major bleeding occurred in 0.3% of DOAC patients and 0.5% of untreated patients, a difference that did not reach statistical significance.
Could the findings change guidelines?
Professor Joung said the trial provides the first randomized evidence for DOAC use in this patient group. "We now have evidence from a randomized trial that patients with AF at intermediate stroke risk benefit from DOAC therapy, without an increase in major bleeding," he said. He added the data may inform future guideline recommendations and reimbursement policies.
The study carries some limitations. As an open-label trial, it cannot fully rule out bias in event reporting. It enrolled patients only in South Korea. The absolute number of events was also small — 9 in the DOAC arm and 27 in the untreated arm — leaving confidence intervals wide.
Still, SINGLE-AF fills a critical evidence gap. For clinicians weighing anticoagulation in intermediate-risk AF patients, the trial now offers randomized data pointing clearly toward treatment.
via dx.doi.org (Original)