- Design
- Open-label, adjudicator-masked, randomised superiority trial
- Population
- 1,803 Korean patients with AF and CHA2DS2-VASc 1 (men) or 2 (women)
- Primary outcome
- Stroke, systemic embolism, major bleeding or cardiovascular death at 24 months
- Effect
- 0.5% vs 1.5%; HR 0.31 (95% CI 0.10 to 0.94)
SINGLE-AF was an open-label, adjudicator-blinded randomised trial in South Korea. It enrolled 1,803 patients with atrial fibrillation and a CHA2DS2-VASc score of 1 in men or 2 in women, mean age 60, and assigned them to a direct oral anticoagulant or no anticoagulation.
At 24 months the composite of stroke, systemic embolism, major bleeding or cardiovascular death occurred in 0.5% on anticoagulation and 1.5% without (difference -1.0 percentage point, 95% CI -2.0 to -0.1; hazard ratio 0.31, 0.10 to 0.94). Strokes were 3 against 10. Major bleeding and serious adverse events were similar, and there were no cardiovascular deaths.
US and European guidelines already give anticoagulation a class IIa recommendation for this group; this is the first randomised support for it. But the absolute benefit is small, with about 100 patients treated for two years to prevent one event, and the numbers behind it are few. For neurologists seeing a patient after a cryptogenic event or with incidental AF, it strengthens the case for anticoagulation when the score is intermediate, alongside the patient's own bleeding risk and preferences. Guidelines have not changed on the strength of this trial.
- For atrial fibrillation with a CHA2DS2-VASc of 1 (men) or 2 (women), consider offering a DOAC.
- Assess bleeding risk before starting, and correct modifiable factors such as uncontrolled hypertension.
- About 100 patients would need two years of treatment to prevent one composite event.
- Discuss the small absolute benefit openly; patient preference is a legitimate deciding factor.
- These were Korean patients with a mean age of 60; results may differ in other populations.
Why it matters
It turns a guideline recommendation built on observational data into one with randomised support, for a group neurologists often see after a first event.
Don't overread it
With only 17 primary events, the size of benefit is uncertain, and the trial was open-label.
The statistics, in plain English
The hazard ratio of 0.31 sounds dramatic, but its confidence interval runs from 0.10 to 0.94, so the true reduction could be large or modest. The absolute difference, 1 percentage point over two years, is the figure to use when discussing treatment with a patient.
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