AF at intermediate stroke risk: a DOAC lowered the net clinical composite against no anticoagulation

Design

Multicentre, randomised, open-label, adjudicator-masked superiority trial

Population

1,803 patients with AF, CHA₂DS₂-VASc 1 (men) or 2 (women)

Primary outcome

Stroke, systemic embolism, major bleeding or CV 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-masked trial in South Korea. It randomised 1,803 patients with atrial fibrillation and intermediate stroke risk, a CHA₂DS₂-VASc score of 1 in men or 2 in women, to a DOAC or no anticoagulation. Mean age was 60; 24% were women.

At 24 months, the composite of stroke, systemic embolism, major bleeding or cardiovascular death occurred in 0.5% on a DOAC and 1.5% without (HR 0.31, 0.10 to 0.94). Stroke occurred in 0.3% against 1.1%. Major bleeding appeared similar and there were no cardiovascular deaths. Serious adverse events were 8.9% against 9.3%.

Guidelines have long recommended considering anticoagulation in this group without randomised evidence. This trial is the first to test it, and it favours treating. The absolute benefit is small, so the decision still rests on the patient's bleeding risk and preferences, but the default leans towards a DOAC.

• Calculate the stroke score at every AF diagnosis and review it annually
• Offer a DOAC to patients with a single non-sex risk factor after a bleeding-risk review
• Correct modifiable bleeding risks: blood pressure, alcohol, NSAIDs
• Record the patient's decision and the reasoning
• Use DOAC doses from the label, not reduced 'to be safe'

Why it matters

It gives trial evidence to a decision clinicians have been making on guideline opinion alone.

Don't overread it

With only 17 events, the estimate is imprecise, the trial was open-label, and it enrolled Korean patients with low bleeding rates.

The statistics, in plain English

The hazard ratio of 0.31 sounds dramatic, but there were only 4 against 13 events, so the interval runs from 0.10 to 0.94, barely excluding no effect. The absolute difference is 1 percentage point over two years, about 100 patients treated to prevent one event. A trial this small is most reliable for direction, less so for size.

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