Intermediate-risk atrial fibrillation: fewer strokes on a DOAC

Design

Multicentre, open-label, adjudicator-masked randomised superiority trial (SINGLE-AF)

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 0.10–0.94)

Guidelines give anticoagulation a class IIa recommendation for atrial fibrillation at intermediate stroke risk, but until now without trial evidence. SINGLE-AF, an open-label trial with masked outcome assessment, randomised 1,803 patients in South Korea with a CHA2DS2-VASc score of 1 in men or 2 in women to a DOAC or no anticoagulation. Mean age was 60.

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, 95% CI 0.10–0.94; absolute difference 1.0 percentage point). Strokes occurred in 3 versus 10 patients. Major bleeding appeared similar, and serious adverse events were 8.9% versus 9.3%.

For a neurologist seeing a younger patient after a cryptogenic event or with known paroxysmal atrial fibrillation and a single risk factor, this tips the balance towards anticoagulation. Event numbers were small, so the size of the benefit is uncertain, and the population was entirely East Asian.

• For atrial fibrillation with CHA2DS2-VASc 1 (men) or 2 (women), discuss starting a DOAC.
• Frame the benefit honestly: about one stroke-related event avoided per 100 patients over two years.
• Check bleeding risk and kidney function before starting.
• Use standard DOAC doses unless label criteria for reduction apply.
• Revisit the decision as age and risk factors change.

Why it matters

A recommendation built on observational data now has a randomised trial behind it.

Don't overread it

With 17 events in total, the precise size of the benefit is uncertain.

The statistics, in plain English

A hazard ratio of 0.31 means about two-thirds fewer events, but with only 17 events in total, the interval is wide (0.10 to 0.94): the true benefit could be large or modest. The absolute difference, one percentage point over two years, is what a patient experiences.

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