Scores & indices
CHA₂DS₂-VASc calculator
Eight bedside factors, one anticoagulation decision — with the annual stroke risk drawn as 100 people with AF.
How to read the result
CHA₂DS₂-VASc falls into these published bands.
A 79-year-old man in atrial fibrillation with hypertension and a history of heart failure.
CHA₂DS₂-VASc 4 — elevated risk (~4% annual stroke risk)
Well past the anticoagulation threshold: offer an oral anticoagulant unless contraindicated, and use HAS-BLED to find modifiable bleeding factors rather than as a reason to withhold.
Who this is for
For clinicians deciding whether a patient with non-valvular atrial fibrillation needs oral anticoagulation. Each risk factor is a tap; the total maps to the adjusted annual stroke rate from the Lip 2010 validation cohort and the ESC thresholds — offer anticoagulation at ≥ 2 in men or ≥ 3 in women, with female sex counting only in the presence of other risk factors.
How it works
What it calculates
Annual stroke risk in non-valvular atrial fibrillation, guiding the anticoagulation decision.
Interpreting the result
Score 0 in men (or 1 in women from sex alone): no anticoagulation. Score 1 in men: consider it. Score ≥ 2 in men or ≥ 3 in women: offer oral anticoagulation unless contraindicated. Female sex only adds risk in the presence of other factors.
The other half of the decision
Bleeding risk (HAS-BLED or similar) identifies modifiable risk factors to correct — it is rarely a reason to withhold anticoagulation in a patient with a clear indication.
Built on published evidence
- ESC AF guidelines; validation: Lip et al. 2010
Codification last reviewed 2026-08-28, and checked against published reference values in automated tests on every release — see the full evidence ledger.
Questions clinicians ask
Does a score of 1 need anticoagulation?
It depends on where the point comes from. A score of 1 in a man means anticoagulation should be considered (ESC AF guidelines); a score of 1 in a woman from sex alone does not — female sex modifies risk only in the presence of other risk factors.
Can I use it in valvular AF?
No — the score applies to non-valvular AF only. Mechanical heart valves and mitral stenosis carry an indication for anticoagulation regardless of the score, so there is no decision for CHA₂DS₂-VASc to make.
Should a high HAS-BLED score stop me anticoagulating?
Rarely. Bleeding-risk scores exist to surface modifiable factors — blood pressure control, INR stability, antiplatelets, alcohol — and to schedule closer review. In most patients with a clear stroke-prevention indication, the ischaemic risk of withholding exceeds the bleeding risk of treating.
Where do the stroke percentages come from?
Adjusted annual stroke rates from the Lip 2010 validation cohort. At scores 7–9 the rates come from small cohort cells and are non-monotonic — a quirk of the data, not of biology, and the tool says so.
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