Stroke risk in non-valvular atrial fibrillation

What it is and when to use it

The CHA₂DS₂-VASc score estimates the annual risk of ischaemic stroke in patients with non-valvular atrial fibrillation and guides the decision to start oral anticoagulation. It adds points for congestive heart failure, hypertension, age, diabetes, prior stroke or TIA, vascular disease and female sex. It is the stroke risk score recommended by the 2024 ESC guidelines for the management of atrial fibrillation.

How to interpret it

A score of 0 in men, or 1 in a woman whose only point comes from being female, indicates low risk and oral anticoagulation is not recommended. A score of 1 in men or 2 in women lies in an intermediate band where anticoagulation should be considered (ESC Class IIa). From 2 points in men or 3 in women upward, oral anticoagulation is recommended (Class I). The estimated annual stroke risk rises from roughly 0.2% at a score of 0 to around 10% or more at the highest scores.

Limitations and when not to use it

CHA₂DS₂-VASc applies only to non-valvular atrial fibrillation. It should not be used in valvular AF (moderate-to-severe mitral stenosis or a mechanical heart valve), where anticoagulation is indicated regardless of the score. It estimates thrombotic risk only and does not assess bleeding risk, which is evaluated separately, for example with the HAS-BLED score. Female sex is a risk modifier rather than an independent indication: a woman with no other risk factors is managed like a man with a score of 0. The score informs but does not replace individualised clinical judgement.

Frequently asked questions

Which CHA₂DS₂-VASc score requires anticoagulation?

Oral anticoagulation is recommended from a score of 2 in men and 3 in women, and should be considered at 1 in men and 2 in women. A score of 0 in men, or 1 in a woman whose only point is her sex, does not warrant anticoagulation.

Does CHA₂DS₂-VASc measure bleeding risk?

No. It estimates stroke (thrombotic) risk only. Bleeding risk is assessed separately, for example with the HAS-BLED score, and the two are weighed together when deciding on anticoagulation.

Can it be used in valvular atrial fibrillation?

No. In valvular AF — moderate-to-severe mitral stenosis or a mechanical heart valve — anticoagulation is indicated regardless of the score, so CHA₂DS₂-VASc does not apply.