CHA₂DS₂-VASc Score Calculator
Estimate stroke risk in non-valvular atrial fibrillation and see how the score compares with the guideline thresholds for oral anticoagulation.
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What the Score Estimates
The CHA₂DS₂-VASc score estimates the risk of stroke and systemic thromboembolism in people with non-valvular atrial fibrillation. It is one of the tools guidelines use to decide who should be offered oral anticoagulation. Each risk factor contributes points, and the total runs from 0 to 9.
- C — congestive heart failure or left ventricular dysfunction: 1
- H — hypertension: 1
- A₂ — age 75 or older: 2
- D — diabetes mellitus: 1
- S₂ — prior stroke, TIA or thromboembolism: 2
- V — vascular disease (previous myocardial infarction, peripheral artery disease, aortic plaque): 1
- A — age 65 to 74: 1
- Sc — female sex: 1
How the Thresholds Work
European guidelines treat the score differently in men and women, because female sex contributes a point on its own. In men, a score of 0 needs no anticoagulation, 1 is a judgement call, and 2 or more favours anticoagulation. In women, a score of 1 (sex alone) needs none, 2 is a judgement call, and 3 or more favours anticoagulation. Absolute annual stroke rates differ between study populations, so the score is best used as a threshold tool rather than as a precise risk percentage.
What Else Has to Be Weighed
Stroke risk is only half of the decision. Bleeding risk — commonly estimated with HAS-BLED — is the other, and modifiable factors such as uncontrolled blood pressure, alcohol use, and concurrent antiplatelet or NSAID use matter as much as the numbers. Where anticoagulation is indicated, most people without a mechanical valve or moderate-to-severe mitral stenosis are offered a direct oral anticoagulant rather than warfarin. Rate or rhythm control, and the underlying cause of the atrial fibrillation, are separate clinical decisions.
Limitations
- Validated for non-valvular atrial fibrillation. Mechanical heart valves and moderate-to-severe mitral stenosis require a different approach and are usually anticoagulated with warfarin.
- The score was derived in predominantly European cohorts; performance varies in other populations and in patients already taking antiplatelet drugs.
- It estimates risk, not treatment effect, and it does not account for time in therapeutic range, renal function, or patient preference.
- Risk scores support decisions — they do not make them. Do not start or stop any anticoagulant on the basis of a score alone.
Frequently Asked Questions
Does a high score mean I need anticoagulation?
It means guidelines would recommend discussing it. Whether to treat depends on bleeding risk, other medicines, kidney function, and your preferences — all of which need a clinician.
Why does the threshold differ for women?
Female sex scores 1 point by itself, but that point alone is not considered an indication for anticoagulation. The thresholds are therefore shifted by one point in women.
Is this score used for all types of atrial fibrillation?
No. It applies to non-valvular atrial fibrillation. People with a mechanical valve or moderate-to-severe mitral stenosis follow a different, warfarin-based pathway.