CHA₂DS₂-VASc Calculator

CHA₂DS₂-VASc scoring

Each present risk factor adds its points to the total, which ranges from 0 to 9. Age contributes under either the A₂ item (75 or over) or the A item (65–74) — never both.

Scoring follows the Euro Heart Survey derivation by Lip et al. (Chest 2010), the scheme adopted by NICE NG196.

CHA₂DS₂-VASc score interpretation

Thresholds follow NICE NG196. Anticoagulation choices always sit alongside a formal bleeding risk assessment and shared decision making.

• 0 (or 1 in a woman whose only factor is her sex)Very low risk

  Do not offer stroke prevention with anticoagulation on the basis of this score. Review when the patient reaches 65 or if diabetes, heart failure, vascular disease or prior stroke develops.

• 1 (man)Intermediate risk

  Consider anticoagulation with a direct-acting oral anticoagulant, taking into account the risk of bleeding.

• 2 or aboveIncreased risk

  Offer anticoagulation with a direct-acting oral anticoagulant, taking into account the risk of bleeding. Assess bleeding risk before starting and review at least annually.

NICE NG196 recommends assessing bleeding risk with the ORBIT score when considering or reviewing anticoagulation. Aspirin monotherapy is not offered for stroke prevention in atrial fibrillation.

How to calculate CHA₂DS₂-VASc

1. 1Confirm the indication: symptomatic or asymptomatic paroxysmal, persistent or permanent atrial fibrillation, atrial flutter, or continuing arrhythmia recurrence risk after cardioversion or ablation.
2. 2Record each clinical risk factor — heart failure, hypertension, diabetes, previous stroke, TIA or thromboembolism, and vascular disease.
3. 3Assign the single applicable age item: 0 under 65, 1 point for 65–74, or 2 points for 75 or older.
4. 4Add 1 point if the patient is female.
5. 5Apply the NICE NG196 thresholds above, assess bleeding risk, and discuss the balance of benefits and risks with the patient.

Common pitfalls

• Skipping the bleeding risk assessment. NG196 pairs the CHA₂DS₂-VASc score with the ORBIT score — a high predicted stroke risk is not by itself a reason to skip that step, and bleeding risk is not a simple cut-off for refusing treatment.
• Counting age twice. The A₂ and A items are alternatives: a patient aged 76 scores 2 for age, not 3.
• Treating female sex as a stand-alone reason to treat. Sex category modifies risk; in isolation it does not trigger anticoagulation.
• Withholding anticoagulation solely because of age or falls risk. NG196 states neither should be the sole reason.
• Offering aspirin instead of anticoagulation. Aspirin monotherapy is not recommended for stroke prevention in atrial fibrillation.
• Forgetting valve status. Where DOACs are contraindicated, not tolerated or unsuitable, NICE recommends a vitamin K antagonist — and some valve situations change the anticoagulation strategy entirely.

Frequently asked questions

What CHA₂DS₂-VASc score means anticoagulation?

NICE NG196 recommends offering anticoagulation with a direct-acting oral anticoagulant at a score of 2 or above, taking bleeding risk into account. For men with a score of 1, anticoagulation is considered. Women whose only risk factor is their sex category (a score of 1) are not offered anticoagulation on the basis of the score.

How is CHA₂DS₂-VASc different from CHADS₂?

CHADS₂ scored five items (heart failure, hypertension, age 75 or over, diabetes, prior stroke or TIA) to a maximum of 6. CHA₂DS₂-VASc refined it by adding age 65–74, vascular disease and female sex, improving identification of patients who are genuinely at very low risk.

Why does female sex add a point?

Female sex modestly increases stroke risk in people who already have at least one other risk factor, but on its own it does not make anticoagulation worthwhile. That is why the sex point only matters once another factor is present.

Does CHA₂DS₂-VASc apply to atrial flutter?

Yes. NICE NG196 recommends using the score for people with atrial flutter, and for those at continuing risk of arrhythmia recurrence after cardioversion or catheter ablation, as well as for atrial fibrillation.

How often should the score be reassessed?

Risk changes with age and new diagnoses. NICE advises reviewing stroke risk annually for people already taking an anticoagulant, and for people not taking one, when they reach 65 or develop diabetes, heart failure, peripheral arterial disease, coronary heart disease or a history of stroke, TIA or systemic thromboembolism.

Sources and further reading

• Atrial fibrillation: diagnosis and management (NG196) — NICE
• Lip GYH et al. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the Euro Heart Survey on atrial fibrillation. Chest 2010;137(2):263–72 — PubMed

This page is reference information for registered healthcare professionals. It is not medical advice and does not replace clinical judgement, local policy, or the current version of the source guidance. Always verify scores and thresholds against your own organisation's pathway before acting on them.