Annual stroke risk for non-valvular atrial fibrillation.
Source: Lip et al., Chest 2010.
What does the CHA₂DS₂-VASc score mean?
The CHA₂DS₂-VASc score is a clinical prediction rule used to estimate the annual risk of stroke in patients with non-valvular atrial fibrillation (AF), an irregular heart rhythm that promotes clot formation in the left atrial appendage. These clots can travel to the brain and cause embolic stroke.
The score was published by Lip and colleagues in 2010 as a refinement of the older CHADS₂ score, expanding it to include vascular disease, age 65–74 years, and female sex as additional risk modifiers. It ranges from 0 to 9, with each point corresponding to a clinical risk factor.
The acronym encodes the variables: Congestive heart failure (1), Hypertension (1), Age ≥ 75 (2 points, hence A₂), Diabetes (1), prior Stroke/TIA (2 points, S₂), Vascular disease (1), Age 65–74 (1), female Sex category (1). The maximum score is 9.
The score guides anticoagulation decisions. In patients with AF, oral anticoagulants (warfarin or direct oral anticoagulants) significantly reduce stroke risk but carry a bleeding risk. The CHA₂DS₂-VASc score helps clinicians identify patients whose stroke risk is high enough to justify anticoagulation therapy. Most guidelines recommend anticoagulation for men with score ≥ 2 and women with score ≥ 3.
Reference ranges (annual stroke risk)
| Score | Approx. annual stroke risk | Anticoagulation guidance |
|---|---|---|
| 0 (men) / 1 (women, female sex only) | ~0% | No anticoagulation recommended |
| 1 (men) | ~1.3% | Consider anticoagulation |
| 2 | ~2.2% | Anticoagulation generally recommended |
| 3 | ~3.2% | Anticoagulation recommended |
| 4–5 | ~4–7% | Anticoagulation strongly recommended |
| ≥ 6 | ~10–15% | Anticoagulation essential |
When should you see a doctor?
Any person with known or suspected atrial fibrillation should be under regular medical care. The CHA₂DS₂-VASc score is a tool to inform, not replace, clinical judgement. Anticoagulation decisions must account for bleeding risk (assessed with scores like HAS-BLED), patient preferences, renal function, and drug interactions. Do not start or stop anticoagulation based on this calculator alone.