Free CHA₂DS₂-VASc / CHA₂DS₂-VA Stroke Risk Calculator (2026)

Consider an 80-year-old woman with a history of an ischemic stroke two years ago, and no other documented risk factors — no heart failure, no hypertension, no diabetes, and no known vascular disease. Working through the classic CHA₂DS₂-VASc criteria: her age of 80 falls in the ≥75 band, contributing 2 points; her prior stroke contributes 2 points, since stroke/TIA/thromboembolism is double-weighted in this score; and her sex contributes 1 point under the classic convention. Heart failure, hypertension, diabetes, and vascular disease are all absent, contributing nothing.

That totals CHA₂DS₂-VASc = 2 + 2 + 1 = 5. Dropping the sex criterion, her CHA₂DS₂-VA = 4. Both numbers sit far above the threshold at which guidelines recommend anticoagulation rather than merely considering it — in this patient, the prior stroke alone would already justify anticoagulation regardless of the rest of the profile, and the score simply confirms and quantifies that. Enter age 80, sex female, and check only “prior stroke, TIA, or thromboembolism” in the calculator above to reproduce this result.

Stroke risk was estimated using the CHA₂DS₂-VASc score (1 point each for congestive heart failure/LV dysfunction, hypertension, diabetes mellitus, vascular disease, and female sex; 1 point for age 65–74 or 2 points for age ≥75; 2 points for prior stroke, transient ischemic attack, or thromboembolism; maximum 9 points) as derived by Lip et al. in the Euro Heart Survey cohort, with the sex-free CHA₂DS₂-VA variant (maximum 8 points) reported in parallel per the 2024 ESC atrial fibrillation guideline (Lip et al., Chest. 2010;137(2):263–272; Van Gelder et al., Eur Heart J. 2024;45(36):3314–3414).

This score applies to non-valvular atrial fibrillation only. It should not be applied to, and does not determine anticoagulation need in, patients with a mechanical heart valve or moderate-to-severe mitral stenosis — those patients require anticoagulation on the basis of the valve lesion itself, independent of their calculated score, and are excluded from the populations these criteria were derived and validated in.

The score also assumes the diagnosis of atrial fibrillation (or atrial flutter) is already established; it is not a diagnostic tool for arrhythmia. It estimates annual stroke risk to inform the anticoagulation decision — not which specific anticoagulant to use, what dose, or how to manage a patient already stable on treatment. Finally, it is one input into a decision that should also weigh bleeding risk (see HAS-BLED) and patient preference — a calculated score is a starting point for that conversation, not its conclusion.