CHA2DS2-VASc Score Calculator

CHADS2 was the original 2001 Framingham-derived rule for stroke risk in nonvalvular atrial fibrillation and gave 1 point each for congestive heart failure, hypertension, age 75 or older, and diabetes, plus 2 points for prior stroke or TIA (maximum 6). The 2010 ESC refinement by Lip and colleagues added three modifiers that CHADS2 had missed: age 65 to 74 (1 point), vascular disease such as prior MI, peripheral artery disease, or aortic plaque (1 point), and sex category female (1 point), and also bumped age 75 or older from 1 to 2 points. The result is a 9-point scale that better separates truly low-risk patients (CHA2DS2-VASc 0) from low-but-not-zero risk patients, which matters because the threshold to start an oral anticoagulant is low.

The 2023 ACC/AHA/HRS atrial fibrillation guideline recommends oral anticoagulation when CHA2DS2-VASc is at or above 2 in men or at or above 3 in women. A direct oral anticoagulant (DOAC) such as apixaban, rivaroxaban, dabigatran, or edoxaban is preferred over warfarin in most patients, unless the patient has moderate-to-severe mitral stenosis or a mechanical heart valve, in which case warfarin remains the standard. For a score of 1 in a male patient, anticoagulation is reasonable (class IIa); for a score of 0, no antithrombotic therapy is recommended.

The original 2010 derivation showed that female sex was a risk modifier rather than an independent risk factor: in women with no other criteria, the absolute annual stroke rate is close to that of men with a score of 0, well under 1 percent. The 2023 ACC/AHA/HRS guideline, like the 2020 ESC update, therefore treats a score of 1 driven only by sex as not warranting anticoagulation. Once one additional risk factor is present, a female score of 2 is a shared-decision group where anticoagulation is reasonable but not automatic. A score of 3 or higher in women is the usual recommended-treatment threshold.

For atrial fibrillation without moderate-to-severe rheumatic mitral stenosis or a mechanical heart valve, current guidelines generally prefer a direct oral anticoagulant over warfarin. The specific choice and dose depend on kidney and liver function, age, weight, interactions, adherence, cost, and bleeding history. In end-stage kidney disease or dialysis, the 2023 ACC/AHA/HRS guideline says warfarin or an evidence-based dose of apixaban may be reasonable in selected patients. This decision requires a prescriber; the score cannot choose a drug.

HAS-BLED helps a clinician identify bleeding risks that may be modifiable, such as uncontrolled blood pressure, interacting drugs, alcohol use, or unstable INR on warfarin. A high score should prompt review and closer follow-up, not automatically deny anticoagulation. The balance between stroke prevention and bleeding is individualized, and this calculator does not make that decision.