Atrial Fibrillation Stroke Risk Calculator

The CHA₂DS₂-VASc Score Calculator estimates the annual statistical association with ischemic stroke for patients with non-valvular atrial fibrillation. This tool helps healthcare providers and patients assess clinical risk factors like age, hypertension, and prior stroke history. Whether you are evaluating a new screening assessment or reviewing current treatment plans, this calculator provides a standardized score to guide oral anticoagulation decisions.

Patient's age in years (18-120).
Biological sex assigned at birth.
History of heart failure or LV dysfunction.
History of high blood pressure or on medication.
Screening assessment of Type 1 or Type 2 diabetes.
History of ischemic stroke, TIA, or systemic embolism.
History of MI, peripheral artery disease, or aortic plaque.

How the CHA₂DS₂-VASc Score Is Calculated

The score is calculated by assigning points to specific risk factors known to contribute to stroke formation in patients with atrial fibrillation. The acronym stands for the factors assessed: Congestive heart failure, Hypertension, Age ≥75, Diabetes, Stroke, Vascular disease, Age 65–74, and Sex category.

Score = CHF + HTN + Age(≥75)×2 + DM + Stroke×2 + Vasc + Age(65–74) + Sex

Where:

  • CHF, HTN, DM, Vasc: 1 point each for presence of condition
  • Age ≥75: 2 points
  • Age 65–74: 1 point
  • Stroke/TIA: 2 points
  • Sex Category: 1 point for Female

Each factor adds to the cumulative risk because it represents a mechanism that promotes blood clot formation or disruption of normal blood flow. For example, hypertension damages blood vessel walls, making them prone to clots, while atrial fibrillation causes irregular heartbeats that can let clots escape the heart and travel to the brain.

What Your CHA₂DS₂-VASc Score Means

Your score translates directly into an estimated annual percentage statistical association with having a stroke. This number helps determine if the protective benefit of taking blood thinners (oral anticoagulation) outweighs the statistical association with bleeding complications.

Risk Interpretation Guidelines

Lower statistical association (Score 0 for men, 1 for women): The annual stroke risk is very low (<1-2%). Guidelines typically do not recommend anticoagulation therapy for these patients.

Intermediate Risk (Score 1 for men, 2 for women): There is a moderate risk. Physicians may consider anticoagulation based on individual patient preferences and other bleeding risk factors.

Higher statistical association (Score ≥2 for men, ≥3 for women): The stroke risk is significant enough that oral anticoagulation is strongly recommended to prevent life-threatening strokes.

Important: This calculator does not assess bleeding risk (e.g., using the HAS-BLED score). Starting anticoagulation is a decision that must balance stroke prevention against the statistical association with major bleeding.

Calculation logic verified using publicly available standards.

View our Accuracy & Reliability Framework →