CHA2DS2-VASc Stroke Risk Calculator
The CHA2DS2-VASc score estimates the annual risk of stroke or thromboembolism in people with non-valvular atrial fibrillation (AFib). Answer the 8 clinical questions below and see your total score, the corresponding annual stroke risk percentage, and guidance on anticoagulation based on ESC and ACC/AHA guidelines. Results update instantly as you make selections.
What is the CHA2DS2-VASc score?
The CHA2DS2-VASc score is a clinical prediction rule used to estimate the annual risk of ischaemic stroke or systemic thromboembolism in patients with non-valvular atrial fibrillation (AFib). It was developed in 2010 by Lip et al. as a refinement of the earlier CHADS2 score, adding vascular disease, age 65-74, and sex category as additional risk factors to improve accuracy at the low-risk end of the spectrum. The acronym stands for: Congestive heart failure, Hypertension, Age >= 75 (2 points), Diabetes mellitus, prior Stroke/TIA/thromboembolism (2 points), Vascular disease, Age 65-74, and Sex category (female). The maximum possible score is 9.
How to calculate and interpret the score
Select your age group, sex, and answer yes or no to the six clinical conditions. Each yes adds 1 point, except prior stroke/TIA and age >= 75, which each add 2 points. The total score ranges from 0 to 9. A score of 0 in males (or 1 in females where the only point is from sex) indicates very low risk and anticoagulation is generally not recommended. A score of 1 in males represents a borderline group where anticoagulation may be considered after weighing individual risk factors. A score of 2 or higher in males (or 3 or higher in females) is where current ESC and ACC/AHA guidelines recommend oral anticoagulation, preferably with a direct oral anticoagulant (DOAC) such as apixaban, rivaroxaban, dabigatran, or edoxaban rather than aspirin, which is not effective for stroke prevention in AFib.
Female sex as a risk modifier, not a standalone risk factor
A common point of confusion is the role of female sex. The ESC 2020 guidelines emphasise that female sex is a "risk modifier" rather than an independent net risk factor. A woman with a score of 1 whose only point comes from being female is not considered to have a net increased stroke risk and does not need anticoagulation. However, a woman with a score of 2 or more - meaning at least one additional clinical risk factor - does qualify for anticoagulation. This is why the threshold for recommending anticoagulation in women is often described as a score >= 3 (or >= 2 with at least one non-sex risk factor). Always interpret the score in the clinical context of which factors are contributing.
Pairing with bleeding risk assessment
The CHA2DS2-VASc score addresses stroke risk but not bleeding risk. Before initiating anticoagulation, clinicians typically also calculate a bleeding risk score such as HAS-BLED (Hypertension, Abnormal renal/liver function, Stroke history, Bleeding history or predisposition, Labile INR, Elderly age > 65, Drugs/alcohol). A high HAS-BLED score does not automatically mean anticoagulation should be avoided, because the stroke risk in high CHA2DS2-VASc patients usually outweighs the bleeding risk, but it highlights modifiable bleeding risk factors (such as uncontrolled blood pressure or interacting medications) that should be addressed before or alongside anticoagulation. The decision to anticoagulate should always involve shared decision-making between clinician and patient.
Annual stroke risk by CHA2DS2-VASc score
| Score | Annual Stroke Risk | Risk Category | Anticoagulation Guidance |
|---|---|---|---|
| 0 | 0.2% | Very low (males) | No anticoagulation |
| 1 | 0.6% | Very low-low | No anticoagulation (females: score = sex only); consider if male |
| 2 | 2.2% | Low-moderate | Consider anticoagulation |
| 3 | 3.2% | Moderate | Recommend anticoagulation |
| 4 | 4.8% | Moderate | Recommend anticoagulation |
| 5 | 7.2% | High | Recommend anticoagulation |
| 6 | 9.7% | High | Recommend anticoagulation |
| 7 | 11.2% | High | Recommend anticoagulation |
| 8 | 10.8% | High | Recommend anticoagulation |
| 9 | 12.2% | High | Recommend anticoagulation |
Adjusted stroke rates from Lip et al. (2010) Chest and the Swedish Atrial Fibrillation Cohort (Friberg 2012). Risk increases substantially above a score of 4.
Frequently asked questions
What is the CHA2DS2-VASc score used for?
It is used to estimate the annual risk of stroke or systemic embolism in patients with non-valvular atrial fibrillation. Clinicians use it to decide whether anticoagulation therapy is appropriate. A higher score means greater stroke risk and a stronger case for starting an anticoagulant.
What score means anticoagulation is recommended?
Current ESC guidelines (2020) recommend anticoagulation for men with a score of 2 or higher, and for women with a score of 3 or higher (or 2 if the second point comes from a clinical risk factor rather than sex alone). The ACC/AHA guidelines similarly recommend anticoagulation at a score of 2 or above for most patients. A score of 1 in men is a grey zone where individual assessment and patient preference should guide the decision.
Why does prior stroke add 2 points?
A prior ischaemic stroke, TIA, or thromboembolism is the single strongest predictor of future stroke in patients with AFib. The doubled weight (2 points, represented as "S2" in the acronym) reflects the substantially elevated recurrence risk compared to other individual risk factors, and it is one of the two highest-weighted items in the score.
Why does being female add a point?
Studies found that female sex is associated with higher rates of AFib-related stroke in large population data. However, current guidelines treat it as a risk modifier rather than an independent net risk factor. Female sex at a score of 1 (sex is the only point) is generally not sufficient to recommend anticoagulation. The point matters most when combined with other clinical risk factors.
What is the difference between CHADS2 and CHA2DS2-VASc?
CHADS2 was the earlier 6-point score (max 6) that included Congestive heart failure, Hypertension, Age >= 75, Diabetes, and prior Stroke/TIA (2 points). CHA2DS2-VASc extended it by subdividing the age criterion, adding vascular disease, and adding female sex, pushing the maximum to 9. The expanded score better identifies patients who are truly at low risk - people who score 0 on CHA2DS2-VASc really do have a very low annual risk (around 0.2%) and can safely avoid anticoagulation.
Should I use aspirin instead of anticoagulation for a high score?
No. Current guidelines from ESC, ACC/AHA, and NICE explicitly recommend against using aspirin for stroke prevention in atrial fibrillation. Aspirin does not meaningfully reduce AFib-related embolic stroke and carries similar or higher bleeding risk compared to DOACs in older patients. DOACs such as apixaban or rivaroxaban are the preferred agents.