Explainer
CHA2DS2-VASc, explained
If you have atrial fibrillation, your doctor has probably mentioned this score. Here is what it counts and how it shapes the blood thinner decision.
Why AFib needs its own score
In atrial fibrillation (AFib), the upper chambers of the heart beat irregularly, which lets clots form and travel to the brain. CDC lists irregular heartbeat among the heart conditions that raise stroke risk (CDC). Blood thinners lower that risk but add bleeding risk, so doctors need a way to weigh the two.
Where the score comes from
CHA2DS2-VASc was published in 2010 by Gregory Lip and colleagues, who refined an older score (CHADS2) and tested it in 1,084 people with AFib from the Euro Heart Survey (Lip 2010). People it classed as low risk had no clot-related events in that study (Lip 2010).
How it is counted
| Letter | Meaning | Points |
|---|---|---|
| C | Congestive heart failure | 1 |
| H | High blood pressure | 1 |
| A2 | Age 75 or older | 2 |
| D | Diabetes | 1 |
| S2 | Prior stroke, TIA or blood clot | 2 |
| V | Vascular disease (prior heart attack, peripheral artery disease, aortic plaque) | 1 |
| A | Age 65 to 74 | 1 |
| Sc | Sex category: female | 1 |
The maximum is 9 (Lip 2010).
What US guidelines do with it
The 2023 ACC/AHA/ACCP/HRS atrial fibrillation guideline recommends a blood thinner when the yearly stroke risk is about 2% or more, which it equates with a CHA2DS2-VASc of 2 or more in men and 3 or more in women (ACC/AHA 2023). At about 1% to 2% a year (a score of 1 in men or 2 in women), it calls for a shared decision (ACC/AHA 2023). The guideline also lets doctors use other risk tools and weigh bleeding risk (ACC/AHA 2023).
What does a score of 1, 2, 3, 4 or 5 mean?
The same number means slightly different things for men and women, because being female adds a point by itself. The table puts the guideline groups above side by side (ACC/AHA 2023).
| Score | Men | Women |
|---|---|---|
| 0 | Lowest-risk group | Not possible (the female point makes the minimum 1) |
| 1 | About 1% to 2% a year: shared decision about a blood thinner | Lowest-risk group (the point is for sex alone) |
| 2 | About 2% a year or more: blood thinner recommended | About 1% to 2% a year: shared decision |
| 3 | Blood thinner recommended | About 2% a year or more: blood thinner recommended |
| 4, 5 or higher | Blood thinner recommended | Blood thinner recommended |
In the 2010 study that introduced the score, the rate of strokes and other clot events went up as the score went up (Lip 2010). So a score of 5 does not just clear the line for treatment; it sits well above it. What a higher score does not change is the bleeding side of the decision, which the score does not measure.
How people reach each score
- A score of 2 can come from age 75 or older alone, from a prior stroke or TIA alone, or from two 1-point items, such as high blood pressure plus diabetes (Lip 2010).
- A score of 3 is common in a woman aged 65 to 74 with high blood pressure (1 for sex, 1 for age, 1 for blood pressure), or a man aged 75 or older with diabetes.
- A score of 4 or 5 usually means several items together, for example age 75 or older, high blood pressure and heart failure, with or without the point for sex.
Your own score is a starting point for a conversation with your clinician, who will also look at bleeding risk, kidney function and other medicines. This page does not tell anyone to start or stop a blood thinner.
Being female adds a point only alongside other risk factors; a woman with no other factors is still in the lowest-risk group (ACC/AHA 2023).
Limits
- Only for AFib that is not caused by certain heart valve problems.
- It does not estimate bleeding risk.
- It is not a stroke risk score for people without AFib. For them, see the stroke risk factor check.
Stroke signs: call 911. Balance loss, Eye changes, Face drooping, Arm weakness, Speech trouble: Time to call 911 (CDC).
Sources
- Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach. Chest. 2010;137(2):263-272. doi.org/10.1378/chest.09-1584
- Joglar JA, Chung MK, et al. 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation. J Am Coll Cardiol. 2024;83(1):109-279. doi.org/10.1016/j.jacc.2023.08.017
- Centers for Disease Control and Prevention. Stroke Risk Factors. www.cdc.gov/stroke/risk-factors/index.html
- Centers for Disease Control and Prevention. Signs and Symptoms of Stroke. www.cdc.gov/stroke/signs-symptoms/index.html
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-10-27. Spotted an error? See About.