Far and away, the most feared and devastating effect of Afib is stroke. The most common type of stroke is when part of the brain dies due to lack of blood flow, and this can occur in Afib because blood clots can form in the heart and travel to the brain.


Hi, I’m Dr. Hurst, we are going to discuss the role of blood thinners in Afib and answer the question, do you really need them?

Afib can increase your risk of stroke, and that risk is higher with an increasing number of risk factors for stroke. For example, two risk factors more than doubles the risk of stroke, and all eight risk factors increases the risk by over 12 times.

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Blood thinner risk assessment

Blood thinner medications decrease the risk of stroke by about 70% and the risk of death by about 25%, but of course at a slightly higher risk of bleeding.

The risk factors for stroke are:

  • Age over 65. An even higher risk for those over 75 years of age.
  • Having high blood pressure
  • Having a history of stroke, TIA, or mini-stroke. This is a particularly powerful predictor of stroke risk and counts double the other risk factors
  • Being female
  • Having a history of congestive heart failure
  • Having a history of vascular disease such as a heart attack, stent in your arteries, bypass surgery, or blockages in your peripheral arteries.
  • History of diabetes


Calculating stroke risk

To assess risk more clearly, doctors typically use a risk score called the CHA2DS2-VASc risk score. This risk score considers all of the above risk factors and is used to calculate an annual risk of stroke.

You can calculate your CHA2DS2-VASc risk score here: https://www.mdcalc.com/cha2ds2-vasc-score-atrial-fibrillation-stroke-risk

For example, if someone’s risk score is 2, they have a 2.2% chance of stroke per year if not taking blood thinners

Someone with all the risk factors, or a score of 9, would have a 12% risk of stroke.


How doctors decide if you should take a blood thinner

So, now you know how your risk for stroke is determined and what the CHA2DS2-VASc score is.

How do doctors use this information to decide if you should take a blood thinner or not? Although there may be other factors considered,

  • When the CHA2DS2-VASc is 0 in a man or 1 in a woman, most physicians do not recommend blood thinners.
  • When the CHA2DS2-VASc is two or more in a man or three or more in a woman, most physicians do recommend blood thinners if there is not a high risk of bleeding.
  • When the CHA2DS2-VASc is 1 in a man or 2 in a woman, this is controversial with some doctors recommending blood thinners, and others do not. This is an excellent opportunity for the physician and patient to have a shared decision-making conversation to see which approach makes the most sense.

Blood thinner medications decrease the risk of stroke by about 70% and the risk of death by about 25%, but of course at a slightly higher risk of bleeding.

If you have more questions about blood thinners for Afib, check out our other videos on which blood thinner is right for you and how do you know if your bleeding risk is too high.

And as always, I recommend talking to your doctor to understand better whether you need a blood thinner medication.

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