Atrial Fibrillation and Stroke Prevention

Authored by , Reviewed by Dr Adrian Bonsall | Last edited | Certified by The Information Standard

The medicines used to prevent a stroke are called anticoagulants. These help to stop blood clots forming in your blood vessels.

The main complication of atrial fibrillation (AF) is an increased risk of having a stroke. AF can interfere with the blood flow in the heart chambers. This sometimes leads to a small blood clot forming in a heart chamber.

A clot can travel in the blood vessels until it becomes stuck in a smaller blood vessel in the brain (or sometimes in another part of the body). Part of the blood supply to the brain may then be cut off, which causes a stroke. Strokes due to AF tend to be even more serious than strokes due to other causes.

The risk of developing a blood clot and having a stroke varies, depending on several factors. The level of risk can be calculated by your doctor using a set of specific questions. This will help to decide what treatments are required. All people except those at the lowest risk will be offered medication to help prevent clots from forming.

Medicines called anticoagulants can be used to reduce the risk of a blood clot and so reduce the risk of stroke. Anticoagulants work by prolonging the time it takes for blood to form a clot. Some people call anticoagulation 'thinning the blood', although the blood is not actually made any thinner.

Anticoagulants reduce the risk of stroke by nearly two thirds. In other words, these treatments can prevent about 6 out of 10 strokes that would have occurred in people with AF.

Your doctor can use a risk assessment to see if you should take medicine to reduce your risk of stroke. The most commonly used risk assessment tool is called the CHA2DS2-VASc risk score. Points are added for each of the following it they apply to you:

The higher the total points score, the higher the risk of stroke. Everyone with a score of 2 or more should be treated with anticoagulation. People with a risk of 1 may be offered anticoagulation.

Another risk score called the HAS-BLED score is used to estimate the risk of major bleeding when you are taking a medicine to reduce the risk of stroke if you have AF. This helps to decide whether or not steps should be taken to reduce your risk of bleeding if you take anticoagulation.

Aspirin is very effective at reducing the risk of a second stroke if you have had a stroke which was not due to AF. However, where AF related stroke is concerned, aspirin is much less effective than other treatments but just as likely to cause problems. It is therefore no longer recommended to reduce the risk of stroke in AF.

Instead, your doctor is likely to recommend an anticoagulant - either warfarin (the traditional option) or one of the newer agents called NOACs:

To find out more about these medicines, including the risks and benefits of the various alternatives, see the separate leaflet called Anticoagulants.

An operation can be used to reduce the risk of stroke for people with AF. The operation is called left atrial appendage occlusion and closes a pouch in the heart, called the left atrial appendage.

The National Institute for Health and Care Excellence (NICE) in the UK has recommended that left atrial appendage occlusion can be considered as a treatment option to reduce the risk of stroke in people with AF. However, it does carry risks. It is usually reserved for people who are at high risk of stroke and who cannot take anticoagulants.

Atrial Fibrillation

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