Anticoagulants
(Blood Thinners)

• Why does Atrial Fibrillation cause blood clots?

In people with atrial fibrillation, stagnation of blood can lead to blood clots, which can result in blockage to blood vessels in the brain, causing stroke and / or dementia. The blood clots can also interrupt the blood supply to other parts of the body with serious consequences. The risk of stroke in patients with atrial fibrillation can be dramatically reduced by medications which reduce blood clots - these are called anti-coagulant drugs and are often prescribed in patients with atrial fibrillation.

While treatments such as heart rhythm medications, ablation and pacemakers have been shown to reduce symptoms from atrial fibrillation, there is no good evidence that they reduce the risk of blood clots. These treatments should be seen as an addition, not an alternative, to anticoagulants in most people with atrial fibrillation.

• What are the Risks and Benefits of anticoagulants

Any anti-coagulant drug will increase the tendency to bleeding and it is important to balance the risks and benefits of this type of medication but in most cases the benefits outweigh the risks. Until a few years ago the standard anticoagulant drugs were warfarin and aspirin but there are now alternatives which work in a different way to reduce the risks of blood clots. Your doctor will discuss the pros and cons of different anticoagulant drugs.

Factors including age, sex and other medical conditions have a major effect on the risks and benefits of anticoagulant therapy in patients with atrial fibrillation and these should be assessed in making a decision between the patient and healthcare professionals (sometimes this will involve specialist nurses and pharmacists as well as doctors).

• Is Aspirin Effective in Atrial Fibrillation?

Aspirin is relatively ineffective in reducing the risk of stroke in people with atrial fibrillation so it is no longer recommended.

• Is Warfarin the best option?

Warfarin is a long established anticoagulant drug which blocks the production of vitamin K dependent clotting factors. It is very effective if it is closely monitored and controlled but different patients require different dosages and this can be affected by diet and other medications.

• What about Newer Anticoagulants (NOACS)?

The newer anticoagulants, also called thrombin inhibitors and non- vitamin K oral anticoagulants (NOACS) are effective at preventing stroke and generally have a better safety profile than warfarin.

• What does NICE Guidance say?

Guidance from the National Institute of Clinical Excellence (NICE) recommends that patients with atrial fibrillation should be given a choice between warfarin and NOACS if they are starting anticoagulants. This will require careful discussion with their doctor and possibly other healthcare professionals. Click here to access the NICE guidance.