Atrial fibrillation increases your risk of stroke. The risk of stroke isn't the same for everyone who has atrial fibrillation. But on average, people who have atrial fibrillation are 5 times more likely to have a stroke than people who don't have atrial fibrillation.^{footnote 1}

Taking an anticoagulant lowers that risk. These medicines are also called blood thinners, but they don't really thin your blood. Instead, they increase the time it takes for a blood clot to form.

Anticoagulants used for atrial fibrillation are apixaban (Eliquis), dabigatran (Pradaxa), edoxaban (Lixiana), rivaroxaban (Xarelto), and warfarin (Coumadin).

Lowering the risk of stroke

All of these medicines can lower the risk of stroke. How much they can lower your stroke risk depends on how high your risk is to start with.

Warfarin has been used for many years to lower the risk of stroke in people who have atrial fibrillation.

Direct oral anticoagulants (DOACs) are newer. These medicines include apixaban, dabigatran, edoxaban, and rivaroxaban. They work as well as or slightly better than warfarin to lower the risk of stroke.^{footnote 2, footnote 3, footnote 4, footnote 5, footnote 6}

Raising the risk of bleeding

Anticoagulants make your blood clot slower than normal. This raises your risk of bleeding problems in and around the brain, bleeding in the stomach and intestines, and bruising and bleeding if you are hurt. So when you take any anticoagulant, you need to take extra care to prevent bleeding, such as by preventing falls and injuries.

Each year about 1 to 3 out of 100 people who take an anticoagulant will have a problem with severe bleeding inside the body. This means that 97 to 99 out of 100 people will not have a bleeding problem.^{footnote 6, footnote 3, footnote 4, footnote 5} Your own risk of bleeding may be higher or lower than average, based on your age and your own health. For example, your risk may be higher if you have kidney or liver disease.

These medicines are different in a few ways that may play a role in your decision. Your health also plays a role in which medicine is best for you. Your doctor can help you understand the benefits and risks of each medicine based on your health.

If you have certain health conditions, warfarin may be the only anticoagulant you can take safely. For example, if you have a mechanical heart valve or mitral valve stenosis, you can't take a direct oral anticoagulant (DOAC).

Risk of bleeding in the brain

All anticoagulants have a risk of causing bleeding in different parts of the body, including the brain. Bleeding in the brain is very serious. Warfarin has a higher risk of causing bleeding in the brain compared to DOACs.^{footnote 7}

Research studies show that about 12 out of 1,000 people who take warfarin may have bleeding in the brain. This means that 988 out of 1,000 people may not have this bleeding problem. About 6 out of 1,000 people who take a DOAC may have bleeding in the brain. This means that 994 out of 1,000 people may not have this bleeding problem.^{footnote 7}

Blood tests and vitamin K monitoring

When you take warfarin, you'll need to get regular blood tests to make sure you are taking the right dose. And you will need to watch how much vitamin K you eat and drink.

When you take a DOAC, you don't need to have regular blood tests to check if you are taking the right dose and you don't need to watch your vitamin K intake.

Cost

Warfarin usually costs less than DOACs. Warfarin is available as a generic medicine. Generic medicines cost less than brand-name medicines. Some or all of this cost may be covered by your provincial health plan or private health insurance plan.

Stopping bleeding

If you have a bleeding problem or need surgery right away, your doctor may need to quickly reverse the effects of an anticoagulant.

Dabigatran and warfarin. Doctors can use medicines to quickly reverse the effects of these anticoagulants and stop bleeding.

Apixaban, edoxaban, and rivaroxaban. Doctors do not have a medicine that has been proven to quickly reverse the effects of these anticoagulants.

Your doctor may recommend that you try a DOAC if:

• You prefer to take one of these anticoagulants.
• You are able to take the anticoagulant as directed. For example, you are willing to take dabigatran twice a day.
• You've been taking warfarin and have problems keeping a safe level of medicine in your blood.
• You are already taking warfarin and are having a problem with side effects.

Your doctor may recommend that you take or stay on warfarin if:

• You have a mechanical heart valve or mitral valve stenosis. You can't take a DOAC.
• You are already taking warfarin and aren't having any problems keeping a safe level of medicine in your blood.