Atrial fibrillation: Should I take anticoagulants to prevent stroke?

Get the facts
Compare your options
What matters most to you?
Where are you leaning now?
What else do you need to make your decision?

1. Get the Facts

Your options

Take anticoagulants to reduce the risk of stroke.
Don't take anticoagulants. You may try other medicines.

Key points to remember

Atrial fibrillation increases your risk of stroke. High blood pressure, heart failure, a previous stroke, or being 75 or older can also put you at high risk for stroke. Taking anticoagulants, such as warfarin, lowers that risk.
Warfarin may not be safe for you if you fall often, can't control your blood pressure, have stomach bleeding, or drink large amounts of alcohol.
Aspirin may be a good choice if you are young and have no other heart or health problems or if you can't take warfarin safely. Aspirin doesn't work as well as warfarin to reduce your stroke risk. But aspirin is less likely to cause bleeding problems.
When you take anticoagulants, you need to have regular blood tests to make sure that you are taking the right dose. You'll need to take enough medicine to lower your risk of stroke, but not so much that you have a problem with bleeding.

FAQs

What are anticoagulants?

Anticoagulants are medicines that help prevent blood clots. Blood clots can lead to stroke. These medicines are often called blood thinners, but they don't actually thin your blood. Instead, they increase the time it takes for a blood clot to form.

The most commonly used anticoagulants are warfarin and heparin.

Why is it important to take medicine if you have atrial fibrillation?

Atrial fibrillation increases your risk of stroke. Anticoagulants, such as warfarin, reduce that risk.

The risk of stroke isn't the same for everyone with atrial fibrillation. But people who have atrial fibrillation are 5 to 6 times more likely to have a stroke than are people who don't have atrial fibrillation.¹

Anticoagulants provide the best protection against stroke, if you can take them safely. Your doctor may recommend that you take them if you are at high risk for stroke based on your risk factors. Anything that increases your risk for a disease or problem is called a risk factor. The more risk factors you have, the greater your chance of having a stroke.

Risk factors for stroke besides atrial fibrillation include:

Previous transient ischemic attack or stroke.
An artificial heart valve.
Rheumatic mitral valve disease.
High blood pressure.
Heart failure.
Lower than normal ejection fraction.
Age 75 years or older.
Diabetes.
Coronary artery disease.

If you are 55 or older, you can find out your risk of having a stroke in the next 5 years with this Interactive Tool: What Is Your Risk for a Stroke if You Have Atrial Fibrillation?

What are the risks of taking anticoagulants?

Anticoagulants slow the amount of time it takes for your blood to clot. This increases your risk of bleeding problems in and around the brain, bleeding in the stomach and intestines, bruising and bleeding if you are hurt, and serious skin rash.

Some people can't take anticoagulants, because they have a higher risk of having a serious problem if bleeding occurs. You shouldn't take anticoagulants if:

You have blood in your stool for no clear reason.
You can't control your blood pressure.
You fall often.
You won't be able to take the medicines as prescribed.
You drink large amounts of alcohol.
You aren't able or willing to have regular blood tests.

When you take anticoagulants, you need to have regular blood tests to make sure that you are taking the right dose. You'll need to take enough medicine to lower your risk of stroke, but not so much that you have a bleeding problem.

If you have atrial fibrillation and are pregnant or are thinking about getting pregnant, talk with your doctor before taking warfarin. It may cause birth defects and problems during pregnancy.

How well do anticoagulants work?

Anticoagulants significantly reduce the risk of stroke in people who have atrial fibrillation.² But how much your risk will be lowered depends on how high your risk was to start with. Not everyone with atrial fibrillation has the same risk of stroke. It's a good idea to talk with your doctor about your risk.

You will want to weigh the benefits of reducing your risk of stroke with the risks of taking anticoagulants. Warfarin works well to prevent stroke. But warfarin also increases the risk of bleeding. Each year about 2 out of 100 people who take warfarin will have a problem with severe bleeding, and 98 will not.³ But this is an average risk. Your own risk may be higher or lower than average based on your own health.

What can you do instead of taking anticoagulants?

Aspirin may be a good choice if you are young and have no other heart or health problems or if you can't take warfarin safely. Aspirin doesn't work as well as warfarin to reduce your stroke risk. But aspirin is less likely to cause bleeding problems.

If you are at low risk for stroke or can't take warfarin, your doctor may recommend that you take aspirin. Aspirin is an antiplatelet medicine. It decreases the risk of blood clotting by preventing the smallest blood cells (platelets) from sticking together and making a clot.

Aspirin lowers the risk of stroke in people with atrial fibrillation but not nearly as much as warfarin does. How much your risk will be reduced depends on how high your risk was to start with.

Aspirin is less likely than anticoagulants to cause bleeding problems. Bleeding that is bad enough to need treatment in a hospital happens in 1 or 2 out of 1,000 people who take aspirin.⁴ This means that 998 or 999 out of 1,000 people who take aspirin don't have serious bleeding.

Other antiplatelet medicines, such as clopidogrel (Plavix), may be used. You may take them with aspirin or instead of aspirin. When aspirin and clopidogrel are used together, they may reduce the risk for stroke more than aspirin alone. But this combination is also more likely to cause bleeding than aspirin alone.

Why might your doctor recommend taking an anticoagulant?

Your doctor may advise you to take an anticoagulant if:

Your risk of stroke is high and anticoagulants are the best treatment for you.
You are able to take anticoagulants safely.
You are willing and able to get regular blood tests.

2. Compare Options

	Take anticoagulants to reduce the risk of stroke	Don't take anticoagulants
What is usually involved?	You take a pill, such as warfarin, every day. You have regular blood tests to make sure that you are taking the right dose.	You may take aspirin every day to reduce your risk of stroke. You may try another antiplatelet medicine.
What are the benefits?	Warfarin lowers the risk of stroke by more than half (64%).²	Aspirin lowers the risk of stroke in people with atrial fibrillation, but not nearly as much as warfarin does.² Aspirin has a low risk of causing bleeding problems. You avoid the risks and costs of taking warfarin.
What are the risks and side effects?	Warfarin increases your risk of bleeding problems. Warfarin may cause birth defects if you take it while you are pregnant. Warfarin lowers your risk, but you could still have a stroke.	If you have atrial fibrillation and don't take any medicine, you might have a stroke. Aspirin can reduce your risk, but you could still have a stroke. Your risk of having a stroke is higher than it would be if you took warfarin.

Personal stories

Are you interested in what others decided to do? Many people have faced this decision. These personal stories may help you decide.

If you need more information, see the topic Atrial Fibrillation.

Personal stories about taking anticoagulants

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

"I have other risk factors for stroke besides atrial fibrillation. My doctor and I decided that it is important for me to take anticoagulants to help reduce my risk for having a stroke. "

— Monty, age 72

"I live on a ranch more than 100 miles from my doctor's office. I don't plan on checking in with him every week to have my blood tested. Other than my atrial fibrillation, my doctor says my heart is strong as an ox and I'm healthy as a horse. I'm not worried about having a stroke, but I'm going to take aspirin every day. "

— Chuck, age 48

"I am not overly concerned about bleeding problems from taking anticoagulants, and I am comfortable having my blood tested regularly to make sure the medications are working correctly. "

— Martha, age 64

"I have a bleeding ulcer that I am caring for, so I am not a good candidate for blood thinners. "

— Geraldo, age 52

3. Your Feelings

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

Reasons to take anticoagulants

Reasons not to take anticoagulants

I worry about my risk of stroke.

I think that my risk of stroke is low.

More important

Equally important

More important

I don't mind having regular blood tests.

I'm don't want to get my blood tested regularly.

More important

Equally important

More important

Lowering my risk of stroke is more important to me than the risk of a bleeding problem.

I'm more worried about my risk of a bleeding problem than my risk of stroke.

More important

Equally important

More important

My other important reasons:

More important

Equally important

More important

4. Your Decision

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

Taking anticoagulants

NOT taking anticoagulants

Leaning toward

Undecided

Leaning toward

5. Quiz Yourself

Check the facts

1. If you have atrial fibrillation, are you at higher risk of stroke than someone who does not have it?

Yes
No
I'm not sure

You're right. Atrial fibrillation increases your risk of stroke, but anticoagulants such as warfarin can reduce that risk.

2. Are anticoagulants safe for everyone to take?

Yes
No
I'm not sure

You're right. Anticoagulants such as warfarin may not be safe for you if you fall often, can't control your blood pressure, have stomach bleeding, or drink large amounts of alcohol.

3. Does aspirin work as well as warfarin to reduce the risk of stroke?

Yes
No
I'm not sure

You are right. Aspirin doesn't work as well as warfarin to reduce your risk of stroke, but it is less likely to cause bleeding problems.

Decide what's next

1. Do you understand the options available to you?

2. Are you clear about which benefits and side effects matter most to you?

3. Do you have enough support and advice from others to make a choice?

Certainty

1. How sure do you feel right now about your decision?

Not sure at all

Somewhat sure

Very sure

2. Check what you need to do before you make this decision.

I'm ready to take action.
I want to discuss the options with others.
I want to learn more about my options.

3. Use the following space to list questions, concerns, and next steps.

References

Citations

Wang TJ, et al. (2003). A risk score for predicting stroke or death in individuals with new-onset atrial fibrillation in the community: The Framingham heart study. JAMA, 290(8): 1049–1056.
Hart R, et al. (2007). Meta-analysis: Antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation. Annals of Internal Medicine, 146: 857–867.
Antiplatelet and anticoagulant drugs (2008). Treatment Guidelines From The Medical Letter, 6(69): 29–36.
Patrono C, et al. (2008). Antiplatelet drugs: American College of Chest Physicians evidence-based clinical practice guidelines (8th edition). Chest, 133(6): 199S–233S.