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Atrial Fibrillation: Should I Take an Anticoagulant to Prevent Stroke?
Get the facts
Your options
- Take an anticoagulant medicine to reduce the risk of stroke.
- Don't take an anticoagulant. You may try aspirin or do nothing.
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 an anticoagulant lowers that risk.
- When you take an anticoagulant, also called a blood thinner, you need to take extra steps to avoid bleeding problems, such as preventing falls and injuries.
- Depending on the type of anticoagulant you take, you may have to get regular blood tests and watch how much vitamin K you eat or drink.
- Aspirin may be a good choice if you are young and have no other heart or health problems or if you can't take an anticoagulant safely. Aspirin doesn't work as well as an anticoagulant to reduce your stroke risk. But aspirin is less likely to cause bleeding problems.
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.
How can medicine help if you have atrial fibrillation?
Atrial fibrillation increases your risk of stroke. Taking an anticoagulant can reduce that risk.
The risk of stroke isn't the same for everyone who has atrial fibrillation. But people who have atrial fibrillation are 5 times more likely to have a stroke than are people who don't have atrial fibrillation.1
Anticoagulants such as warfarin and dabigatran can help protect against stroke. Your doctor may recommend that you take an anticoagulant 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.
What are the risks of taking an anticoagulant?
When you take an anticoagulant, your blood clots more slowly than normal. 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. For example, you shouldn't take an anticoagulant if you fall often, drink large amounts of alcohol, or can't control your blood pressure.
When you take an anticoagulant, also called a blood thinner, you need to take extra steps to avoid bleeding problems, such as preventing falls and injuries. With the anticoagulant warfarin, you also need to have regular blood tests and watch how much vitamin K you eat or drink.
You will want to weigh the benefits of reducing your risk of stroke against the risks of taking an anticoagulant, such as an increased risk of bleeding. For example, each year about 2 out of 100 people who take warfarin will have a problem with severe bleeding, and 98 will not.2 And about 3 out of 100 people who take dabigatran will have a problem with severe bleeding, while 97 will not.3 But these are average risks. Your own risk may be higher or lower than average based on your own health.
How well do anticoagulants work?
Anticoagulants like warfarin and dabigatran lower the risk of stroke in people who have atrial fibrillation. 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.
What can you do instead of taking an anticoagulant?
Aspirin may be a good choice if you are young and have no other heart or health problems or if you can't take an anticoagulant (blood thinner) safely. Aspirin doesn't work as well as an anticoagulant to reduce your stroke risk.
If you are at low risk for stroke or can't take an anticoagulant, 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 is less likely than an anticoagulant 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. Your doctor may have you 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 such as warfarin or dabigatran if:
- Your risk of stroke is high and an anticoagulant is the best treatment for you.
- You are willing and able to take the medicine as directed. This includes taking care to prevent falls and getting regular blood tests if needed.
Compare your options
What is usually involved?
- You take a pill once a day (warfarin) or twice a day (dabigatran).
- You may have regular blood tests to make sure that you are taking the right dose.
- You may need to watch how much vitamin K you eat and drink.
- You'll need to let your doctor know of any new medicines you start taking while you are taking an anticoagulant.
What are the benefits?
- Anticoagulants lower the risk of stroke in people who have atrial fibrillation.
What are the risks and side effects?
- Anticoagulants increase your risk of bleeding problems.
- Anticoagulants lower your risk of stroke, but you could still have a stroke.
What is usually involved?
- You may take aspirin every day to reduce your risk of stroke.
- You may try another antiplatelet medicine such as clopidogrel (Plavix).
What are the benefits?
- Aspirin lowers the risk of stroke in people who have atrial fibrillation. But aspirin doesn't work as well as anticoagulants to reduce stroke risk.
- Aspirin is less likely than an anticoagulant to cause bleeding problems.
- You don't need regular blood tests, as you do with the anticoagulant warfarin.
- You don't have to watch how much vitamin K you eat or drink, as you do with the anticoagulant warfarin.
What are the risks and side effects?
- 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 an anticoagulant (blood thinner).
Personal stories
Are you interested in what others decided to do? Many people have faced this decision. These personal stories may help you decide.
What matters most to you?
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 an anticoagulant
Reasons not to take an anticoagulant
I worry about my risk of stroke.
My risk of stroke is low.
I'm confident that I can take an anticoagulant as directed.
I'm worried that I can't take an anticoagulant as directed.
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.
My other important reasons:
My other important reasons:
Where are you leaning now?
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 an anticoagulant
NOT taking an anticoagulant
What else do you need to make your decision?
Check the facts
If you have atrial fibrillation, are you at higher risk of stroke than someone who doesn't have it?
- Yes You're right. Atrial fibrillation increases your risk of stroke, but anticoagulants can reduce that risk.
- No Sorry, that's not right. Atrial fibrillation increases your risk of stroke, but anticoagulants can reduce that risk.
- I'm not sure It may help to go back and read "Get the Facts." Atrial fibrillation increases your risk of stroke, but anticoagulants can reduce that risk.
Are anticoagulants safe for everyone to take?
- Yes Sorry, that's not right. Anticoagulants 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.
- No You're right. Anticoagulants 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.
- I'm not sure It may help to go back and read "Get the Facts." Anticoagulants 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.
Does aspirin work as well as anticoagulants to reduce the risk of stroke?
- Yes Sorry, that's not right. Aspirin doesn't work as well as anticoagulants to reduce the risk of stroke, but it is less likely to cause bleeding problems.
- No You're right. Aspirin doesn't work as well as anticoagulants to reduce your risk of stroke, but it is less likely to cause bleeding problems.
- I'm not sure It may help to go back and read "Get the Facts." Aspirin doesn't work as well as anticoagulants to reduce your risk of stroke, but it is less likely to cause bleeding problems.
Decide what's next
Do you understand the options available to you?
Are you clear about which benefits and side effects matter most to you?
Do you have enough support and advice from others to make a choice?
Certainty
How sure do you feel right now about your decision?
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.
Use the following space to list questions, concerns, and next steps.
Personal Stories
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 a blood thinner to help reduce my risk for having a stroke.
Monty, age 72
I have a lot of balance problems. They might get better over time, but I do worry about falling. I think I'll stick with aspirin for now.
Juan, age 67
I am not overly concerned about bleeding problems from taking a blood thinner, and I'm motivated to follow the instructions to take it as directed.
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
References
Citations
Prevention of stroke in patients with atrial fibrillation (2009). Medical Letter on Drugs and Therapeutics, 51(1313): 41.
Antiplatelet and anticoagulant drugs (2008). Treatment Guidelines From The Medical Letter, 6(69): 29–36.
Dabigatran etexilate (Pradaxa)—A new oral anticoagulant (2010). Medical Letter on Drugs and Therapeutics, 52(1351): 89–90.
Patrono C, et al. (2008). Antiplatelet drugs: American College of Chest Physicians evidence-based clinical practice guidelines (8th edition). Chest, 133(6): 199S–233S.
Other Works Consulted
ACTIVE Investigators (2009). Effect of clopidogrel added to aspirin in patients with atrial fibrillation. New England Journal of Medicine, 360(20): 2066–2078.
Wann LS, et al. (2011). 2011 ACCF/AHA/HRS Focused update on the management of patients with atrial fibrillation (updating the 2006 guideline): A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation, 123(1): 104–123.
Wann LS, et al. (2011). 2011 ACCF/AHA/HRS focused updated on the management of patients with atrial fibrillation (update on dabigatran): A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation, 123(10): 1144–1150.
Last Updated:
August 19, 2011- Medical Review:
- Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology
Adam Husney, MD, MD - Family Medicine
Theresa O'Young, PharmD - Clinical Pharmacy
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