Understanding Risks of Stroke and Blood Thinners
If you have atrial fibrillation
(AFib), your heart beats irregularly. As a result, your heart has a harder time pumping blood out and to the body. When this happens, blood can pool in the heart and form clots. If a blood clot travels through the bloodstream, it can block a blood vessel in the brain and cause a stroke
Stroke is a serious part of AFib
On average, people with AFib are 5 times more likely to suffer a stroke
than those with a normal heartbeat. Strokes related to AFib are often more severe than strokes from other causes. What does that mean for you or a loved one who has AFib? When a stroke happens, it tends to be debilitating, often leaving someone fully dependent on others for daily tasks such as dressing, getting in and out of bed or doing other tasks. It might also steal your ability to talk or think clearly. Stroke is a leading cause of death and disability.
MORE: What is a Stroke?
The good news is that blood thinners, also called anticoagulants, can be used to lower the risk of stroke. It is estimated that 3 out of 4 AFib-related strokes can be prevented. This is why a doctor may prescribe an anticoagulant for people with AFib.
How Blood Thinners Work
(Click to view)
Blood thinners work by reducing the ability of the blood to clot. But as with all medications, blood thinners have side effects. In preventing blood clots from forming, there is also a higher risk for bleeding in some people. Usually, the bleeding is minor—for example, bruising more easily, or having a nosebleed or cut that takes longer to stop bleeding. However, some bleeding can be serious.
For many patients, the benefits of taking a blood thinner far outweigh the risk of bleeding, according to cardiologists. Even when bleeding does occur, it can usually be managed and is rarely life-threatening.
But research and clinical experience suggest that many patients—and even some clinicians—may worry more about the possibility of uncontrolled bleeding when taking a blood thinner than on the benefit of stroke prevention. It’s important to put these risks in context.
What We Mean by Risk
is the chance, or likelihood, that something will happen.
For example, people over 80 years of age have a 10% risk of developing AFib. In other words, 10 out of 100 (or 1 in every 10) people in this age group will have AFib.
Using the CHA2DS2-VASc risk scoring
(a tool used to predict the chances someone with AFib will have a stroke), if you are 75 years or older and have diabetes and high blood pressure, your score is 4. This means your risk of having a stroke in the next year is nearly 5%—4.8% to be exact. In other words, among people who have these conditions, nearly 5 out of 100 will have a stroke.
A score of 6 ups the risk of stroke to 9.3%—meaning 9 out of 100 people will have a stroke this year.
“In general, most bleeding [related to anticoagulants] can be managed successfully and do not result in irreversible damage (with the exception of intracranial bleeding, which is very rare). In contrast, strokes are more likely to cause disability and can be life-altering, especially for young people,” said Mikhael F. El-Chami, MD, a heart specialist at Emory Healthcare, adding that some stroke victims can no longer live alone or take care of themselves.
While the likelihood of a major bleed from taking an anticoagulant is 2%-3% on average, the risk of stroke is higher. On average, the risk of having a stroke is 5% each year among people with AFib. The trick is that two people with AFib may have very different risks of stroke and bleeding. That’s why reviewing your risks of both stroke and bleeding and making an informed decision with input from your doctor is important.
The good news is there are many options nowadays for blood thinners. “We have more options than ever,” said Dr. El-Chami. “Some of the newer anticoagulants have lower risks of bleeding compared with warfarin, and all of the newer drugs have a lower risk of bleeding in the brain (intracranial hemorrhage).”
It’s important to talk with your doctor about your risk of stroke and bleeding, and your risk for either or both may change over time.
For help in making a decision about blood thinners, use this tool created for patients.
Calculating Stroke and Bleeding Risk
Your health care provider may use a number of tools to assess your risk of stroke to make an informed decision about whether a blood thinner is right for you.
For example, your health care provider may use a formula called the CHA2DS2-VASc to calculate your risk of stroke. This score is based on your age and history of several health issues. Each risk factor is assigned 1 or 2 points, for a maximum score of 9.
| Congestive Heart Failure
| High Blood Pressure
| A2: > 75 years old
| Diabetes (type 2)
| Stroke or Mini-Stroke
| Vascular Disease (heart attack, peripheral artery disease)
| Age: 65-74 years old
| Sc: Female Sex
What your points mean:
0 = Low likelihood of stroke; no blood thinner is likely needed
1 = Low-moderate risk
2 or more = High risk
What does this all mean? Your CHA2DS2-VASc score can:
1) Inform treatment decisions about whether you need a blood thinner.
2) Predict your risk of stroke in the next year. For example, if your total score is 3, it means you have a 3.2% chance of having a stroke in the next year. If your score is 6, the risk jumps up to a nearly 10% chance. Talk to your health care team to ask about your risk over time.
Also, there are tools to help you and your health team estimate your bleeding risk. This information will help determine if you can safely take an anticoagulant, which one might be best, and how often you might need regular follow up. Some people have a higher risk of bleeding due to other health problems or medications they take. Ask your doctor to review what increases your risk of bleeding.
Questions to Ask
Your health care provider should work with you to choose a blood thinner that’s right for you. What works for some people may not for others. Many factors can influence the choice of blood thinner.
- Cost. You will want to know what your insurance will cover.
- Dietary restrictions. For example, talk with your doctor if you are a vegetarian or like leafy greens. Those foods can affect how warfarin works.
- Dosage (the amount). If you have a preference between taking medicine once or twice daily is taken into account. Whatever the frequency, taking your medications as prescribed is essential
- Blood tests. Some patients will need to get blood tests often. People taking warfarin need routine blood testing (usually every 2-3 weeks) to watch how quickly their blood clots and to be sure they stay within a therapeutic range.
Here are some questions to you may want to ask:
- Why do I need to take an anticoagulant?
- How long will I need to take it?
- If I get an ablation for AFib, do I still need anticoagulation?
- If I undergo a cardioversion for AFib, do I still need anticoagulation?
- What are the pros and cons of the different anticoagulants? Which one is best for me?
- What is my personal risk of stroke? How does this compare with my risk of having a serious bleeding event when taking this medicine?
- Will I have any dietary restrictions?
- What is my risk of bleeding?
- How do we make sure I’m not getting too much (if I’m out of therapeutic range)?
- What happens if I fall while taking this medication?
- Do I need to stop doing certain activities when taking this medication?
- What should I pay attention to that would be a sign of bleeding?/What are the signs that I might be having serious bleeding?
- Do I need to tell someone if I need dental work done or surgery?
- Are there any medications I should stop taking (for example, aspirin or NSAIDs)?
- Should I let you know if I start bruising more than usual?
For some people who have repeated bleeding or are deemed to be at high risk for bleeding, placement of a left atrial appendage occlusion device is a reasonable alternative to taking an anticoagulant. This appendage is a small, ear-shaped pouch where blood can collect. There are other options you can discuss with your doctor.
To learn more, CardioSmart has a wealth of tools about AFib, stroke and blood thinners. Some resources include:
Decision Guide: Blood thinners for Atrial Fibrillation
This risk calculator
can help you decide together with your health team if a blood thinner is right for you.
CardioSmart’s Condition Center on Atrial Fibrillation
Living with AFib: Experts and Patients Share 10 Tips
CardioSmart’s Condition Center on Stroke
In addition to the resources on CardioSmart.org, you can find out more by visiting:
American Stroke Association
U.S. National Library of Medicine
Published: May 2017
Editorial Team Lead: Mikhael F. El-Chami, MD, FACC
Medical Reviewer: Anastasia L. Armbruster, PharmD