What does this tool measure?

This interactive tool measures the chance of having a stroke in the next 5 years, for people who are age 55 or older and have atrial fibrillation. To calculate your score, the tool uses the information you enter.

This tool is based on information from the Framingham Heart Study. Since 1948 the Framingham Heart Study has studied the progression of heart disease and its risk factors. The data from this study has been used to make a risk assessment.

You should be aware, though, that the tool cannot be applied to everyone. This tool does not work for people who:

• Have mitral valve stenosis or significant left ventricular dysfunction, which interferes with the heart's ability to pump well.
• Are already taking an anticoagulant such as warfarin (Coumadin). Anticoagulants, also called blood thinners, prevent clots from forming and greatly lower the risk of stroke.
• Have had a stroke or transient ischemic attack within 30 days of developing atrial fibrillation. If so, you are already at high risk, and this tool will not work for you.

The values you enter include the most important risk factors for stroke. They are:

• Age and gender. The risk of stroke increases with age. The risk doubles every decade after age 55. Also, among those with atrial fibrillation, women have a higher risk of stroke than men.
• Systolic blood pressure. Systolic blood pressure is the first number of your blood pressure reading. For example, if your reading is 120/80 (120 over 80), your systolic blood pressure is 120 millimeters of mercury (mm Hg).
• Diabetes. Having diabetes increases your risk of stroke. You can help lower this risk by working with your doctor to keep your blood sugar levels in a target range.
• Prior stroke or transient ischemic attack (TIA). If you have had a stroke or a transient ischemic attack (TIA) within 30 days of developing atrial fibrillation, you are already at high risk, and this tool will not work for you. But if you had a prior stroke or TIA before you developed atrial fibrillation, this tool will work for you.

What does your score mean?

Your score will appear in as a value from 1% to 99%. If your score is 5%, it means that 5 out of 100 people with this level of risk will have a stroke in the next 5 years. If your score is 10%, it means that 10 out of 100 people with this level of risk will have a stroke in the next 5 years.

These percentages are one way your doctor can decide if an anticoagulant (blood thinner), such as warfarin, is the right medicine to help lower your risk of stroke. Talk with your doctor about the best way to lower your risk of stroke.

If you are above a 10% risk, talk to your doctor about taking an anticoagulant. You will want to weigh the benefits of reducing your risk of stroke against the risks of taking an anticoagulant. These medicines work well to prevent stroke. But they also increase the risk of bleeding.

If you are at a 10% risk or lower, you may get enough protection from stroke by taking aspirin. 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.

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.

What's next?

Talk to your doctor about how to lower your risk of stroke if you have atrial fibrillation. Medicine and lifestyle changes, such as quitting smoking or eating a heart-healthy diet, can help lower your risk of stroke.

For help deciding if taking an anticoagulant is right for you, see:

Atrial Fibrillation: Should I Take an Anticoagulant to Prevent Stroke?

For help deciding which anticoagulant to take, see:

Atrial Fibrillation: Which Anticoagulant Should I Take to Prevent Stroke?

For more information, see the topic Atrial Fibrillation.

This tool was derived from 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. The Framingham Heart Study is a project of the National Heart, Lung, and Blood Institute, a part of the National Institutes of Health and the U.S. Department of Health and Human Services, and Boston University. More information is available online at www.framinghamheartstudy.org.