How does atrial fibrillation affect your stroke risk?

Normally, the heart beats in a regular, steady rhythm. In atrial fibrillation, the two upper parts of the heart (the atria) quiver, or fibrillate, and the heart does not beat in a regular rhythm. Your heart rate also may be faster than normal.

An episode is not usually dangerous. But because the heartbeat isn't regular and steady, blood can collect, or pool, in the heart. And pooled blood is more likely to form clots. Clots can travel to the brain, block blood flow, and cause a stroke.

A stroke can cause sudden numbness or weakness of the face, arm, or leg, especially on one side of the body. Strokes can also cause sudden confusion, trouble speaking or understanding, or even trouble seeing in one or both eyes. Strokes can even cause death.

Atrial fibrillation increases your stroke risk. But not everyone with atrial fibrillation has the same stroke risk.

How do you know what your stroke risk is?

Your doctor can help you know your risk based on your age, sex, and health.

Things that raise your risk are called risk factors. The more risk factors you have, the higher your risk.

Risk factors for stroke include:

• Age. Being older than 65 raises your risk.
• Being female. Women are at higher risk.
• Other health problems. You may have other health problems that raise your risk. These include:
  • Heart failure.
  • High blood pressure.
  • A previous stroke or transient ischemic attack (TIA).
  • Heart attack, peripheral arterial disease, or other blood vessel disease.
  • Diabetes.

Your doctor will use a kind of scorecard to add up your risk factors and estimate your risk for stroke. This score can help you and your doctor decide how to lower your risk.

How can you decide about taking medicine to lower your stroke risk?

When you know what your stroke risk is, you and your doctor can talk about your options. You'll decide whether or not to take medicine—aspirin or anticoagulants—to help prevent blood clots.

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.

Blood thinners 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.

There are risks to taking a blood thinner. When your blood clots more slowly, you have a higher risk of bleeding problems. These problems include bleeding problems in and around the brain, bleeding in the stomach and intestines, bruising and bleeding if you are hurt, and serious skin rash.

You and your doctor can compare your risk of stroke with your risk of bleeding from the medicine. You can also discuss how you feel about taking medicine every day.