Harvard Heart Letter

Stroke risk when you have atrial fibrillation

Now we have a better tool to calculate your chance of a brain attack if you've been diagnosed with afib.

Atrial fibrillation (afib) is among the most common heart rhythm irregularities. During a bout of afib, the usually rhythmic contractions of the heart muscle's upper chambers (the atria) are replaced by an ineffectual quiver that does not completely move blood out of the heart chamber. As a result, blood can stagnate and form clots. These clots can then travel to the brain and cause an ischemic stroke.

More than one in six ischemic strokes can be traced to atrial fibrillation. In people ages 80 and older, the proportion jumps to one in three. What's more, strokes that stem from afib-related clots carry a higher risk of permanent brain damage or death than other ischemic strokes do, says Dr. Robert Giugliano, associate professor of medicine at Harvard-affiliated Brigham and Women's Hospital.

To continue reading this article, you must login.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »