Atrial fibrillation (AFib) is a disorder of the heart found in about 2 million Americans. AF causes the heart's two small upper chambers (the atria) to quiver instead of beating normally. As a result, blood is not pumped completely out of the heart so may pool and clot. If a piece of a blood clot in the atria leaves the heart and becomes lodged in an artery of the brain, a stroke results.
Take this quiz to learn more about AFib and its risks. For more information, visit our Atrial Fibrillation page.