Normally, your heart contracts and relaxes to a regular beat. In atrial fibrillation, the upper chambers of the heart the atria beat irregularly quiver instead of beating effectively to move blood into the ventricles. If a clot breaks off, enters the bloodstream and lodges in an artery leading to the brain, a stroke results.
About 15—20 percent of people who have strokes have this heart arrhythmia. Even though untreated atrial fibrillation doubles the risk of heart-related deaths and is associated with a 5-fold increased risk for stroke, many patients are unaware that AFib is a serious condition. Watch an animation of atrial fibrillation. If you or someone you love has atrial fibrillation, learn more about what AFib is, why treatment can save lives, and what you can do to reach your goals, lower your risks and live a healthy life.
Written by American Heart Association editorial staff and reviewed by science and medicine advisers. Strokes caused by complications from AFib tend to be more severe than strokes with other underlying causes. Strokes happen when blood flow to the brain is blocked by a blood clot or by fatty deposits called plaque in the blood vessel lining.
More than , hospitalizations with AFib as the primary diagnosis happen each year in the United States. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Heart Disease. Section Navigation. Facebook Twitter LinkedIn Syndicate. Atrial Fibrillation. Minus Related Pages. What is atrial fibrillation? Secular trends in incidence of atrial fibrillation in Olmsted County, Minnesota, to , and implications on the projections for future prevalence external icon.
Estimates of current and future incidence and prevalence of atrial fibrillation in the U. In atrial fibrillation, the heart's upper chambers atria contract randomly and sometimes so fast that the heart muscle cannot relax properly between contractions. This reduces the heart's efficiency and performance. Atrial fibrillation happens when abnormal electrical impulses suddenly start firing in the atria. These impulses override the heart's natural pacemaker, which can no longer control the rhythm of the heart.
This causes you to have a highly irregular pulse rate. The cause is not fully understood, but it tends to affect certain groups of people, such as older people and people living with long-term chronic conditions such as heart disease, high blood pressure or obesity.
It may be triggered by certain situations, such as drinking too much alcohol or smoking. Atrial fibrillation can be defined in various ways, depending on the degree to which it affects you. Atrial fibrillation is the most common heart rhythm disturbance, affecting around 1. It can affect adults of any age, but it's more common in older people.
Atrial fibrillation is more likely to occur in people with other conditions, such as high blood pressure hypertension , atherosclerosis or a heart valve problem. Our guide to care and support explains your options and where you can get support.
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