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Atrial Fibrillation

Signs & Symptoms of Atrial Fibrillation

Atrial fibrillation (AF) usually causes the heart's lower chambers, the ventricles, to contract faster than normal.

When this happens, the ventricles can't completely fill with blood. Thus, they may not be able to pump enough blood to the lungs and body. This can lead to signs and symptoms, such as:

What Causes Atrial Fibrillation?

Atrial fibrillation occurs when the electrical signals traveling through the heart are conducted abnormally and become very rapid and disorganized.

This is the result of damage to the heart's electrical system. The damage most often is the result of other conditions, such as coronary heart disease (also called coronary artery disease) orhigh blood pressure, that affect the health of the heart.

Sometimes, the cause of AF is unknown.

Who Is At Risk for Atrial Fibrillation?

Atrial fibrillation (AF) affects millions of people, and the number is rising. Men are more likely than women to have the condition. In the United States, AF is more common among Whites than African Americans or Hispanic Americans.

The risk of AF increases as you age. This is mostly because your risk for heart disease and other conditions that can cause AF also increases as you age. However, about half of the people who have AF are younger than 75.

AF is uncommon in children.

Major Risk Factors

AF is more common in people who have:

  • High blood pressure
  • Coronary heart disease (CHD)
  • Heart failure
  • Rheumatic heart disease
  • Structural heart defects, such as mitral valve prolapse
  • Pericarditis; a condition in which the membrane, or sac, around your heart is inflamed)
  • Congenital heart defects
  • Sick sinus syndrome (a condition in which the heart's electrical signals don't fire properly and the heart rate slows down; sometimes the heart will switch back and forth between a slow rate and a fast rate)

AF also is more common in people who are having heart attacks or who have just had surgery.

Other Risk Factors

Other conditions that raise your risk for AF include hyperthyroidism (too much thyroid hormone), obesity, diabetes, and lung disease.

Certain factors also can raise your risk for AF. For example, drinking large amounts of alcohol, especially binge drinking, raises your risk. Even modest amounts of alcohol can trigger AF in some people. Caffeine or psychological stress also may trigger AF in some people.

Some data suggest that people who have sleep apnea are at greater risk for AF. Sleep apnea is a common disorder that causes one or more pauses in breathing or shallow breaths while you sleep.

Metabolic syndrome also raises your risk for AF. Metabolic syndrome is the name for a group of risk factors that raises your risk for CHD and other health problems, such as diabetes and stroke.

Research suggests that people who receive high-dose steroid therapy are at increased risk for AF. This therapy is used for asthma and some inflammatory conditions. It may act as a trigger in people who have other AF risk factors.

Genetic factors also may play a role in causing AF. However, their role isn't fully known.


Reference: National Heart, Lung and Blood Institute

Last updated April 27, 2017