What Is Atrial Fibrillation?


Atrial fibrillation (AFib), which causes an irregular and often rapid heart rate, is the most common form of cardiac arrhythmia.

Normally, the heart’s upper chambers (the atria) contract in a rhythmic manner to pump blood into the lower chambers (the ventricles), where it’s then pumped out to the rest of the body. In AFib, electrical signals that govern this process go awry and cause the atria to quiver rapidly.

This compromises the ability of the heart to pump optimally.

When the atria don’t contract normally, some blood can pool in them, allowing blood clots to form. These clots can enter the bloodstream and travel, most commonly to the brain, which can cause a stroke. About one in seven strokes is related to AFib.

AFib symptoms can vary from person to person. Some people are fatigued, and it affects their everyday activities. Others find themselves short of breath after a little physical exertion. Other symptoms can include palpitations (irregular, rapid, or pounding sensation in the neck or chest), light-headedness, dizziness, and chest pain or discomfort. Not everyone who develops AFib will experience symptoms, and for those who do, symptoms can range from mild to severe.

AFib is classified as one of four types:

  • Paroxysmal atrial fibrillation is a recurrent condition in which abnormal electrical signals spontaneously begin, typically last for a day or two, sometimes as long as a week, and then suddenly and mysteriously disappear. Symptoms range from barely noticeable to severe.
  • Persistent atrial fibrillation lasts longer than a week and often requires an intervention to be stopped.
  • Long-standing persistent atrial fibrillation is continuous AFib that lasts longer than a year.
  • Permanent atrial fibrillation is less a description of a patient’s AFib than it is of a therapeutic strategy whereby the patient and doctor together have decided not to pursue rhythm control. If a patient has no symptoms, he or she might take anticoagulants and stay in AFib “permanently.”

AFib is typically treated with anticoagulants to prevent blood clots from forming and causing a stroke. Patients may also take antiarrhythmic drugs to restore the heart’s normal rhythm and other medications such as beta-blockers or calcium channel blockers to control heart rate. In some cases, electrical cardioversion—a brief electrical shock delivered to the heart—may be needed to restore normal heart rhythm.

Other treatments include procedures such as radiofrequency or surgical ablation, which destroys the area of the heart that triggers the abnormal rhythm.