Atrial fibrillation (also known as AFib, atrial fib or AF) is one of the most common types of arrhythmia or heart rhythm abnormalities. AFib occurs when the normal electrical pathway in the heart is "overridden" by a clump of cells in the left side of the heart. This bunch of cells fires off electricity rapidly and causes the top chamber to “dance” or quiver. This, in turn, causes the bottom chambers of the heart to beat irregularly, and sometime, faster than normal. According to the CDC:

  • It is estimated that 12.1 million people in the United States will have AFib in 2030.
  • More than 454,000 hospitalizations with AFib as the primary diagnosis happen each year in the United States.
  • AFib increases a person’s risk for stroke, accounting for about 1 in 7 strokes due to its tendency to cause blood clots.

For this and many other reasons, effective treatment for AFib is imperative.

AFib Causes

What causes AFib is not completely understood, but we sometimes refer to it as "the fever of the heart." Essentially, things that put stress on the heart can trigger AFib episodes. These stressors include infection, surgery, excessive caffeine and alcohol, hormone imbalances, high blood pressure, heart failure and sleep apnea (inadequate breathing at night). Additionally, we tend to see more AFib as patients age and the heart electrical signals age over time as well.

Symptoms of Atrial Fibrillation

With atrial fibrillation, the electrical signals in the atria (the two small chambers of the heart) fire fast and chaotically, causing the atria to quiver instead of contract. As a result, electrical signals then arrive in the ventricles in an irregular fashion, causing a rapid and disorganized heartbeat. Additionally, when the atria do not contract effectively, blood may pool and/or clot, putting the patient at higher risk for stroke.

Everyone has a different experience of symptoms when in AFib. Believe it or not, some people have no idea their heart is beating abnormally and feel completely fine. Some people notice shortness of breath and fatigue gradually over several weeks or months. If you experience the following symptoms, it could be AFib. You should see your doctor or go to the emergency department if the symptom are severe.

  • Strange heartbeat sensations
  • Dizziness
  • Fainting
  • Fatigue
  • Shortness of breath and other symptoms 

Typically, unless we are exercising or under stress, we do not notice our heartbeat; but when you are in AFib, you may feel your heart pounding faster or harder. It may feel like your heart is fluttering in your chest, or that there is a sensation of an early or skipped beat.

You may also experience shortness of breath if you are in AFib. You may feel like you are breathing harder or gasping for air when you climb a flight of stairs or walk a long distance. You may need to stop to catch your breath, or you may feel fatigued after doing certain activities that didn't wear you out before.

You may only experience few minutes of AFib symptoms a couple times a year or less, or you may go into AFib and end up staying in it permanently. On average, you would most likely experience a few to several hours a month, but it all depends on the treatment strategy.

AFib Risks

AFib is serious. It is the leading cause of stroke, as inefficient pumping causes blood to pool or become thicker in the heart chambers, increasing the chance of a clot forming, breaking loose and traveling to the brain. In some patients when the heart rate is fast, AFib can promote heart failure as the pumps of the heart are not as efficient as they are in normal rhythm.

AFib can promote heart failure in some patients, especially when the heart rate is fast, because the heart's pumping is not as efficient in AFib as it is in normal rhythm.

Although AFib may cause chest pain in some patients, AFib and heart attacks are two completely different issues. In the "house" known as the heart, AFib in an electrical problem and heart attacks are plumbing problems.

The American Heart Association recognized Froedtert Hospital and Froedtert Menomonee Falls Hospital with its Get With the Guidelines® AFib Gold Award.

Comprehensive Diagnostics

We offer a full range of imaging techniques and diagnostic studies to diagnose AFib. Tests are conducted by electrophysiologists and other physicians who specialize in heart rhythm conditions. Learn more about diagnostic procedures for arrhythmia.

Treating Atrial Fibrillation

AFib is, for most people, a chronic condition that does not go away on it's own. We can work to control the episodes and keep people in normal rhythm most of the time; but AFib seems to come back at one time or another. Some people have paroxysmal AFib where their heart goes into and out of rhythm on its own. These episodes may last minutes to days. Other people get "stuck" in AFib and need a medication or procedure to help keep them out of AFib.

For many patients, a wide variety of treatments are available for AFib, including medications, cardioversion and other procedures. When more aggressive treatment is required physicians may recommend the following to eliminate the source of the irregular heart rhythm.

Experts in AFib Diagnosis and Treatment

Froedtert & MCW physician specialists offer a unique approach for patients with AFib and atrial flutter (a quick heartbeat that can lead to AFib) offering comprehensive diagnosis, treatment and follow-up care.

Patients benefit from the combined expertise of the multidisciplinary team of arrhythmia physician specialists, including electrophysiologists (cardiologists trained in heart rhythm disorders), heart surgeons, cardiologists and other specialists assembled based on the patient’s condition. Learn more about our exceptional staff.


Because we are a leading academic medical center, research is central to our work. Medical College of Wisconsin physicians are continually participating in and conducting significant research studies to further understand the causes of AFib and identify innovative treatments. Our patients can participate in local and national clinical trials, which can give them access to the latest treatment options for AFib.