Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2002;66(2):271-272

What is atrial fibrillation?

Atrial fibrillation is an irregular heartbeat that may be very fast. (Say: ay-tree-all fib-rill-ay-shun.)

Your heart has four chambers. (You could think of the chambers as “rooms.”) The atria are the two top chambers. (Say: ay-tree-ah.) The ventricles are the two bottom chambers. (Say: ven-trick-ells.)

In atrial fibrillation, the atria stop making a normal, regular electrical signal. Instead, they tremble (fibrillate) in a disorganized way. The fast and disorganized signal is sent to the ventricles. This strange signal causes an irregular and sometimes very fast heartbeat.

Who gets atrial fibrillation—and why?

Atrial fibrillation is most common in people older than 60 years. However, you can get atrial fibrillation at any age.

Sometimes, atrial fibrillation has no known cause. Often, it has one of these causes:

  • Heart disease caused by the build-up of cholesterol in the arteries of the heart

  • A bigger heart size because of high blood pressure

  • Damage to a heart valve

  • An overactive thyroid gland

  • Lung disease, often caused by smoking

  • Heavy drinking of alcohol

  • Some medicines

How can my doctor and I tell that I have atrial fibrillation?

The most common symptom of atrial fibrillation is the feeling of having an irregular, fast heartbeat. The name for this feeling is palpitations. Weakness, a tired feeling, and shortness of breath are other common symptoms. Chest pain can also be a symptom of atrial fibrillation.

Sometimes, the first symptom is a stroke. You might get a stroke if blood clots form in the left side of your heart, break off, and travel up to your brain.

Sometimes there are no symptoms. In some people, atrial fibrillation is discovered because they have an irregular pulse. Or, atrial fibrillation may be seen on an electrocardiogram (ECG) that they have for another reason. The ECG confirms the diagnosis.

How is atrial fibrillation treated?

The treatment for atrial fibrillation depends on how bad your symptoms are. It also depends on whether you have heart disease or recently had a stroke.

If the fibrillation is new and you are having a lot of symptoms, you might be treated with electrical cardioversion. (Say: kar-dee-oh-ver-shun.) For this treatment, you are given a medicine to keep you calm. Then your heart is given an electric shock to make it return to normal rhythm.

If your symptoms are mild, you might be given medicine to make your heart rate slower. If the atrial fibrillation does not go away, you might have electrical cardioversion.

You might be given a blood-thinning medicine like aspirin, heparin, or warfarin (brand name: Coumadin). You will need to take these medicines if you are going to have cardioversion, if you had a stroke at some time, or if your doctor thinks you are at risk for having a stroke in the future.

Your doctor might want you to use less caffeine, alcohol, and other stimulants, or stop using them at all. Stimulants can affect your heart rate.

What can I expect in the future?

Treating the cause of your atrial fibrillation often returns your heart to normal rhythm. If the cause is not treatable, you might need to keep taking medicine to control your heart rate.

You should take your medicine just the way your doctor tells you. If you are taking a blood-thinning medicine, you will need to have blood tests regularly.

Stroke is one problem that can happen because of atrial fibrillation. You are less likely to have a stroke if you take your medicine carefully, so that blood clots do not form.

Call your doctor right away if you have any of these problems:

  • chest pain

  • palpitations

  • shortness of breath

  • bleeding

  • falling

If you have any of these problems, you might be having complications from the atrial fibrillation or from the treatment for it.

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