What is atrial fibrillation?

Mike Bohl, MD, MPH, ALM - Contributor Avatar

Written by Chimene Richa, MD 

Mike Bohl, MD, MPH, ALM - Contributor Avatar

Written by Chimene Richa, MD 

last updated: Nov 24, 2019

8 min read

Atrial fibrillation (also called AFib or AF) is a fast, irregular heartbeat; it is sometimes described as a quivering or fluttery heartbeat. Atrial fibrillation is the most common heart arrhythmia and typically results in the heart beating too quickly and/or with an irregular rhythm (CDC, 2019). The American Heart Association (AHA) estimates that over 2.7 million Americans are living with AFib, and the amount of people with this condition increases with age (AHA, 2016). According to the Centers for Disease Control and Prevention (CDC), approximately 2% of people under age 65 have AFib in contrast to around 9% of people aged 65 years or older (CDC, 2019). 

Typically, your heart beats with a regular rhythm, allowing the atria (the upper chambers of the heart) to pump blood into the ventricles (the lower chambers of the heart) and then out to the body. However, in atrial fibrillation, the atria of your heart beat much faster and at a different rhythm from the ventricles. The heart rate in afib can range from 100–175 beats per minute; the average heart rate is usually 60–100 beats per minute. This rapid heart rate prevents the ventricles from filling up with blood and, subsequently, less blood gets pumped to the rest of the body. The blood pools in the atria because they are "quivering" rather than fully squeezing all of their blood into the ventricles, leading to blood clots and other problems like strokes. 

There are four different types of atrial fibrillation:

  • Paroxysmal atrial fibrillation: This type of afib only occurs occasionally; your symptoms come and go, lasting anywhere from a few minutes up to a day or even a week. Some people need treatment, while others find that their symptoms get better on their own. You can have multiple episodes of this brief event (paroxysm).  

  • Persistent atrial fibrillation: In this condition, the AFib lasts for longer than a week. Most people end up needing treatment to get their heart rhythm back to normal. 

  • Long-term persistent atrial fibrillation: In this type of AFib, the abnormal rhythm lasts for more than a year without going away.

  • Permanent atrial fibrillation: As the name implies, this type of AFib does not improve with multiple courses of treatment, and you have atrial fibrillation for the rest of your life.


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Risk factors for atrial fibrillation

Risk factors for atrial fibrillation include:

  • Older age: As you age, you are at a higher risk of atrial fibrillation, especially after age 65.

  • High blood pressure: Uncontrolled high blood pressure puts you at an increased risk for atrial fibrillation. This risk factor is thought to contribute to 14–22% of the cases of atrial fibrillation (Mozaffarian, 2015).

  • Race/Ethnicity: Atrial fibrillation is more common among white people in the United States.  

  • Smoking: The risk of atrial fibrillation appears to be higher the longer you smoke and decreases if you quit.

  • Heart disease: If you have heart disease—like coronary artery disease, heart valve problems, congestive heart failure, congenital heart disease, inflammation of the heart, a history of heart attack or heart surgery, or an enlarged heart (cardiomyopathy)—you are at higher risk for developing atrial fibrillation.

  • Obesity: Obese people are at higher risk of developing atrial fibrillation.

  • Alcohol and illegal drugs: Drinking alcohol, especially binge drinking (having five drinks in two hours for men, or four drinks for women), raises your risk of atrial fibrillation. Also, certain illegal drugs, like cocaine, can trigger atrial fibrillation. 

  • Family history: Your chances of having atrial fibrillation are higher if you have a family who also has the condition. 

  • Other chronic medical problems: Other conditions that put you at risk for developing atrial fibrillation include thyroid disease, diabetes, sleep apnea, and chronic lung disease.

Signs and symptoms of atrial fibrillation

Sometimes people with atrial fibrillation do not have any symptoms and are unaware that anything is wrong with their heart; in these cases, the condition is usually diagnosed by their healthcare provider during a physical exam. Other people can have mild to severe symptoms, including:

  • Quivering, racing, irregular heartbeat (palpitations)

  • Fatigue

  • Dizziness or lightheadedness

  • Shortness of breath

  • Weakness

  • Difficulty exercising due to fatigue

  • Chest pain or pressure

  • Fainting, or loss of consciousness

Complications of atrial fibrillation

While having your heart beat erratically or much faster than usual is not a comfortable sensation, it's the complications of atrial fibrillation that are dangerous to your health: these include strokes and heart failure.  

When the atria are "quivering" rather than fully opening and squeezing all of their blood into the ventricles, the blood becomes stagnant and pools, leading to blood clots. These blood clots can then travel to your heart or your brain, causing heart attacks and strokes. People with atrial fibrillation have a four to five times higher stroke risk compared to people without AFib (CDC, 2019). Clinical trials show that atrial fibrillation causes 15–20% of all ischemic strokes, which are a specific kind of stroke due to blood clots in the brain (Mozaffarian, 2015). 

Because of this potential for blood clot formation, heart attacks are also a potential health consequence of atrial fibrillation. Rather than going to the brain, the blood clots can travel along the blood vessels that feed and nourish the heart; a clot in these vessels leads to damage to the heart tissue itself, called myocardial ischemia or heart attack. The risk of a heart attack from atrial fibrillation is highest in the first year after diagnosis, especially among women and African Americans (NIH, n.d.)

Another complication of atrial fibrillation is heart failure, a condition where the heart is not pumping enough blood into the lungs and body; AFib can also make your existing heart failure worse. If the heart cannot effectively pump blood out to the body, the blood can back up into your veins, including those in your lungs. This leads to a fluid buildup in the lungs and causes fatigue and difficulty breathing; fluid also can build up in your feet, ankles, and legs.

How to diagnose atrial fibrillation

As with many other medical conditions, the diagnosis of atrial fibrillation begins with a physical exam. Your healthcare provider will check your heart to make sure that the rate and rhythm are regular and examine your lungs and legs to look for any fluid buildup. If there are any concerns, additional tests exist that can give your provider more information regarding your heart health:

  • Electrocardiogram (ECG or EKG): ECGs look at the electrical signals of the heart and are a standard tool for diagnosing atrial fibrillation. 

  • Holter monitors or event monitors: These are portable ECGs that can measure your heart's electrical activity for extended periods; this gives your provider more insight into how your heart is functioning during daily activities.

  • Echocardiogram: Echocardiograms use sound waves to create a picture of your heart and visualize how the blood is flowing through the different chambers. It can give you information about how well the heart is pumping blood and if there is any pooling of blood or clots. There are two different types of studies: transthoracic echocardiogram (TTE) and transesophageal echocardiogram (TEE). In a TTE, the instrument that makes the sound waves (transducer) is placed on your chest. During a TEE, the transducer is attached to a flexible tube and is guided down your esophagus (throat).

  • Blood tests: Using these tests, your provider can look for thyroid problems or other conditions that may lead to atrial fibrillation.

  • Stress test: You may be asked to exercise (or given medications to make your heart beat faster to simulate exercise) while pictures are taken of your heart to see how your heart functions under stress. 

  • Chest X-ray: A picture of your chest is taken using X-rays to look at your heart and lungs; it may also provide information about conditions other than atrial fibrillation that could be causing your symptoms. 

Treatment for atrial fibrillation

Atrial fibrillation treatment goals are focused on preventing strokes and, in many cases, restoring your normal heart rate and rhythm.

The strategy for preventing strokes involves several different treatment pathways. The first is to adopt a heart-healthy lifestyle, including

  • Eating a diet low in sodium and saturated fat and rich in fruits and vegetables

  • Maintaining a healthy weight; obesity is a risk factor for atrial fibrillation, along with other forms of heart disease

  • Managing stress

  • Exercising several times a week

  • Quitting smoking 

  • Seeking help for alcohol or drug addiction

  • Avoiding stimulants, like caffeine, that can increase your heart rate

Anticoagulants (blood thinners) are the other way that you can prevent strokes. If you have low-risk atrial fibrillation, your provider may recommend that you take an aspirin daily. However, most people need stronger anticoagulants to keep their blood from clotting during episodes of atrial fibrillation and prevent strokes. Commonly used anticoagulants include:

  • Warfarin (brand name Coumadin)

  • Apixaban (brand name Eliquis)

  • Dabigatran (brand name Pradaxa)

  • Enoxaparin (brand name Lovenox)

  • Rivaroxaban (brand name Xarelto)

These medications make your blood less prone to clotting to decrease your stroke risk, but they also increase your risk of bleeding. Make sure to talk to your provider and use all medications as prescribed. 

In addition to preventing strokes, the other treatment question to discuss with your healthcare provider is whether you need your heart rate or heart rhythm (or both) controlled. Getting your heart rate back into a normal range is important because it allows the ventricles enough time to fill with blood completely. You can still have the abnormal heart rhythm, but you may feel better and have fewer symptoms with a slower heart rate. There are several types of medications that your provider may prescribe to treat the fast heart rate associated with atrial fibrillati

  • Beta-blockers Examples are metoprolol and atenolol; side effects include low blood pressure (hypotension)

  • Calcium channel blockers: Examples are verapamil and diltiazem

  • Digoxin: This medication may control the heart rate but can lead to other arrhythmias, so it must be used with caution and is not appropriate for everyone (Lopes, 2018).

Your provider may attempt to reset your heart rhythm back to its regular rhythm (also called normal sinus rhythm); this process is called cardioversion and can be accomplished in two ways:

  • Cardioversion with medications: You are given drugs called antiarrhythmics to help restore normal heart rhythm

  • Electrical cardioversion: This is a short procedure where a brief, low-energy electrical shock is delivered to your heart through patches (electrodes) on your chest. You are given a sedative so that you don't feel the electric shock. The electric shock allows your heart's electrical activity to reset to normal sinus rhythm

Both types of cardioversion are done in the hospital so that your heart function can be monitored the entire time. You may be given anticoagulants days to weeks before cardioversion to prevent blood clots in the heart.

For some people, medication and cardioversion are not sufficient to control their atrial fibrillation; these cases may require a surgical procedure. One possibility is to insert a pacemaker. A pacemaker is a small electrical device that is implanted into the body and regulates the heartbeat. It is implanted under the skin with wires that travel to the heart to control the rate and rhythm. When it senses that the heartbeat is too fast or too slow, it sends an electrical impulse to the heart to restore the normal rate and rhythm. Another surgical procedure, called ablation, kills the heart tissue that is causing the abnormal electrical signals to allow your heart to beat with a normal rhythm again. Ablation can be done via a catheter or open-heart surgery.

  • In catheter ablation, a thin tube is inserted into a blood vessel in your groin and guided into your heart. Once in the heart, the catheter tip can use extreme heat or cold to destroy the areas of the heart producing the abnormal electrical signals and causing the fast, irregular heartbeats. The resulting scar tissue that forms can also encourage the heart's electrical impulses to remain regular. 

  • Sometimes an atrioventricular (AV) node ablation is needed. In this procedure, the catheter is used to destroy a group of special cells, called the AV node, that sit between the atria and ventricles and are responsible for the electrical communication between the two. Afterward, the atria will still quiver and beat abnormally, but the signal won't get to the ventricles. A pacemaker is implanted in the ventricles to control the rate at which the heart beats.

  • Lastly, in a surgical ablation, the surgeon performs open-heart surgery and cuts the abnormal heart tissue, creating scars that interfere with the irregular electrical impulses; this allows the heart to return to a normal rhythm. This procedure is called a maze procedure and can be combined with other heart procedures, like valve replacements, or can be performed on its own. 

How to prevent atrial fibrillation

The best way to prevent the onset of atrial fibrillation is to maintain a heart-healthy lifestyle, which includes:

  • Eating a diet low in sodium and saturated fat and rich in fruits and vegetables

  • Maintaining a healthy weight

  • Managing stress

  • Exercising several times a week

  • Quitting smoking 

  • Seeking help for alcohol or drug addiction

  • Controlling your blood pressure, cholesterol, diabetes, and any existing heart disease

If you have already have atrial fibrillation, the best way to prevent complications from your afib is to follow your provider's instructions with regards to medication. Maintain open lines of communication with your provider and inform him or her of any new or worsening symptoms.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

November 24, 2019

Written by

Chimene Richa, MD

Fact checked by

Mike Bohl, MD, MPH, ALM

About the medical reviewer

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.