Health Encyclopedia

Atrial Fibrillation

What is atrial fibrillation?

Atrial fibrillation, or AFib, is a kind of abnormal heart rhythm or arrhythmia. Normally, a specific group of cells begin the signal to start your heartbeat. These cells are in the sinoatrial (SA) node. This node is in the right atrium, the upper right chamber of the heart. The signal quickly travels down the heart’s conducting system. It travels to the left and right ventricle, the two lower chambers of the heart. As it travels, the signal triggers the chambers of the heart to contract. The atria contract with each heartbeat to move blood into the ventricles.

During AFib, the signal to start the heartbeat is disorganized. This causes the atria to quiver or “fibrillate.” The disorganized signal spreads to the ventricles. It causes them to contract irregularly and sometimes quickly. The contraction of the atria and the ventricles is no longer coordinated, and the amount of blood pumped out to the body will vary with each heartbeat. The ventricles may not be able to pump blood efficiently to the body.

The quivering atria can lead to blood pooling. This increases the risk of forming blood clots. These clots can then travel to the brain, causing a stroke. This is why AFib significantly increases the risk for stroke.

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Sometimes AFib occurs briefly and then goes away. This is called paroxysmal atrial fibrillation. AFib that lasts for 7 days or longer is called persistent atrial fibrillation. AFib that lasts longer than a year is called long-standing persistent atrial fibrillation. Persistent AFib may be called permanent atrial fibrillation when a decision is made to no longer control the heart’s rhythm.

AFib is common in adults. The risk increases with age. It is more common in men than women.

What causes atrial fibrillation?

AFib can happen from any type of problem that changes the way the heart handles electricity. Sometimes the cause is unknown. There are a range of problems that can increase this risk. Some of the risks include:

  • High blood pressure
  • Coronary artery disease
  • Heart failure
  • Rheumatic heart disease (from previous Streptococcus infection)
  • Heart valve defects (like mitral valve prolapse)
  • Pericarditis
  • Congenital heart defects
  • Sick sinus syndrome
  • Hyperthyroidism
  • Obesity
  • Diabetes
  • Lung disease
  • Obstructive sleep apnea
  • Metabolic syndrome
  • High-dose steroid therapy

AFib is also more likely to happen during an infection or right after surgery. Stress, caffeine, and alcohol may also set off attacks.

Certain people may be at greater risk of developing AFib. This is due to differences in genes they inherited from their parents. This is not yet fully understood, however.

Who is at risk for atrial fibrillation?

AF is more common in people who are over 65. It’s also more common in men than women. Underlying heart disease, high blood pressure, thyroid problems, excess alcohol use, sleep apnea and certain lung disease put people at risk for atrial fibrillation.

What are the symptoms of atrial fibrillation?

AFib can cause different symptoms. This is especially true when it is not treated. These can include:

  • Heart palpitations — it might feel like your heart is skipping beats or beating too hard
  • Shortness of breath
  • Chest pain
  • Dizziness or fainting
  • Weakness and fatigue
  • Confusion
  • Swelling in the feet, ankles, and legs

Sometimes AFib has no symptoms.

How is atrial fibrillation diagnosed?

Diagnosis starts with a medical history and physical exam. An internist or primary care health care provider will often makes the diagnosis. You may be sent to a cardiologist for further evaluation and treatment.

An electrocardiogram (EKG) is very important for a diagnosis. Health care providers use this test to study the heart signal and rhythm. A skilled reader can find AFib using this test alone. If the AFib comes and goes, you might need an electrocardiogram over a longer period to pick up the rhythm.

Other tests might be used to help plan treatment. These might include:

  • Echocardiogram, to check the hearts structure and function
  • Cardiac stress testing, to check the blood flow in the heart
  • Blood work, to check for thyroid levels, diabetes, and possible medical conditions


How is atrial fibrillation treated?

Your health care providers will work with you to create a specific treatment strategy. Treatment options vary according to your medical history, your symptoms, and your preferences. Some people who don’t have any symptoms may not need a large amount of treatment. Some general categories of treatment include:

  • Anticoagulation medications (blood thinners) or aspirin, to help prevent stroke
  • Medications to slow the heartbeat, like beta-blockers and calcium channel blockers
  • Medications to help prevent AFib (antiarrhythmics)
  • Treatment for the main cause of AFib, if known
  • Medications to treat heart failure (if present), like ACE inhibitors


Before other treatment is started, you may first need a procedure called an electrocardioversion. This can help get the heart back into a normal rhythm. It involves delivering a low-energy shock to the heart to stop the signal that is making the atria quiver.

Procedures such as catheter ablation or maze surgery may be used to restore normal rhythm if medications and electrocardioversion have not worked. Catheter ablation uses radio wave energy sent through a wire. It destroys the small patch of heart tissue that causes AFib. Maze surgery uses cuts or burns in the atria to prevent AFib.

In some cases, the conduction node between the atria and the ventricles (AV node) will be destroyed using catheter ablation. This prevents the problem signals from passing to the ventricles. A pacemaker is then put in to control heart rhythm.

In the long term, treatment focuses on either controlling the heart rate or preventing the abnormal rhythm.

You may be prescribed some type of anticoagulation medication. What you are prescribed will depend on your risk for stroke. If you are at low risk, you may take daily aspirin. If you are at high risk, you will need a stronger blood thinner.

You will need regular follow-up for your AFib. Certain anticoagulation medications call for more frequent blood tests. Tests such as a prothrombin time (PT) will be needed if you take warfarin. This test measures the time it takes for your blood to clot. It records your reading as an international normalized ratio (INR). Your health care provider can change your medication if needed. Newer anticoagulant medications may call for periodic monitoring of your kidney function.


What are the complications of atrial fibrillation?

Stroke and heart failure are the two major complications of AFib. Blood can pool in the atria during AFib. This can cause a clot. This clot can travel to the brain and block a vessel there, causing a stroke. Blood-thinning medications help reduce this risk.

AFib also sometimes causes heart failure. Because the ventricles are beating so irregularly, they can’t fill normally. The atria also can’t squeeze appropriately, which also reduces filling in the ventricles. In some cases, this means the heart can’t pump enough blood to the body, causing heart failure. A rapid heart rate in AFib, left untreated, will increase the risk of heart failure. Heart failure is treated with lifestyle changes, medications, procedures, or surgery. Medications that lower the heart rate will also help prevent heart failure.

Can atrial fibrillation be prevented?

Controlling risk factors for atrial fibrillation may prevent AF from developing. This includes managing underlying heart disease, high blood pressure, thyroid problems, sleep apnea and lung diseases. Risk factor control also means making healthy lifestyle choices. These choices include eating a healthy diet, exercising regularly, maintaining a healthy weight, and not smoking.  Drink only in moderation. If you have an alcohol abuse problem, consider getting help.

How can I manage atrial fibrillation?

There are steps you can take to help you manage your AFib and maintain a healthy lifestyle. They include:

  • Keeping your intake of certain foods consistent, like green leafy vegetables, if you have been prescribed warfarin.
  • Eating a heart healthy diet.
  • Not smoking.
  • Being physically active and maintaining a healthy weight.
  • Keeping your cholesterol at healthy levels with lifestyle and medication.
  • Avoiding the use of alcohol and caffeine (which can trigger abnormal heart rhythms).
  • Avoiding certain over-the-counter medications (which can trigger abnormal heart rhythms).
  • Making sure all your health care providers, dentists, and pharmacists know if you are taking a medication to prevent blood clots.
  • If you miss a dose of a blood-thinning medication, do not double up your dose. Ask your health care provider what you should do.

When should I call my health care provider?

Get emergency medical care if you have severe symptoms like chest pain or sudden shortness of breath. Also get help if you have signs of severe bleeding.

See your health care provider soon if your symptoms are gradually increasing, or if you have any new mild symptoms or side effects.

Key points

  • AFib is a kind of abnormal heart rhythm. The atria quiver instead of contracting the way they should. The heart rate usually increases. It is a serious condition, but most people with AFib can lead normal, active lives. You will need to be checked regularly.
  • Follow all of your health care provider’s instructions about medications, lifestyle, and monitoring.
  • You may be treated with medications to control your heart rate or rhythm.
  • You may need anticoagulation medications to help prevent a stroke.
  • If you receive certain anticoagulation medications, you will need frequent blood tests and monitoring.
  • Go to all your health care provider appointments.


Next steps

Tips to help you get the most from a visit to your health care provider:

  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.

Medical Reviewers:

  • Jones, Niya, MD
  • Petersen, Sheralee, MPAS, PA-C