Patient education: Atrial fibrillation (Beyond the Basics)

ATRIAL FIBRILLATION OVERVIEW — 

Atrial fibrillation (also called AF or "A-fib") is an abnormal rhythm of the heart. It is relatively common, affecting about 50 million adults worldwide. The prevalence increases with age, and most people who develop A-fib are over 65 years of age.

Atrial flutter is a related heart rhythm disorder that overlaps with A-fib with respect to mechanism, management, and prognosis. Some people have A-fib or atrial flutter, and some have both.

WHAT IS ATRIAL FIBRILLATION? — 

In atrial fibrillation (A-fib), the upper chambers of the heart (the atria) do not work correctly because of abnormal electrical activity. During A-fib, the atria quiver or "fibrillate" instead of contracting or squeezing normally. This means that blood is not moved from the atria to the ventricles (lower chambers of the heart) as effectively as it should be (figure 1). This can cause people to feel unwell. The blood that remains in the atria does not move as quickly as normal, which allows blood clots to form. Blood clots that form in the left atrium can leave the heart and travel to the brain, resulting in a stroke.

There are two main types of A-fib:

●Paroxysmal (or intermittent) A-fib – Episodes occur with varying frequency and duration but resolve on their own within seven days.

●Persistent A-fib – This lasts continuously for more than seven days and typically requires treatment to restore a normal heart rhythm (also called "sinus rhythm").

In many (but not all) cases, A-fib starts as paroxysmal and over time progresses to be persistent. The longer the atria fibrillate, the more difficult it is to restore and maintain a normal rhythm.

ATRIAL FIBRILLATION CAUSES — 

The risk of atrial fibrillation (A-fib) increases with age, and it typically occurs in people who have underlying heart disease. Almost any type of heart disease can increase a person's risk of A-fib, but the most common causes are:

●Heart disease due to chronic high blood pressure (hypertensive heart disease).

●Heart attack (also called "myocardial infarction" or MI).

●Heart failure (when the heart does not pump as well as it should).

●Heart valve disease, such as mitral regurgitation or mitral stenosis. (See "Patient education: Mitral regurgitation (Beyond the Basics)".)

●A complication of heart surgery and, less often, after other types of surgery.

Other behaviors and medical problems are also associated with an increased risk of developing A-fib. These include:

●Alcohol and binge drinking – Chronic alcohol use can increase the risk of developing A-fib.

Binge drinkers can also develop A-fib that is usually transient. This often occurs over weekends or holidays, when alcohol intake is excessive. It is sometimes called "holiday heart syndrome." Binge drinking is defined as having multiple drinks (four or more drinks for females and five or more drinks for males) on a single occasion, generally within about two hours.

●Hyperthyroidism – A-fib occurs in about 13 percent of all people with an overactive thyroid gland (called hyperthyroidism). Blood testing to check thyroid function is recommended for anyone with A-fib, since hyperthyroidism is treatable. (See "Patient education: Hyperthyroidism (overactive thyroid) (Beyond the Basics)".)

●Medications – Drugs that stimulate the heart can contribute to the development of A-fib. An example is theophylline (sample brand names: Elixophyllin, Theo-24), which is used to treat asthma and chronic lung disease.

●Sleep apnea – There is some evidence that A-fib may be caused by sleep apnea, a condition in which a person stops breathing for prolonged periods of time while sleeping. If your doctor thinks you might have sleep apnea, they might recommend a sleep study. (See "Patient education: Sleep apnea in adults (Beyond the Basics)".)

●Chronic obstructive pulmonary disease (COPD) – People with COPD commonly have A-fib.

●Obesity – People with obesity have an increased risk of having A-fib. The growing obesity epidemic may be a major reason for the growing number of people with A-fib.

●Diabetes – This is a disorder in which your body does not manage glucose (or sugar) normally. People with diabetes have an increased risk of having A-fib. People with diabetes and A-fib have a higher risk of stroke than other people with A-fib.

●Chronic kidney disease – People with chronic kidney disease have an increased risk of having A-fib. People with chronic kidney disease and A-fib have a higher risk of stroke than other people with A-fib.

Some people with A-fib have no obvious cause. When this occurs in people under age 65, without any associated conditions, the risk of blood clots and stroke is much lower than it is in people who are older or who have known causes of A-fib.

ATRIAL FIBRILLATION SYMPTOMS — 

Some people have no symptoms at all, while others have a variety of symptoms. Mild symptoms can include:

●Unpleasant palpitations or irregularity of the heart beat

●Mild chest discomfort (sensation of tightness) or pain

●A sense of the heart racing

●Lightheadedness

●Mild shortness of breath and fatigue, especially with exercise

Some people have severe symptoms, such as:

●Difficulty breathing (with exertion, exercise, or at rest)

●Fainting, or near fainting, due to a reduction in blood flow to the brain

●Chest pain

●Severe fatigue

Among people with A-fib and chest pain, the chest pain may be due to an increase in the heart's need for oxygen and/or a decrease in the heart's supply of blood and oxygen. Some people with A-fib have narrowing of the blood vessels to the heart, which is called "coronary artery disease." Coronary artery disease decreases how much blood and oxygen is delivered to the heart.

ATRIAL FIBRILLATION DIAGNOSIS — 

Atrial fibrillation (A-fib) is diagnosed with an electrocardiogram (ECG or EKG), which is a test to measure the heart's electrical activity. Sometimes, A-fib is diagnosed with a longer-term ECG recording, such as a Holter or event recorder (devices you can wear over a day or two that monitor heart activity). Wearable heart rhythm monitoring devices (such as smart watches and smartphone applications) can also diagnose A-fib and, in some cases, help providers manage it.

Other tests, such as an echocardiogram (ultrasound), can show if there are heart valve problems or if the heart's main pumping chambers (ventricles) are not working well. Blood tests may be used to screen for thyroid disorders. Occasionally, sleep studies and lung function tests are used to look for sleep apnea or underlying lung disease.

ATRIAL FIBRILLATION TREATMENT — 

There are three main components to the management of atrial fibrillation (A-fib): preventing a stroke, restoring and maintaining a normal rhythm, and controlling the heart rate during A-fib.

Treatment to prevent blood clots — Your doctor will review your medical history to determine if you need treatment to reduce your risk of stroke and other problems caused by blood clots.

A-fib increases the risk of blood clots forming in the heart, which can lead to stroke. A stroke can occur if a blood clot forms in the left atrium and a piece of a clot (called an embolus) travels in the blood stream. When an embolus blocks a blood vessel going to the brain, it can cause a stroke. An embolus can also block blood vessels going to other parts of the body, including the eyes, kidneys, spine, intestines, arms, or legs.

There are two types of treatments to reduce the risk of stroke and other problems from blood clots in people with A-fib:

●Taking an anticoagulant medication reduces your risk of stroke. (See 'Anticoagulant drugs' below.)

●There are also non-medication options for the prevention of stroke. (See 'Left atrial appendage occlusion' below.)

Anticoagulant drugs — Anticoagulants (sometimes called "blood thinners") are the most effective treatment for preventing blood clots in people at high risk of stroke. Taking an anticoagulant medication can reduce the risk of having a stroke by approximately 50 to 70 percent. However, taking an anticoagulant increases your risk of bleeding. Your doctor can talk to you about which anticoagulant is appropriate for you and how to take it safely.

●Oral anticoagulants – These are anticoagulants you can take by mouth. There are a few different options; your health care provider can talk to you about your situation and preferences.

●Drugs that do not need blood tests to adjust dosage – Most people with A-fib are treated with one of the following drugs, which do not need a blood test to adjust dosage: dabigatran (brand name: Pradaxa), apixaban (brand name: Eliquis), edoxaban (sample brand names: Savaysa, Lixiana), and rivaroxaban (brand name: Xarelto).

●Drug that requires a blood test to adjust dosage – For some people with A-fib, the most appropriate anticoagulant is warfarin (brand name: Jantoven). This requires periodic blood tests (sometimes as often as weekly, particularly when you first start taking it) to be sure you are taking the right dose. (See "Patient education: Warfarin (Beyond the Basics)".)

●Other anticoagulants – In some situations, your doctor may prescribe a heparin anticoagulant that is taken by injection under the skin (subcutaneous) or by vein (intravenous).

Left atrial appendage occlusion — This is a procedure to help prevent stroke in people with A-fib. A clot in the heart is most likely to develop in the left atrial appendage or "LAA," which is a small pouch of the left atrium (figure 2). LAA occlusion involves blocking the opening of the LAA. This may prevent a clot from leaving the LAA and causing stroke or other organ damage.

This procedure is an option for some people with A-fib, including some people with a high risk of bleeding while taking an anticoagulant. But some people with A-Fib need to continue taking an anticoagulant after LAA occlusion.

In people with A-fib, LAA occlusion can be performed in two ways:

●Through the skin – A small tube (catheter) is inserted through the femoral vein in the upper leg to place a small mechanical device in the opening of the LAA.

●During heart surgery – If you need heart surgery for another reason, the opening of the LAA may be closed or blocked during surgery. This can be done using staples, stitches, or a small clip.

Cardioversion — Cardioversion is a procedure used for A-fib to "reset" your heart rhythm to a normal rhythm.

Electrical cardioversion — This involves the use of an electrical shock from a device called a defibrillator, delivered by paddles placed on the chest, to "reset" your heart rhythm. Urgent cardioversion is usually performed if A-fib is interfering with the heart's ability to supply blood and oxygen to vital organs. (See "Patient education: Cardioversion (Beyond the Basics)".)

Chemical cardioversion — This involves taking a medicine that can reset your heart rhythm. Sometimes this medicine is given prior to electrical cardioversion to increase the chance of resetting your heart rhythm and keeping it in a normal rhythm.

Timing of cardioversion and anticoagulation

●Early cardioversion – Rarely, people with newly diagnosed A-fib who have had A-fib for a short time can undergo electrical or chemical cardioversion (in which an antiarrhythmic drug is used to reset or restore the normal heart rhythm) within hours of starting anticoagulation.

●Delayed cardioversion – Due to the risk of stroke from blood clots in the left atrium, most people are advised to delay cardioversion until they have been treated with an anticoagulant for many days. Anticoagulant medication is commonly given for at least three to four weeks before cardioversion to allow preexisting blood clots in the left atrium to stabilize or resolve. (See 'Anticoagulant drugs' above.)

After cardioversion, anticoagulation should continue for at least four weeks, but many people need to continue much longer. Many people need to take anticoagulants indefinitely.

Transesophageal echocardiogram — A procedure called a transesophageal echocardiogram (TEE) is an alternative to delaying cardioversion after starting an anticoagulant medication. It involves swallowing a thin tube, which your doctor can then use to view the heart with ultrasound. This allows the doctor to see the left atrium and look for evidence of blood clots. If there is no evidence of blood clots in the left atrium, cardioversion can be performed without four weeks of anticoagulant pretreatment.

Although the TEE can avoid the need for delaying cardioversion for four weeks after starting the anticoagulant, it is still important to be taking an anticoagulant at the time of the cardioversion. This can be an anticoagulant taken by mouth or administered as an injection subcutaneously (under the skin) or intravenously (through a vein). (See 'Anticoagulant drugs' above.)

Although there is still a risk that cardioversion could result in a stroke when a clot is not seen on the TEE, the risk is quite small. Following cardioversion, you will need to continue taking an anticoagulant for at least four weeks, assuming your heart rhythm continues to be normal.

Long-term treatment — For people with persistent A-fib, there are two long-term treatment options: rhythm control and rate control. People who are treated with either of these options are often also treated with anticoagulation to prevent blood clots.

Choosing an approach — Either a rate control or a rhythm control strategy may be appropriate for the long-term treatment of A-fib.

For people with A-fib with one or more of the following features, rhythm control may be more helpful than rate control:

●A-fib started less than one year ago.

●A-fib is causing symptoms.

●The heart is not pumping blood as well as it should. This may or may not cause symptoms (such as shortness of breath).

Your doctor can talk to you about the risks and benefits of each type of treatment. Sometimes goals change during the course of treatment.

Rhythm control — Rhythm control involves trying to restore and maintain a normal heart rhythm (called a sinus rhythm).

Advantages of rhythm control may include reduced symptoms and improved cardiac function. The disadvantages of rhythm control are high rates of recurrent A-fib and complications of treatment. Most people treated with rhythm control need treatment to prevent blood clots, such as an anticoagulant.

Approaches for rhythm control and their complications include:

●Cardioversion and antiarrhythmic drug therapy – After successful conversion to normal sinus rhythm, only 20 to 30 percent of people not taking antiarrhythmic drug therapy are still in sinus rhythm after one year. This can be increased to 50 percent or more with the addition of an antiarrhythmic drug.

Side effects of antiarrhythmic drug therapy include development of new abnormal heart rhythms. Rarely, adverse effects of antiarrhythmic drugs can be life-threatening.

●A-fib ablation – An advantage of A-fib ablation is that it may reduce the need for long-term antiarrhythmic medications. People who have recurrent A-fib despite using one or more antiarrhythmic drugs may be successfully treated with A-fib ablation.

•By catheter – Catheter A-fib ablation destroys the part of the heart that is creating or spreading abnormal electrical signals. Catheter ablation is a procedure that can reduce the frequency of A-fib. It involves using heat ("radiofrequency ablation"), cold ("cryoablation"), laser balloon, or high-voltage electrical pulses ("pulsed field ablation") to destroy the heart tissue that is sending abnormal electrical signals. This is done by a catheter (flexible wire) that is passed from a vein (usually in the upper leg) to the heart and pulmonary veins. (See "Patient education: Catheter ablation for abnormal heartbeats (Beyond the Basics)".)

Complications of A-fib catheter ablation include stroke, pericardial effusion (fluid around the heart), injury of blood vessels, and rare development of a connection between the esophagus (the tube connecting the mouth and stomach) and the left atrium.

•By surgery – Surgical procedures, including the complete "maze procedure" and the less invasive alternative surgeries, may be considered in some people with A-fib, especially those who must undergo open-heart surgery for other reasons. Sometimes surgical techniques are used in combination with catheter ablation in an attempt to cure A-fib (this is sometimes called a "hybrid" or "convergent" procedure). Standalone surgical treatment for A-fib, without concurrent heart surgery or catheter ablation, is not commonly performed.

Complications of surgical A-fib ablation may include poor pumping of the left and right atria and the need to implant a pacemaker.

Rate control — Rate control involves trying to bring the heart rate down to a near-normal level. If you are treated with rate control, you will continue to have A-fib. Most people who are treated with rate control also need an anticoagulant, since there is a risk of blood clot formation and possible stroke.

●Medication – For people with A-fib, the most common way to control the heart rate is by taking a medication (a beta blocker, calcium channel blocker, or, less commonly, digoxin [sample brand names: Digitek, Digox, Lanoxin]) to slow the electrical conduction from the upper heart chambers (atria) to the lower chambers (ventricles). This keeps your heart rate in the normal range. The major disadvantage of using drugs for rate control is that it is sometimes difficult to adequately control the rate and relieve symptoms.

●AV node ablation – Ablation of the atrioventricular (AV) node combined with implantation of a pacemaker is a method of rate control without using drugs. This method may be used when rate control drugs and rhythm control have not worked. The AV node connects the upper part of the heart (atria) with the lower part of the heart (ventricles). When the AV node is ablated, signals cannot pass from the atria to the ventricles. The ventricles beat too slowly on their own, so a pacemaker is implanted to keep the ventricles beating at an adequate rate.

WHERE TO GET MORE INFORMATION — 

Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Atrial fibrillation (The Basics)
Patient education: Implantable cardioverter-defibrillators (The Basics)
Patient education: Pacemakers (The Basics)
Patient education: Catheter ablation for the heart (The Basics)
Patient education: Wolff-Parkinson-White syndrome (The Basics)
Patient education: ECG and stress test (The Basics)
Patient education: Heart failure and atrial fibrillation (The Basics)
Patient education: Tachycardia (The Basics)
Patient education: Atrial flutter (The Basics)
Patient education: Mitral stenosis in adults (The Basics)
Patient education: Supraventricular tachycardia (SVT) (The Basics)
Patient education: Medicines for atrial fibrillation (The Basics)
Patient education: Warfarin and your diet (The Basics)
Patient education: Ambulatory heart monitoring (The Basics)
Patient education: Cardioversion (The Basics)
Patient education: Overview of heart arrhythmias (The Basics)
Patient education: Good sleep hygiene (The Basics)
Patient education: Anticoagulant medicines – Uses and kinds (The Basics)
Patient education: How to take anticoagulants safely (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Mitral regurgitation (Beyond the Basics)
Patient education: Hyperthyroidism (overactive thyroid) (Beyond the Basics)
Patient education: Sleep apnea in adults (Beyond the Basics)
Patient education: Stroke symptoms and diagnosis (Beyond the Basics)
Patient education: Cardioversion (Beyond the Basics)
Patient education: Pacemakers (Beyond the Basics)
Patient education: Implantable cardioverter-defibrillators (Beyond the Basics)
Patient education: Catheter ablation for abnormal heartbeats (Beyond the Basics)
Patient education: Warfarin (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Antiarrhythmic drugs to maintain sinus rhythm in patients with atrial fibrillation: Recommendations
Prevention of embolization prior to and after restoration of sinus rhythm in atrial fibrillation
Atrial fibrillation in adults: Use of oral anticoagulants
Atrial fibrillation: Atrioventricular node ablation
Control of ventricular rate in patients with atrial fibrillation who do not have heart failure: Pharmacologic therapy
Epidemiology, risk factors, and prevention of atrial fibrillation
Atrial fibrillation: Overview and management of new-onset atrial fibrillation
Paroxysmal atrial fibrillation
Atrial fibrillation: Catheter ablation
Atrial fibrillation: Cardioversion
Management of atrial fibrillation: Rhythm control versus rate control
Role of echocardiography in atrial fibrillation
Atrial fibrillation: Surgical ablation

The following organizations also provide reliable health information.

●National Library of Medicine

     (www.nlm.nih.gov/medlineplus/healthtopics.html)

●National Heart, Lung, and Blood Institute

     (www.nhlbi.nih.gov/)

●American Heart Association

     (www.americanheart.org)      

●Heart Rhythm Society

     (www.hrsonline.org)

ACKNOWLEDGMENT — 

The UpToDate editorial staff acknowledges Leonard Ganz, MD, FHRS, FACC, who contributed to an earlier version of this topic review.