Atrial fibrillation (A-fib) is an irregular heart rhythm, also known as a type of arrhythmia. It can interrupt the normal flow of blood in the body and increase the risk of blood clots and stroke.

It does not always produce symptoms, but when it does, a person may experience palpitations, chest pain or discomfort, and lightheadedness.

This article looks at how A-fib affects the heart and what symptoms and possible complications a person may experience. It also discusses the treatment options.

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A-fib is the most common clinical arrhythmia worldwide. Estimates suggest that it affects up to 3% of the Western population aged 20 years or older.

The risk of A-fib increases with age, but it can sometimes occur among young people.

People with A-fib may have a much faster heart rate than usual, and the heart does not pump blood around the body efficiently. Blood may collect, or pool, in the heart, increasing the likelihood of clots.

The human heart consists of four chambers: two upper chambers called the atria and two lower chambers called the ventricles.

Every time the heart beats, it pumps blood from the atria into the ventricles and then from the ventricles around the body.

Each heartbeat starts at the top of the heart and travels down. Electrical signals control the rate at which the heart beats and coordinate the blood flow between the chambers.

When a person has A-fib, these electrical signals become distorted, causing the atria to quiver, or twitch, erratically. This is called fibrillation.

During the heartbeat, the heart may not pump all the blood from the atria to the ventricles, and the blood flow does not follow the usual rhythm.

Many people with an irregular heartbeat, or arrhythmia, do not have any symptoms. However, recognizing and treating A-fib early can significantly improve the likelihood of preventing complications.

Not everyone with A-fib will have symptoms, and in those who do, the symptoms may only occur intermittently. The American Heart Association (AHA) says that the most common symptom is a fluttering heart. Other possible symptoms include:

  • palpitations, or the feeling of an irregular heartbeat
  • breathlessness, particularly during exercise or activity
  • chest pain, pressure, or discomfort
  • low blood pressure, dizziness, lightheadedness, and fainting
  • general fatigue
  • confusion or feelings of unease

Doctors advise anyone who has these symptoms — regardless of whether they have already received an A-fib diagnosis — to keep a record of how often they occur and note whether they become more severe.

Sharing this information with a doctor may help them recommend the best treatment.

People with undetected or untreated A-fib have an increased risk of heart failure and stroke.

Changes in the electrical signals in the heart cause A-fib. It can happen to anyone at any age, but it is more common among older people. Other risk factors include:

  • Hypertension: Long-term high blood pressure can place strain on the heart.
  • Pulmonary embolism: This is the medical term for a blood clot in the artery that delivers blood to the lung.
  • Heart disease: People with underlying heart conditions have a higher risk of A-fib. These conditions include heart valve disease, heart failure, coronary artery disease, and heart attack.
  • Alcohol consumption: Although regularly consuming large amounts of alcohol puts people at the highest risk, even modest amounts can be a trigger for some individuals. Other toxic drugs, such as methamphetamine, can also cause A-fib.
  • Family members with A-fib: People with a family history of A-fib may be more likely to experience the condition themselves.
  • Sleep apnea: This can increase a person’s risk of A-fib, particularly when it is severe.
  • Other chronic conditions: Some long-term medical conditions — including thyroid problems, asthma, diabetes, and obesity — may add to the risk.

Doctors tailor the treatments for A-fib so that they are suitable for the person’s age and lifestyle, heart health, and overall health. Some people may only need medications, while others may need surgical procedures to stabilize their heart rhythm. Sometimes, doctors recommend a combination of treatments.

Medications

Prescription medicines can control a person’s heart rate, prevent clots from forming, and, for some people, normalize heart rhythm.

Managing heart rate

If a person’s heart rate is high, bringing it down will prevent heart failure and potentially reduce the symptoms of A-fib.

Several medications can help by slowing signals that tell the heart to beat. These include:

Preventing clots

A doctor may prescribe anticoagulant medications, or blood thinners. These medications make it harder for blood to clot.

Taking blood-thinning medications can increase a person’s risk of bleeding. However, for most people, the benefits of preventing blood clots outweigh the risks of bleeding, particularly if the person is at risk of stroke.

Doctors use the CHA2DS2-VASc score to evaluate the risk of stroke and establish whether a person is likely to benefit from taking blood thinners.

Some blood-thinning medications include direct-acting oral anticoagulants — such as apixaban (Eliquis), rivaroxaban (Xarelto), edoxaban (Lixiana), and dabigatran (Pradaxa) — and, less commonly, warfarin.

Anyone taking warfarin or another anti-clotting agent should make sure that any medical professionals who are treating them are aware of this medication. This is especially important during the treatment of other conditions and before surgeries.

Learn more about blood-thinning medications for heart problems.

Normalizing heart rhythm

Doctors may try to return the heart rhythm to normal using medication. This is called chemical, or pharmacological, cardioversion.

These so-called anti-arrhythmic medications can help convert A-fib into a regular heart rhythm or maintain a regular rhythm.

They include sodium channel blockers, such as flecainide (Tambocor), and potassium channel blockers, such as amiodarone (Pacerone).

However, even after the heart rhythm returns to normal, most people need to take blood-thinning medications.

Procedures

Doctors sometimes recommend surgical procedures alongside medication, particularly if the person is due to have heart surgery for another health condition. The options for surgery may include:

  • Electrical cardioversion: A surgeon will deliver a synchronized electric shock to the heart. This can reset the irregular rhythm to a regular beat. Before carrying out cardioversion, they may perform a transesophageal echocardiogram. This involves inserting a scope down the throat to produce an image of the heart. A surgeon will carry out this procedure to ensure that no clots are present in the heart. If a clot is present, a doctor will prescribe anticoagulant medication for several weeks to dissolve it. Cardioversion will be possible after the clot has dissolved.
  • Catheter ablation: This destroys the tissue that is causing the irregular rhythm. The surgeon may need to repeat this procedure if A-fib returns.
  • Surgical ablation: Surgeons can also remove the heart tissue causing the irregular rhythm by carrying out a form of open-heart surgery called a maze procedure.
  • Pacemaker placement: This device instructs the heart to beat regularly. A surgeon will sometimes place a pacemaker in a person with intermittent A-fib and ablate the native electrical system. This allows the pacemaker to “take over” and ensure that the heart beats regularly.

According to the AHA, for most people with A-fib, the most serious risk is that it can lead to other, life threatening conditions. These include:

Blood clots

Blood can pool in the atria if the heart is not beating regularly. Blood clots can then form in these pools.

A segment of a clot, called an embolus, might break off and travel to different parts of the body through the bloodstream and cause blockages. For example, an embolus can restrict blood flow to the kidneys, intestine, spleen, brain, or lungs. A blood clot can be fatal.

Stroke

A stroke occurs when a blood clot blocks an artery in the brain, reducing or stopping blood flow to part of the brain.

The symptoms of a stroke vary depending on the part of the brain in which the stroke occurs. They can include weakness on one side of the body, vision problems, and speech and movement difficulties.

Stroke is a leading cause of disability and death in the United States.

Heart failure

A-fib can lead to heart failure, especially when the heart rate is high. When the heart rate is irregular, the volume of blood flowing between the heart’s upper and lower chambers varies for each heartbeat. The heart muscle can tire out from beating too quickly and irregularly.

As a result, the heart may not pump enough blood to the body, and the amount of blood waiting to circulate can instead build up in the lungs and other areas.

A-fib can also worsen the symptoms of any underlying heart failure.

Cognitive problems

A 2018 study linked A-fib with a higher long-term risk of cognitive decline and dementia. However, other research from 2019 questions this, saying that the link is unclear. More research is necessary to clarify this.

Although aging and a family history of A-fib are nonmodifiable risk factors, there are many ways to reduce the risk of A-fib and maintain a healthy heart. In 2020, the AHA published a scientific statement saying that lifestyle changes can reduce many of the risks.

Keeping any underlying conditions, such as hypertension or diabetes, under control also reduces the risk of A-fib. The AHA statement and other studies stress the importance of multidisciplinary medical treatment plans.

When it comes to lifestyle, the basic rules of following a nutritious diet, engaging in regular physical activity, and maintaining a moderate body weight are important. People who smoke or drink alcohol can also reduce their risk of developing A-fib by limiting or stopping these behaviors.

This section answers some common questions about atrial fibrillation.

What does atrial fibrillation feel like?

Many people with A-fib experience a rapid heartbeat, which can make it feel as though the heart is missing a beat or pounding in their chest. Other people may feel dizzy, faint, or inexplicably anxious.

People with A-fib may have difficulty breathing, particularly when lying down.

Most people will have these feelings from time to time, but anyone who notices them happening more regularly, or more intensely, may have A-fib.

Is atrial fibrillation life threatening?

A-fib’s irregular heartbeat is not in itself life threatening. The problem is that it increases the likelihood of a person developing blood clots, which can block the blood supply to other organs.

During A-fib, a person’s heart is not pumping efficiently.

What is the life expectancy of a person with atrial fibrillation?

People with A-fib have an increased risk of other heart diseases and stroke, partly because risk factors for the two are overlapping. When the symptoms are under control, many people live a long and active life.

However, a 2020 study suggests that people with A-fib may live 2 years less than people without the condition. The authors stress that the longitudinal study shows that this gap is decreasing.

A-fib is a condition that causes an irregular heart rhythm. It occurs more often after the age of 65 years, and it may not always cause symptoms. The condition can lead to a stroke if blood pools in the heart and forms a clot that travels to the brain.

Lifestyle adjustments can help prevent A-fib. These include prioritizing a heart-healthy diet, limiting alcohol intake, avoiding smoking, maintaining a moderate weight, and getting regular exercise.

Treatment will focus on normalizing the heart rhythm and preventing complications. A doctor may prescribe medications that regulate heart activity and blood-thinning drugs to prevent clots. In certain circumstances, they may recommend surgical procedures.