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Atrial Fibrillation

Atrial fibrillation is a common type of cardiac arrhythmia, which means the heart beats either too fast, too slowly, or irregularly.

heart provider in scrubs and wearing mask at monitor viewing graphic

What is atrial fibrillation?

Atrial fibrillation is often referred to as AFib or AF for short. It is a common type of cardiac arrhythmia, which means the heart beats either too fast, too slowly, or irregularly.

AFib occurs when the two upper heart chambers, known as the atria, experience irregular beating. The irregular heartbeat in the upper chambers keeps the blood from flowing as well as it should to the lower two chambers, called the ventricles. 

What does AFib feel like?

During AFib, the heart's ventricles and atria are out of sync, causing the heartbeat to become chaotic or rapid. It's common for patients to feel a fluttering or fast heartbeat that can occur on a regular basis, in episodes, or continuously. Some people may never realize they have AFib.

A normal heartbeat starts with a firing of electrical impulses from the right atrium. AFib causes these impulses to fire between both atria instead. This causes too many contractions, and the ventricle cannot keep up with the rapid pace. The ventricles start overworking (beating rapidly) to try to keep up. The result is that blood may not fill up the heart and pump properly through the heart's chambers.

A regular heartbeat is anywhere between 60 to 120 beats per minute. When a heart is experiencing AFib, the heartbeat can range from 100 to 175 beats per minute or even reach up to 400. In some cases, the rapid heartbeat can put a person at risk for a stroke. 

Types of atrial fibrillation

Not all cases of atrial fibrillation are the same. Doctors will classify AFib into one of the following  categories:

  • Occasional: Technically known as paroxysmal atrial fibrillation, this type of AFib has occasional symptoms that may last a few minutes to a few hours
  • Persistent: A persistent case typically lasts longer than seven days. If someone has persistent AFib, their heartbeat will not return to normal on its own and usually requires cardioversion or medication to return to normal
  • Long-standing persistent: When AFib lasts longer than twelve months


Atrial Fibrillation: Risk Factors, Symptoms, and Treatment

Paul Zei, cardiac electrophysiologist at Brigham and Women's Hospital explains how atrial fibrillation is treated and how research is looking to improve those treatment options.

What are AFib symptoms?

There are multiple atrial fibrillation symptoms, but it’s possible someone will never realize they have it. If AFib does cause symptoms, a person might experience the following:

  • Chest pain
  • Dizziness
  • Fainting 
  • Fatigue
  • Racing or fluttering heartbeat
  • Shortness of breath
  • Weakness 

Checking your heart rate

If you are experiencing AFib symptoms, it’s a good idea to check your pulse regularly, record your results, and share them with your care team. For accurate results, you should be in a comfortable position for at least 5 minutes. Avoid measuring your heart rate after exercising, feeling stressed, or consuming caffeine. A normal resting heart rate should be 60 to 120 beats per minute. To check your heart rate manually, follow these steps:

  • Press the tips of your index and middle fingers gently against the side of your neck under your jawline, or on the inside of your wrist below your thumb
  • Count the number of beats you feel for 15 seconds, using a stopwatch or clock for accurate timing
  • Multiply the number of beats by 4; this number is your heart rate

You can also use a device like a smart watch or fitness tracker to check your heart rate.

When to call 911

If you have AFib, you may be at increased risk for both heart attack and stroke. Call 911 immediately if you are experiencing the signs of a heart attack (chest pain or pressure, shortness of breath, pain in the arms, back, neck, or stomach, or nausea) or stroke (face drooping, arm weakness, or difficulty with speech).

What causes AFib?

AFib is caused by numerous factors, many of which are related to the structure of the heart. Still, it’s possible someone without any heart problems or conditions can experience AFib. Possible atrial fibrillation causes include:

Complications from AFib

Although not considered a life-threatening condition, AFib can lead to greater heart complications if left untreated. This includes:

Atrial fibrillation risk factors

AFib is a common condition, but the following risk factors are often associated with it:

  • Older age
  • Moderate to heavy alcohol use
  • Family history of AFib
  • High blood pressure
  • Heart disease
  • Thyroid disease
  • Chronic conditions such as diabetes, lung disease, or sleep apnea 
  • Obesity
  • High levels of stress

Are you experiencing symptoms or have risk factors that may cause atrial fibrillation? The specialists at Mass General Brigham are here to answer your questions about heart health.

Atrial fibrillation diagnosis

Diagnosing AFib involves several steps. Because people may not even realize they are experiencing AFib, it may only be detected when a doctor listens to their heart with a stethoscope. 

Doctors may perform a range of tests to diagnose or rule out AFib or other heart conditions. Most likely, the physician will start with a physical exam and order an electrocardiogram (known as an ECG or EKG). The ECG uses sensors placed on the arms, chest, and legs to measure the electrical currents throughout your body. 

An ECG does not always detect atrial fibrillation since episodes may be hard to pinpoint. Numerous other conditions can have similar symptoms as AFib. For these reasons, a physician may run additional tests, which could include:

  • Blood tests: To rule out thyroid problems or other causes detected in the blood
  • Holter monitor: A portable ECG that monitors electrical activity in your body for 24 hours
  • Event recorder: Another portable ECG that records when a button is pressed in response to an irregular heartbeat
  • Echocardiogram: Images of a heart are created based on sound waves from this test
  • Stress test: Examining the heart during physical activity, including running on a treadmill or a stationary bike
  • Chest X-ray: An X-ray image the doctor uses to see the lungs and heart

AFib treatment options

AFib is a highly treatable condition. Medications, such as beta-blockers, are often prescribed to control the heart’s rhythm. Blood thinners, like anticoagulants, may also be prescribed if the doctor determines there is a risk of stroke.

A medical procedure could be performed if the heart needs help controlling its rhythm. For someone who is in AFib all the time, a cardioversion could be performed. Cardioversion is an electric shock that restores the rhythm to normal. Medications will then be used to maintain a healthy heartbeat.

In some cases, doctors will perform an atrial fibrillation ablation, a minimally invasive procedure where a catheter is inserted into the heart to correct the irregularity. There is also an open heart surgical procedure, called the maze procedure, that is highly effective in curing atrial fibrillation.

How to prevent atrial fibrillation

Maintaining a healthy lifestyle may reduce the chances of an atrial fibrillation episode. A heart-healthy lifestyle means:

  • Eating a nutritious diet
  • Regular exercise
  • Maintaining a healthy weight
  • Avoiding or limiting alcohol use
  • Managing anger and stress

Living with atrial fibrillation

The CDC estimates that more than 12 million people in the U.S. will have atrial fibrillation by 2030, which further illustrates how common the condition is. Many people have the condition their entire lives and are able to live with it as long as it is properly managed.

With the right treatment and proper care under the guidance of a physician, a patient with AFib can lead a normal, active lifestyle.


The most common symptom of AFib is a rapid heartbeat or heart fluttering. Some people never know they have AFib because they never exhibit any symptoms, but other warning signs might include:

  • Fatigue or general lack of energy
  • Lightheadedness or dizziness
  • Chest pain or pressure 
  • Shortness of breath
  • Fainting

It’s important to speak to your physician if you have any concerns about AFib symptoms or suspect you could have the condition.

Atrial fibrillation is not considered a life-threatening condition. It can, however, lead to serious medical conditions if left untreated. A physician can prescribe medications and a treatment plan for proper management of AFib. If left untreated, AFib could lead to other serious conditions, including:

Working under the guidance and supervision of a physician is the first step. After a physical examination and additional tests, a physician may prescribe medications to help control the rhythm of your heartbeat or blood thinners. Additional tests and monitoring may be ordered and possibly a cardioversion, which is an electric shock to the heart. 

People with atrial fibrillation should avoid foods that potentially interact with prescribed medications, such as blood thinners. Since caffeine, tobacco, and alcohol tend to aggravate AFib, a doctor may advise these be excluded from your diet.

During an atrial fibrillation episode, the two upper chambers (known as the atria) beat irregularly due to a faulty misfiring of the electrical signals within the atria. This results in an irregular heartbeat. An atrial flutter is a faster heartbeat, although it is still regular. The atrial flutter means the atria are beating faster than the ventricles, which are the lower chambers of the heart. It’s also possible to experience an atrial flutter and atrial fibrillation simultaneously.

It’s important to consult your physician if you are concerned about atrial fibrillation or other heart conditions. The providers at Mass General Brigham can create a customized treatment plan for you to treat AFib and other heart conditions.