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What Is AFib?

Contributor: Paul C. Zei, MD
5 minute read
Doctor listening to Afib patient’s heartbeat

A heart arrhythmia is an irregular heart rhythm, and the most common type is called atrial fibrillation (AFib). Numbers are rising, and recent studies estimate that 12.1 million people in the United States will have AFib by 2030.

Paul Zei, MD, a Mass General Brigham electrophysiologist, answers the most searched questions about AFib, including its risk factors, symptoms, and treatment. Dr. Zei is director of the Comprehensive Atrial Fibrillation Program at Brigham and Women’s Hospital, where he cares for heart patients.

During AFib, the signals to your heart become disorganized. The heart’s two upper chambers, or atria, beat chaotically and really fast.

Paul C. Zei, MD
Mass General Brigham

What happens during AFib?

Your heart has four chambers. In a normal heart rhythm, the chambers beat in sync with each other.

“During AFib, the signals to your heart become disorganized,” explains Dr. Zei. “The heart’s two upper chambers, or atria, beat chaotically and really fast.” The irregular contractions cause the walls of the heart to quiver, or fibrillate. This in turn causes an uneven, rapid heart rate which affects the blood flow through the heart.

“AFib isn’t usually deadly, but it is serious and can cause complications,” Dr. Zei says. It can cause blood clots, which puts you at risk for stroke and heart failure.

Atrial flutter vs. AFib

AFib is distinct from another related arrhythmia called atrial flutter. In atrial flutter, the atrial chambers beat regularly, but faster and more frequently than the two bottom chambers of the heart, called the ventricles.

AFib risk factors

The risk factors for AFib include:

  • Older age

  • High blood pressure

  • Sleep apnea (a sleep disorder where your breathing stops and starts repeatedly)

  • European ancestry

  • Metabolic conditions like diabetes, obesity, and hyperthyroidism

  • Heart conditions, including heart disease, heart failure, and enlargement of the heart’s left chambers

  • Chronic kidney disease

  • Lifestyle choices like alcohol use and smoking

Causes of AFib

Some people with AFib may have no underlying heart problems. The most common causes of AFib are problems with the heart’s structure or other forms of heart disease, including:

  • Genetic predisposition

  • Older age

  • Coronary artery disease

  • Heart attack

  • Congenital heart defects (heart defects you’re born with)

  • Heart valve problems

  • High blood pressure

  • Physical stress due to surgery, other illnesses like lung disease, or viral infections

Symptoms of AFib

Some people don’t experience AFib symptoms, but most feel some of the following:

  • Irregular heartbeat

  • Heart palpitations

  • Rapid fluttering or pounding heart rate

  • Chest pain

  • Extreme fatigue

  • Shortness of breath

  • Lightheadedness

  • Fainting

If you experience AFib symptoms, you should see your primary care provider (PCP). They may refer to you to a cardiologist, such as an electrophysiologist, a special type of cardiologist focused on treating the heart’s electrical system.

AFib treatment

“When treating AFib, we take a holistic four-pronged approach,” says Dr. Zei. “We look at the root causes, the symptoms, and also prevention all at once.” Doctors partner with patients to:

  1. Modify risk factors

  2. Control the heart rate

  3. Control the heart rhythm

  4. Prevent blood clots that can lead to stroke

Modify risk factors

“We evaluate the patient’s underlying medical and lifestyle risks,” Dr. Zei says, including family history. It’s important to address underlying conditions like hypertension, obesity, sleep apnea, and diabetes when treating AFib.

Control the heart rate

If the heart rate is too fast, usually doctors prescribe medication to slow it down. Sometimes doctors also recommend a procedure called an AV junction ablation. This permanently disrupts the electrical signals from atria to the ventricles. Your doctor can implant a device called a pacemaker that sets the heart’s rhythm.

If the heart rate is too slow during AFib, the doctor can use a pacemaker or other device to set the correct speed.

AFib medication and procedures to control the heart rhythm

Medication can control the rhythm of the heart. If necessary, doctors perform minimally invasive procedures, including:

  • Cardioversion. This procedure uses large electrode pads on the chest, which send an electrical current to the heart that resets the heart rhythm back to normal.

  • Catheter or cardiac ablation. This procedure uses a thin catheter, that doctors guide through the blood vessels and into the heart. They destroy the heart tissue that causes the AFib (usually in the left atrium)

Prevent blood clots

Blood thinners help prevent blood clots and the strokes they cause.

AFib prevention

AFib can’t always be prevented. But there are some healthy lifestyle habits that may help you lower the risk of heart disease:

  • Exercise regularly.

  • Eat a healthy diet and prevent high cholesterol.

  • Don’t smoke.

  • Avoid or limit caffeine and alcohol.

  • Control your blood pressure and blood sugar.

  • Get better sleep.

  • Manage your stress levels.

Learn about Mass General Brigham Heart services

Headshot of Paul C. Zei, MD


Cardiac Electrophysiologist