Atrial Fibrillation
Atrial Fibrillation

Atrial Fibrillation Causes and Risk Factors


Changes to the tissue that makes up the heart and to the heart’s electrical signals most often lead to atrial fibrillation. To understand atrial fibrillation, it helps to know how the heart works.

What causes atrial fibrillation?

When the heart’s tissue or electrical signaling is damaged, the regular pumping of the heart muscle can become fast and irregular. Most often, this type of damage to the heart is caused by other conditions such as high blood pressure and coronary heart disease. However, there are other factors that can also raise your risk for atrial fibrillation.

Typically, the electrical signals that make the heart pump start in the sinoatrial node, a special area of the right atrium, or the upper right chamber of the heart. The signal makes both the right atrium and the left atrium contract. That action pumps blood to the ventricles, or lower chambers. The electrical signal then travels further down the heart, signaling the ventricles to contract. In atrial fibrillation, unusual electrical signals in the upper chambers interrupt the typical process. Then, the upper chambers of the heart do not contract at a regular pace.

Illustration of atrial fibrillation
This image shows the electrical system of the heart during atrial fibrillation and includes a picture of an electrocardiogram in the upper right corner showing the irregular electrical impulses that are measured during A-fib. Medical Illustration Copyright © 2022 Nucleus Medical Media, All rights reserved

Changes in heart tissue

Aging, heart disease, infection, genetics, or other factors change heart tissue and can keep the heart cells from working together to contract in rhythm. This can happen because of fibrosis, inflammation, thinning or thickening of the heart walls, less blood flow to the heart, or a buildup of protein, cells, or minerals in heart tissue.

Changes in electrical signaling

Usually, a “trigger” heartbeat sets off atrial fibrillation. Electrical signals from this trigger beat may cause the heart to keep beating slower or faster than usual. Sometimes, electrical signals start an abnormal loop, telling the heart to contract over and over. This can create the fast, irregular heartbeat that defines atrial fibrillation.

Changes in the heart’s electrical signaling can be caused by differences in the structure of the heart, heartbeats that happen early or too often, typical heart rate adjustments, patches of heart tissue that conduct the signal quickly or slowly, or repeated stimulation of specific areas of the heart.

What raises the risk of atrial fibrillation?

Age, family history and genetics, lifestyle, heart disease or other medical conditions, race, and a surgical history can all raise your risk of developing the structural and electrical issues that lead to atrial fibrillation. Even in a healthy heart, a fast or slow heart rate — from exercising or sleeping, for example — can trigger atrial fibrillation.


The risk of atrial fibrillation increases as you age, especially after age 65. Atrial fibrillation is rare in children, but it does occur, especially in boys and in children who have obesity.

Family history and genetics

If someone in your family has had atrial fibrillation, you have a higher risk of developing atrial fibrillation, too. Scientists have found some gene with mutations that raise the risk of atrial fibrillation. Some of these genes influence fetal organ development or heart cell ion channels.

Sometimes these genetic patterns are also linked to heart disease. Some genetic factors may raise the risk of atrial fibrillation in combination with such factors as age, weight, or sex.

Lifestyle factors

Some lifestyle choices can raise or lower your risk of atrial fibrillation.

  • Alcohol consumption in large amounts, especially binge drinking, raises your risk of atrial fibrillation. Even modest amounts of alcohol can trigger atrial fibrillation in some people.
  • Illegal drugs, such as cocaine and other street drugs, can trigger atrial fibrillation or make it worse.
  • Physical activity, for example, participating in endurance sports or physically working hard, may lead to higher risk of atrial fibrillation for some people, especially competitive athletes and men. At the same time, moderate physical activity can have a protective effect. Physical fitness appears to be linked to a lower risk of atrial fibrillation.
  • Smoking increases the risk of atrial fibrillation, according to many studies. The risk appears to be higher the longer you smoke and decreases if you quit. Exposure to secondhand smoke, even in the womb, can increase a child’s risk of developing atrial fibrillation.
  • Stressful situations, panic disorders, and other types of emotional stress may be linked to a higher risk of atrial fibrillation.

Other medical conditions

Many other medical conditions can increase your risk of atrial fibrillation, especially heart problems. As you age, having more than one condition may increase your risk. Conditions that raise the risk of atrial fibrillation include:


In the United States, atrial fibrillation is more common among white Americans than among African Americans, Hispanic Americans, or Asian Americans. Although people of European ancestry are more likely to develop the condition, Black and African American people with atrial fibrillation are more likely to have serious complications such as stroke, heart failure, or heart disease where blood flow (and oxygen flow) is reduced.


You may be at risk of atrial fibrillation in the early days and weeks after surgery on your heart, lungs, or esophagus. Heart surgery to correct a congenital heart defect can also raise the risk of atrial fibrillation. This risk remains even years after a childhood surgery. It is also a risk if someone has surgery as an adult to correct a lifelong condition.

Can you prevent atrial fibrillation?

  • To help you lower your risk of atrial fibrillation, your doctor may recommend certain heart-healthy lifestyle changes, including aiming for a healthy weight, being physically active, controlling your blood sugar, limiting alcohol, lowering your blood pressure, managing stress, and quitting smoking.
  • Some illegal drugs, such as cocaine, can trigger atrial fibrillation or make it worse. If you use illegal or street drugs, ask your provider how to get help to stop. You can also call the Substance Abuse and Mental Health Services Administration’s National Helpline at 1-800-662-HELP.
  • If you are having heart surgery, your medical team will monitor you. To prevent arrhythmia, your doctor may recommend antiarrhythmic medicine or treatment to maintain or supplement electrolytes levels during or after the procedure.
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Your Guide to a Healthy Heart

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