Atrial fibrillation (AF or afib) happens when your heart’s pumping becomes fast or irregular because of changes in heart tissue or a malfunction in electrical signaling. (1)

Some causes or contributing factors behind atrial fibrillation are medical conditions beyond your control, while others are related to your lifestyle. (2)

“There are many different causes of atrial fibrillation,” notes Marc Gillinov, MD, the surgical director of the Center for Atrial Fibrillation at the Cleveland Clinic and the author of the book Heart 411.

Most people with afib have an underlying heart condition that leads to the disorder. But in at least 10 percent of cases, an underlying cause is never identified, according to the Cleveland Clinic. (3)

Heart Conditions Are Risk Factors

The biggest risk factors for afib are older age and underlying heart disease, such as coronary artery disease or heart valve disease. Your risk is especially high after age 65. (1)

Almost any heart condition can increase your risk for abnormal rhythm and damage your heart’s structure.

Some of the most common heart conditions that can lead to atrial fibrillation include:

High blood pressure (hypertension) When your blood pressure — the force of blood in your arteries — is too high, your heart has to work harder than normal, which can lead to dysfunction.

Heart valve disease When your heart valves don’t work properly, your heart can have trouble pumping blood.

Congenital heart defects Being born with a heart abnormality may mean you'll eventually develop atrial fibrillation.

Heart attack When blood flow to your heart becomes blocked, your heart muscle can suffer damage.

Heart surgery Afib can develop right after heart surgery or as a later complication. (1,3)

Other Health Conditions Can Also Raise Your Risk

Some other health conditions can raise your risk of afib, including:

Sleep apnea This condition is marked by pauses in your breathing during sleep.

Diabetes When there is too much glucose (sugar) in your blood, heart damage or neurological damage can occur.

Hyperthyroidism This condition occurs when your thyroid gland makes too much thyroid hormone, which can cause neurological disruption.

Emphysema This is a form of chronic obstructive pulmonary disease (COPD) that damages the air sacs in your lungs and makes it hard to breathe.

Pulmonary embolism This happens when a blood clot, usually in your leg, breaks off and travels to block an artery leading to your lungs. (1,3)

“The numbers of people with sleep apnea, diabetes, and high blood pressure are increasing and contributing to more cases of afib,” says Dr. Gillinov. (4)

Uncontrollable Risk Factors

A few personal and demographic traits can increase your risk of afib as well. They include:

Older age The single biggest risk factor is being older. “The exact reason is not known, but it may be due to progressive scarring of atrial tissue,” says Gillinov.

The odds of developing afib are notably higher after age 65, when about 9 percent of people have the condition, according to the Centers for Disease Control and Prevention (CDC). (2)

Family history People with an immediate family member — a parent or a sibling — with the condition are at higher risk. (5)

European ancestry White people are more likely than other racial or ethnic groups to develop afib. (2)

Controllable Risk Factors

Certain lifestyle factors make it more likely that you’ll develop afib. These factors can be managed by making lifestyle changes. They include:

Excessive alcohol use Heavy use of alcohol, and in particular binge drinking (five drinks in two hours for men, or four drinks for women), can trigger afib.

Even small amounts of alcohol can trigger the condition in some people, according to the National Heart, Lung, and Blood Institute.

Illegal drug use Certain street drugs, including cocaine, can trigger afib or make it worse.

Physical exertion Competitive athletes and people who exert themselves at work are at higher risk for afib, while moderate physical activity and being physically fit are associated with a lower risk.

Smoking The longer you smoke or are exposed to secondhand smoke, the higher your risk for afib. This risk can be reduced by quitting.

Stress Stressful situations and emotional distress can raise your risk for the condition. (1)

Complications of the Condition

Afib can lead to a number of serious complications.

Even though white Americans are at higher risk for the condition than other racial or ethnic groups, African-Americans are at higher risk for complications of the condition. (1)

Potential complications of atrial fibrillation include:

Blood clots Afib may cause your heart not to pump blood adequately, so that blood pools and forms clots in your heart.

Blood clots can break off and travel to different areas of your body, potentially blocking blood flow and causing serious tissue damage.

Stroke A stroke happens when a blot clot breaks off and travels to your head, blocking off blood flow to your brain.

In some people with afib, the condition has no symptoms, and a stroke is the first sign that you have it.

If you have afib your risk of a stroke is higher if you’re older or if you’re a woman.

Heart attack A heart attack happens when blood flow to your heart is blocked, usually by a clot that breaks off from another area of your body.

Women and African Americans with afib are at higher risk for a heart attack.

Heart failure When your heart is beating too quickly and unevenly, it may not pump blood adequately throughout your body.

If you already have heart failure, afib may make your symptoms worse.

Sudden cardiac arrest Afib raises the risk that your heart will suddenly stop beating, especially if you have another heart condition that raises this risk.

Cognitive impairment Research suggests that people with afib are at higher risk for cognitive issues and dementia, possibly because of reduced blood flow to the brain. (1,6)