Abnormalities or damage to the heart's structure are the most common cause of atrial fibrillation. Possible causes of atrial fibrillation include:
High blood pressure
Coronary artery disease
Abnormal heart valves
Heart defects you're born with (congenital)
An overactive thyroid gland or other metabolic imbalance
Exposure to stimulants, such as medications, caffeine, tobacco or alcohol
Sick sinus syndrome — improper functioning of the heart's natural pacemaker
Previous heart surgery
Stress due to pneumonia, surgery or other illnesses
However, some people who have atrial fibrillation don't have any heart defects or damage, a condition called lone atrial fibrillation. In lone atrial fibrillation, the cause is often unclear, and serious complications are rare.
Certain factors may increase your risk of developing atrial fibrillation.
Age. The older you are, the greater your risk of developing atrial fibrillation.
Heart disease. Anyone with heart disease — such as heart valve problems, congenital heart disease, congestive heart failure, coronary artery disease, or a history of heart attack or heart surgery — has an increased risk of atrial fibrillation.
High blood pressure. Having high blood pressure, especially if it's not well-controlled with lifestyle changes or medications, can increase your risk of atrial fibrillation.
Other chronic conditions. People with certain chronic conditions such as thyroid problems, sleep apnea, metabolic syndrome, diabetes, chronic kidney disease or lung disease have an increased risk of atrial fibrillation.
Drinking alcohol. For some people, drinking alcohol can trigger an episode of atrial fibrillation. Binge drinking may put you at an even higher risk.
Obesity. People who are obese are at higher risk of developing atrial fibrillation.
Family history. An increased risk of atrial fibrillation is present in some families.