Definition

Atrial fibrillation is an abnormal heart rhythm. The heart’s electrical system normally sends regularly spaced signals. These signals tell the heart muscle to contract or beat.

The heart has two upper chambers called atria. It also has two lower chambers called ventricles. Each signal starts in the atria and travels to the rest of the heart. In atrial fibrillation, the electrical signals from the atria are fast and irregular. The atria shake instead of contract. Some signals do not reach the ventricles and the ventricles continue pumping. This pumping is usually irregular and sometimes rapid. This rhythm can reduce the heart’s ability to pump blood out to the body. Blood left in the heart chambers can form clots. These clots may sometimes break away and travel to the brain. This can cause stroke.

Causes

In most cases, atrial fibrillation is due to an existing heart condition. Atrial fibrillation can also occur in people who do not have structural heart problems. A thyroid disorder or other condition may cause the abnormal rhythm. The cause of atrial fibrillation is sometimes unknown.

Risk Factors

Atrial fibrillation is more common in men and in people aged 55 years and older. Other factors that may increase your chance of atrial fibrillation include:

• Family history of atrial fibrillation
• Cardiovascular diseases, such as high blood pressure, coronary artery disease, heart failure, heart attack, heart valve disease, endocarditis, cardiomyopathy, congenital heart disease, prior episode of atrial fibrillation
• Lung diseases, such as emphysema, asthma, blood clots in the lungs
• Chronic conditions, such as overactive thyroid, diabetes
• Prescription medications to treat chronic conditions, such as opioids for pain relief
• Lifestyle factors:
  • Smoking
  • Excessive alcohol use
  • Excessive use of stimulants like caffeine
  • Physical and/or emotional stress
• Receiving general anesthesia

Symptoms

Symptoms can be mild to severe. This depends on your heart function and overall health. Some people may not notice any symptoms.

In those that have them, symptoms may include:

• Irregular or rapid pulse or heart beat
• Racing feeling in the chest
• A pounding feeling in the chest
• Lightheadedness, which can lead to fainting
• Sweating
• Pain or pressure in the chest
• Shortness of breath
• Fatigue or weakness
• Unable to exercise

Diagnosis

The doctor will:

• Ask about your symptoms and medical history
• Perform a physical exam
• Listen to your heart with a stethoscope

You doctor will order blood tests to help diagnose the problem.

• Imaging tests may include:
  • Chest x-ray
  • Echocardiogram
  • Coronary angiography
• Electrical activity tests of your heart can be done with:
  • Electrocardiogram (EKG)
  • Holter monitor

Treatment

The goals of treatment are to:

• Return your heart to a regular rhythm.
• Keep your heart rate close to normal—In general, your resting rate should be between 60-80 beats per minute. It should be 90-115 beats per minute during moderate exercise.
• Prevent blood clots from forming.

Your doctor may find another condition that is causing atrial fibrillation. This condition may be treated. In some cases, heart rhythm problems return to normal without treatment.

Treatment options include:

Prevention

To help reduce your chance of atrial fibrillation:

• Avoid known triggers
• Exercise regularly within your doctor’s guidelines
• Control other chronic conditions, such as heart disease or diabetes

Heart Rhythm Society http://www.hrsonline.org/

Heart and Stroke Foundation http://www.heartandstroke.com

Atrial fibrillation. CardioSmart website. Available at:
http://cardiosmart.org/HeartDisease/CTT.aspx?id=222
Accessed November 9, 2012.

Cardioversion. Cleveland Clinic website. Available at:
http://my.clevelandclinic.org/services/heart/services/cversion
Updated December 28, 2011. Accessed November 9, 2012.

Explore atrial fibrillation. National Heart Lung and Blood Institute website. Available at:
http://www.nhlbi.nih.gov/health/health-topics/topics/af
Updated July 1, 2011. Accessed November 9, 2012.

12/13/2010 DynaMed’s Systematic Literature Surveillance
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Lubitz SA, Yin X, et al. Association between familial atrial fibrillation and risk of new-onset atrial fibrillation. JAMA. 2010;304(20):2263-2269.

5/11/2012 DynaMed’s Systematic Literature Surveillance
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Osbak PS, Mourier M, et al. A randomized study of the effects of exercise training on patients with atrial fibrillation. Am Heart J. 2011;162(6):1080-1087.

1/2/2014 DynaMed’s Systematic Literature Surveillance
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Abed HS, Wittert GA, et al. Effect of weight reduction and cardiometabolic risk factor management on symptom burden and severity in patients with atrial fibrillation: A randomized clinical trial. JAMA. 2013;310(19):2050-2060.

7/1/2015 DynaMed’s Systematic Literature Surveillance
http://www.ebscohost.com/dynamed:
Qureshi WT, O’Neal WT, Khodneva Y, et al. Association between opioid use and atrial fibrillation: The Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. JAMA Intern Med. 2015;175(6):1058-1060.