Atrial Fibrillation
Atrial Fibrillation

Atrial Fibrillation Diagnosis

A healthcare provider will diagnose atrial fibrillation based on your medical and family history, a physical exam, the results from an electrocardiogram (EKG), and possibly other tests and procedures. If you have atrial fibrillation, your provider will also look for any disease that may be causing it and assess your risk of developing dangerous blood clots. This will help in planning the best way to treat you.

Screening methods

Screening, or checking for symptoms and risk factors, helps healthcare providers decide whether diagnostic testing is needed. Your healthcare provider may screen you for atrial fibrillation only when you have risk factors. However, they may also check for symptoms of atrial fibrillation as part of your regular medical care. Your provider may also recommend healthy lifestyle changes to help you lower your risk of developing atrial fibrillation. Screening steps may be part of your regular care if you are 65 or older or if you have other risk factors. Your provider may check your pulse for an irregular speed or unusual heart rhythm even if you have no symptoms.

  • If you had a stroke and there is no clear cause, your provider may recommend screening for atrial fibrillation with a Holter or event monitor or a loop recorder.
  • Several devices are now available to detect and record your heart’s rhythm similar to the way an EKG does. These devices may also allow the data to be sent to your healthcare provider by email.
Fact Sheet

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Learn more about how healthy lifestyle changes can help prevent heart disease.

Medical history

Your provider will ask about your eating and physical activity habits, family history, and other risk factors for atrial fibrillation and heart disease. You may also be asked whether you have any other symptoms. This information can help your provider determine whether you have other conditions that may be causing you to have atrial fibrillation.

Physical examination

Your provider will do a complete physical examination, paying close attention to your heart and lungs. During this examination, they will:

  • Check for signs of too much thyroid hormone, such as a thyroid gland that is larger than normal
  • Check for swelling in your legs, ankles, or feet, which could be a sign of heart failure or a heart that is larger than normal and doesn’t pump blood properly
  • Check your pulse to find out how fast your heart is beating
  • Listen to the rhythm of your heartbeat
  • Listen to your lungs to check for signs of heart failure or infection
  • Measure your blood pressure, height, and weight

Diagnostic tests

To diagnose atrial fibrillation, your provider will likely do one or more heart or blood tests.

  • Electrocardiograms, or EKGs, record your heart’s electrical activity. Data from your pacemaker or implanted defibrillator, if you have one, may also be helpful. If the diagnosis is unclear from the EKG or if more information is needed, your provider may order additional testing.
  • Blood tests check the level of substances in the blood, such as potassium and thyroid hormone. This can help find the cause of your atrial fibrillation and show how well your liver and kidneys are working, which can help your healthcare provider decide which medicines are most appropriate.
  • Echocardiography (ultrasound) looks at the heart valves, chamber sizes and heart pumping function. This test may show heart valve diseases, areas of heart muscle that are not pumping normally, and any previous injury to the heart muscle caused by poor blood flow. It may also identify harmful blood clots in the heart’s chambers.
  • Cardiac magnetic resonance imaging (MRI) and other imaging tests may be performed in some cases so your provider can see the structure of the left upper chamber of the heart (left atrium) and how well it is working. This information can help determine if there is a risk for complications from atrial fibrillation. The images can also help identify other causes of atrial fibrillation and allow providers to create a treatment plan based on your specific condition.

Other tests

Your healthcare provider may order other tests to record abnormal heart rhythms that occur under specific conditions or outside of the clinic, confirm whether you have atrial fibrillation or another arrhythmia, and find the best treatment.

  • Chest X-rays look for signs of complications from atrial fibrillation, such as fluid buildup in the lungs or a heart that is larger than normal.
  • An electrophysiology studyrecords your heart’s electrical signals if your provider wants more detail about what is causing a particular EKG reading or to distinguish among possible types of arrhythmias.
  • Holter and event monitors record your heart’s electrical activity over long periods of time while you do normal, day-to-day activities. These portable EKG monitors can help assess the cause of symptoms, like palpitations or dizziness, that happen outside the healthcare provider’s office. Most portable monitors will send data directly to your provider.
  • A loop recorderrecords the heart’s electrical activity. Some loop recorder models are worn outside the body, and some require minor surgery to place the device under the skin in the chest area. Implanted devices can record data for months and are used to detect patterns in abnormal heart rhythms that do not happen very often.
  • sleep study can determine whether sleep disorders such as sleep apnea might be causing your symptoms.
  • stress test or exercise stress test studies changes in your heart’s activity that occur when your heart rate increases after exercise. If you cannot exercise, your provider may give you medicine to make your heart work hard and beat fast.
  • Transesophageal echocardiography checks for blood clots that may be forming in the heart’s upper chambers because of atrial fibrillation. It uses sound waves to take pictures of your heart through the esophagus.
  • A walking test measures your heart activity while you walk for 6 minutes. This can help determine how well your body can control your heart rate under normal circumstances.
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