How is atrial fibrillation diagnosed?

The most commonly used tests to diagnose atrial fibrillation include:

  • Electrocardiogram (ECG or EKG): The ECG draws a picture on graph paper of the electrical impulses traveling through the heart muscle. An EKG provides an electrical “snapshot” of the heart.
  • For people who have symptoms that come and go, a special monitor may need to be used to "capture" the arrhythmia.
    • Holter monitor: A small external recorder is worn over a short period of time, usually one to three days. Electrodes (sticky patches) are placed on the skin of your chest. Wires are attached from the electrodes to the monitor. The electrical impulses are continuously recorded and stored in the monitor. After the monitor is removed, a technician uses a computer to analyze the data to evaluate the heart’s rhythm.
    • Portable event monitor: A monitor that is worn for about a month for patients who have less frequent irregular heartbeat episodes and symptoms. Electrodes (sticky patches) are placed on the skin of your chest. Wires are attached from the electrodes to the monitor. The patient presses a button to activate the monitor when symptoms occur. The device records the electrical activity of the heart for several seconds. The patient then transmits the device’s recorded information over a telephone line to the doctor’s office for evaluation. The portable event monitor is very useful in determining what heart rhythm is causing your symptoms.
    • Transtelephonic monitor: When you develop symptoms of atrial fibrillation, a strip of your current heart rhythm can be transmitted to your doctor’s office over the telephone, using a monitor with two bracelets or by placing the monitor against your chest wall.

These monitoring devices help your doctor determine if an irregular heart rhythm (arrhythmia) is causing your symptoms. Learn more about diagnostic tests.

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