An electrophysiology (EP) study is a series of tests that examine the heart's electrical activity. It's also called an invasive cardiac electrophysiology test.

The heart's electrical system produces signals that control the timing of the heartbeats. During an EP study, heart doctors, called cardiologists, can create a very detailed map of how these signals move between each heartbeat.

An EP study can help determine the cause of irregular heart rhythms, called arrhythmias. Sometimes it's done to predict the risk of sudden cardiac death.

An EP study is done in a hospital by doctors with special training in heart rhythm disorders. These healthcare professionals are called electrophysiologists.

Why it's done

An EP study gives your healthcare team a very detailed look at how electrical signals move through the heart. You may need an EP study if:

  • You have an irregular heart rhythm, called an arrhythmia. If you have an irregular or fast heartbeat, such as supraventricular tachycardia (SVT) or any other type of tachycardia, an EP study can help determine the best treatment.
  • You fainted. If you had a sudden loss of consciousness, an EP study can help determine the cause.
  • You're at risk of sudden cardiac death. If you have certain heart conditions, an EP study can help determine your risk of sudden cardiac death.
  • You need a treatment called cardiac ablation. Cardiac ablation uses heat or cold energy to correct irregular heart rhythms. An EP study is always done before cardiac ablation to find the area of the irregular heart rhythm. If you're having heart surgery, you may have cardiac ablation and an EP study on the same day.


As with many tests and procedures, an EP study has risks. Some can be serious. Possible EP study risks include:

  • Bleeding or infection.
  • Bleeding around the heart caused by damage to the heart tissue.
  • Damage to the heart valves or blood vessels.
  • Damage to the heart's electrical system, which could require a pacemaker to correct.
  • Blood clots in the legs or lungs.
  • Heart attack.
  • Stroke.
  • Death, rarely.

Talk to a healthcare professional about the benefits and risks of an EP study to learn if this procedure is right for you.

How you prepare

Do not eat or drink anything after midnight on the day of an EP study. If you take any medicines, ask your care team if you should continue taking them before your test.

Your care team tells you if you need to follow any other special instructions before or after your EP study.

What you can expect


An EP study is done in the hospital. An IV line is inserted in the hand or arm. Sticky patches with sensors on them, called electrodes, are placed on the chest to check the heartbeat during the test.

A member of your care team shaves any hair from the area where a tube, called a catheter, will be placed to do the surgery. Usually this is in the groin area.

Before the procedure starts, you typically get medicine called a sedative to relax you. A combination of medicines may be used to put you in a sleep-like state. This is called general anesthesia.


During an EP study, long, thin tubes called catheters are placed in three or more heart areas.

The heart doctor inserts the tubes into a blood vessel. The doctor guides the tubes to the heart, often using moving X-ray images as a guide. Sensors on the tips of the catheters send electrical signals to the heart and record the heart's electrical activity.

Several different tests can be done during an EP study. Which tests you have depend on your specific condition and your overall health. During an EP study, a heart doctor can:

  • Measure the electrical signals at different area in the heart. Sensors at the tip of the catheters record the heart's initial electrical activity at different locations. This test is called an intracardiac electrogram. It shows how electrical signals are moving through the heart.
  • Send signals that cause the heart to beat faster or slower. Electrical signals are sent through the catheters to different areas of the heart to speed up or slow down the heartbeat. Doing so can show if you have extra electrical signals causing an arrhythmia, and where those signals are coming from.
  • Give medicines to see how they affect the heartbeat. Certain medicines may be delivered through the catheter directly into the heart to block or slow electrical activity in a certain area. The heart's reaction to the medicine provides more clues about your condition.
  • Map the heart. Also called cardiac mapping, this is the process of determining the best location to apply cardiac ablation to treat an irregular heartbeat.
  • Do a treatment called cardiac ablation. If a health care provider determines that cardiac ablation is appropriate, the treatment may be done during the EP study. Cardiac ablation uses special catheters to apply heat or cold energy to areas of the heart. The energy creates scar tissue that blocks irregular electrical signals to restore a typical heart rhythm.

An EP study doesn't hurt, but you may feel uncomfortable as your heartbeat speeds up or slows down. Tell your care team if you feel any pain.

An EP study can take 1 to 4 hours. Your test may last longer if you also have cardiac ablation.


Following your EP study, you'll be moved to a recovery area to rest quietly for 4 to 6 hours. Your care team checks your heartbeat and blood pressure to watch for complications.

Most people go home the same day. Plan to have someone else drive you home after your test and to relax for the rest of the day. You may feel some soreness for a few days where the catheters were inserted.


Your healthcare team shares the results of your EP study with you after the test, usually at a follow-up appointment. Treatment recommendations may be made based on the results.

Clinical trials

Explore Mayo Clinic studies of tests and procedures to help prevent, detect, treat or manage conditions.

Jan. 04, 2024
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