Tests and Procedures
EP study

Updated: 3/27/2018


An electrophysiology (EP) study is a test used to understand and map the electrical activity within your heart.

An EP study may be recommended in people with heart rhythm problems (arrhythmias) and other heart problems to understand the exact cause and determine which treatment is most likely to be effective. Doctors also use EP studies to predict the risk of sudden cardiac death in certain situations.

An EP study involves placing diagnostic catheters within your heart and running specialized tests to map the electrical currents. EP studies are done in the hospital and carry a small risk of serious complications.

Why it's done

An EP study is a test to understand the way electrical signals move through your heart to make it beat. An EP study is used in people whose bodies produce ineffective or chaotic electrical signals that cause the heart to beat incorrectly. An EP study can also be used to predict the risk of sudden cardiac death.

Your doctor may recommend an EP study if you:

  • Have an abnormal heart rhythm (arrhythmia). If you've been diagnosed with an arrhythmia, such as atrial fibrillation, atrial flutter, tachycardia, ventricular tachycardia or supraventricular tachycardia, your doctor may recommend an EP study to better understand how electrical signals move in your heart and how best to treat your condition.
  • Are undergoing cardiac ablation. An EP study is done at the beginning of a cardiac ablation procedure for arrhythmia. Cardiac ablation uses heat or cold energy to create scar tissue in the heart to block erratic electrical signals.
  • Experience a temporary loss of consciousness (syncope). People who experience syncope may undergo an EP study to understand the cause.
  • Have a risk of sudden cardiac death. If you have a heart condition that increases your risk of sudden cardiac death, an EP study may help your doctor better understand your risk.
  • Are undergoing heart surgery. If you're preparing for a heart operation in which cardiac ablation may be performed at the same time, your doctor may recommend an EP study.


An EP study carries a risk of complications, including:

  • Bleeding or infection at the site where your catheter was inserted
  • Damage to your blood vessels where the catheter may have scraped as it traveled to your heart
  • Puncture of your heart
  • Damage to your heart valves
  • Damage to your heart's electrical system, which could worsen your arrhythmia and require a pacemaker to correct
  • Blood clots in your legs or lungs (venous thromboembolism)
  • Stroke or heart attack
  • Death in rare cases

Discuss the risks and benefits of an EP study with your doctor to understand if this procedure is right for you.

How you prepare

Your doctor will evaluate you and may order several tests to evaluate your heart condition. Your doctor will discuss with you the risks and benefits of an EP study.

You'll need to stop eating and drinking the night before your test. If you take any medications, ask your doctor if you should continue taking them before your test.

Your doctor will let you know if you need to follow any other special instructions before or after your EP study. In some cases, you'll be instructed to stop taking medications to treat a heart arrhythmia several days before your test.

If you have an implanted heart device, such as a pacemaker or implantable cardioverter-defibrillator, talk to your doctor to see if you need to take any special precautions.

What you can expect

During an EP study

An EP study is performed in the hospital. Before your procedure begins, a specialist will insert an intravenous line into your forearm or hand, and you'll be given a sedative to help you relax. In some situations, general anesthesia may be used instead to place you in a sleep-like state.

After the sedative takes effect, your doctor or another specialist will numb a small area near a vein in your groin, neck or forearm. Your doctor will insert a needle into the vein and place a tube (sheath) through the needle.

Your doctor will thread catheters through the sheath and guide them to several places within your heart. Your doctor may inject dye into the catheter, which helps your care team see your blood vessels and heart using X-ray imaging. The catheters have electrodes at the tips that can be used to send electrical impulses to your heart and record your heart's electrical activity.

Several techniques may be used during an EP study, including:

  • Taking a baseline measurement of the electrical activity in your heart. Your doctor will begin by placing a diagnostic catheter in various locations in your heart and recording the activity (intracardiac electrogram). The results from each part of your heart give your doctor a better idea of how the electrical signals are moving through your heart.
  • Using an electrode to cause an abnormal heart rhythm. Your doctor may use a catheter that can emit electricity to cause your heart to beat faster or slower and cause an arrhythmia. Your heart's reaction to the stimulus is recorded. By placing the electrode in different areas of your heart, your doctor can determine if you have extra electrical signals in your heart and where those signals are coming from.
  • Using medicines that affect heart function. Certain medications may be infused into your heart to block or slow electrical activity in a certain area of your heart. Your heart's reaction to the medication gives your doctor more clues about your condition.
  • Mapping the heart in preparation for cardiac ablation. Cardiac mapping is the process of determining the best location to apply cardiac ablation to treat arrhythmia. Imaging tests are used to create a map of your heart that's used during the procedure.

    If your doctor determines that cardiac ablation is appropriate, he or she may continue with that procedure during your EP study. Cardiac ablation involves using special catheters to apply heat or cold energy to areas of your heart. The energy creates scar tissue that blocks the erratic electrical signals in your heart.

Which tests you undergo during an EP study will depend on your condition and the reason for your test. An EP study can take one to four hours. Your test may last longer if you're also undergoing cardiac ablation.

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

After an EP study

Following your EP study, you'll be moved to a recovery area to rest quietly for four to six hours to prevent bleeding at your catheter site. Your heartbeat and blood pressure will be monitored continuously to check for complications.

Most people go home the same day. Plan to have someone else drive you home after your test and to take it easy for the rest of the day. It's normal to feel some soreness for a few days where the catheter was inserted.


Your doctor will share the results of your EP study with you after the test — most often in a follow-up appointment. He or she may also make recommendations for treatment based on the results.

Content from Mayo Clinic