Electrophysiological (EP) study

Doctor and monitors

An electrophysiological (EP) study is a test which looks at your heart's electrical activity in more detail.

It’s used to diagnose and treat a wide variety of abnormal heart rhythms.

What happens during an EP study?


An EP study is carried out in a cath lab by a specialist cardiac doctor called an electrophysiologist. It usually takes about 2-3 hours, but can take longer. You’ll be asked not to eat or drink anything for a few hours beforehand.

  • Thin flexible tubes called catheters are inserted into a vein, usually in the groin. You’ll have a local anaesthetic injection to numb the area where the catheters are put in. You may also be given a sedative to help you relax during the procedure.
  • The catheters are passed up to the heart. This can induce an arrhythmia (an abnormal heart rhythm). 
  • You may feel lightheaded or like you’re having palpitations. You may also feel a sensation or discomfort in your chest. You should tell the staff if you experience any symptoms. 

What happens after an EP study? 

When the test is over, the catheters are removed. Sometimes there may be a small amount of bleeding when they’re taken out. A nurse or doctor will press on the area to stop any bleeding.

You will be asked to stay in bed for a few hours after the test but most people can go home after this.

It’s normal to feel tired afterwards, but you should feel back to normal within a few days.

You may notice that you can feel your heart beating afterwards, or you may feel extra or missed beats. This is common and will usually settle down over time.

What can an EP study show?

An EP study can stimulate and diagnose abnormal heart rhythms and identify which areas of your heart are affected.

If the cause of your abnormal heart rhythm is found, the doctor will sometimes proceed to treat the problem by doing a catheter ablation. This treatment uses either heat (radio-frequency ablation) or freezing (cryogenic ablation) to destroy the areas inside the heart which are causing the abnormal rhythm and therefore relieve the symptoms. This may be done at the same time as the EP study.  

What are the risks of having an EP study?

Complications when you have an EP study are rare. Your doctor will explain this to you before you give your consent to have the test.

If there’s bleeding from the area where the catheter was placed, you might develop a collection of blood under the skin, called a haematoma. It can be uncomfortable and will cause bruising, but should settle after a few days. However, contact your doctor if you have any concerns.

There is a small risk of damage to the heart's normal electrical pathways. If this happens, you may need to be fitted with a pacemaker.

Want to find out more?

Tests booklet

Tests for heart conditions booklet

This booklet describes the special tests that are commonly used to help diagnose heart diseases.

Some of the tests are also used to assess the current condition of people who have already been diagnosed with heart disease.