Electrophysiology (EP) Study

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What is Electrophysiology (EP) Study?

An Electrophysiological (EP) Study helps assess the heart’s electrical system and to detect any abnormalities in its conduction system that could be causing heart rhythm disorders. It is commonly used to diagnose abnormal heartbeats or arrhythmias and involves the insertion of catheters or wire electrodes to measure the heart’s electrical activity. 

An EP study is carried out by cardiologists who specialise in heart rhythm disorders and helps them map the pathways of complex arrhythmias to determine the best course of action when a catheter ablation is done.

What is an EP Study for?

Your cardiologist would generally recommend an EP study to diagnose heart arrhythmias or to determine your risk of developing a heart rhythm disorder. They may also carry out an EP study to:

  • Discern your risk of cardiac arrest.
  • Discern what treatment options would be best for you.
  • Assess the effectiveness of your medication and treatments during follow-ups.
How do I prepare for an EP Study?

In order to get accurate results, your cardiologist will advise you on what medications to temporarily stop before the procedure. Additionally, you can prepare by:

  • Following your cardiologist’s instructions on the types of food you should avoid before your test. You may be asked to fast 6 – 8 hours prior to your test to prevent nausea.
  • Asking your friend or family to bring you to and fro the hospital.
  • Preparing a list of medications you normally take. 
  • Eating regularly the evening before the procedure.
What happens during an EP Study?

Rest assured, the procedure is generally painless and will take about 1 – 4 hours. It is important to stay calm and relaxed. Let your cardiologist or the nurses know if you feel any discomfort. 

  1. You will be placed on an X-ray table and electrodes will be attached to your chest to monitor your heart rate, while a blood pressure cuff will be attached to your arm to monitor your blood pressure. 
  2. A local anaesthetic will be administered to ensure a painless and comfortable procedure. A sedative may also be given intravenously.
  3. Catheters are then inserted through a vein via your groin or neck and guided towards the heart. This will be closely monitored on a screen.

Once the electrode reaches the heart:

  1. Your cardiologist will take a baseline measurement of the heart’s electrical system (intracardiac electrogram).
  2. Electrical signals may be sent to various areas of the heart to assess how it responds to electrical stimulation, making it beat faster or slower to detect abnormal heart rhythms. 
  3. Medication may be used to stimulate an arrhythmia and see how the heart responds.
  4. Cardiac mapping is done to determine the best form of treatment and – if a catheter ablation will be carried out – the best area to do so.

After the procedure:

  1. You will be asked to rest for 4 – 6 hours. 
  2. If you feel pain, discomfort or bleeding, please let your cardiologist or attending nurse know immediately. 
  3. Your cardiologist will share their findings with you and let you know if catheter ablation is necessary, or prescribe other forms of treatment.
Will I be awake during an EP Study?

You will be awake during the procedure. However, a sedative will be administered to keep you calm, if required.


An EP Study is essential in understanding the heart’s electrical function and allows your cardiologist to examine abnormalities in the heart’s rhythm under controlled conditions. After the procedure, getting ample rest is crucial – try to limit physical activity for at least 24 hours.

How can we help you?

We offer consultation for a comprehensive range of cardiac diagnostic tests and treatment plans.

Dr Joshua Loh

Senior Consultant Interventional Cardiologist

Medical Director at Capital Heart Centre, Dr Joshua Loh has more than 15 years of experience in the field of cardiology.

He has extensive experience in the treatment of complex coronary and interventional procedures.