Cardiac Electrophysiology Studies
(EP Study)


What is a Cardiac Electrophysiology Study (EP Study)

Cardiac Electrophysiology Studies (EP Study) are the study of normal and abnormal electrical behaviour of the heart. They are used to evaluate your heart’s electrical system and to check for abnormal heart rhythms (arrhythmias). 

An EP Study is performed by a Cardiac Electrophysiologist (EP). All EPs are cardiologists, who have advanced training and focus on testing for and treating problems specifically caused by irregular heart rhythms, also known as arrhythmias. 

An EP may perform a Cardiac Electrophysiology Study for a variety of reasons, including the following:

  • to determine the cause of a fast heart rhythm (supraventricular tachycardia or SVT), 
  • to investigate the cause of unexplained blackouts, or
  • to determine if there is an induceable ventricular tachycardia rhythm that may be suitable for an implanted cardiac defibrillator device.

The EP study helps your EP to determine an appropriate treatment for the heart rhythm problem – for example, medications, catheter ablation, pacemaker or implantable cardiac defibrillator. 

How to prepare for an EP Study


Most medication should be continued as usual, but some may interfere with the operation. Your cardiologist will inform you of the medication you should stop. 

As a guide, the following types of medication may require special instruction from your cardiologist:

  • Aspirin (or any related products);
  • Blood thinners (Warfarin, Heparin);
  • Arthritis medication;
  • Pain medication;
  • Anti-inflammatory medication;
  • Insulin.
  • Don’t forget to mention any homeopathic or herbal remedies you are taking, as these can have interactions and side effects too.


In most cases you will be required to fast (no food or drink) for six to eight hours prior to the procedure. You can take your usual medications with a small sip of water early on the morning of the procedure.

What happens during an EP Study?

During an EP Study, electrical catheters each about 2mm diameter are passed up from an incision in the groin, through the veins and into the chambers of the heart. They are positioned in the right atrium, near the AV node, in the ventricle and in the heart’s own draining vein (coronary sinus) which runs around the back of the heart to help us identify any of the extra connections (bypass tracts). With the catheters in place, your EP will both record electrical activity (shown on a video screen) and stimulate the heart at various locations.

We can then assess the conduction properties, presence of extra connections and try to bring on the patient’s tachycardia. In the case of curable arrhythmias (SVTs, VTs, atrial flutter and atrial fibrillation) a radiofrequency ablation (RFA) may be also performed.

Each individual EP Study can greatly vary in length. Your doctor will discuss this with you prior to your procedure. The procedure is performed in the Cardiac Catheter Laboratory. We use a sedative to make you drowsy and comfortable, but general anaesthesia is rarely required. Many patients, however, sleep through the whole EP Study procedure.

What happens after an EP Study?

The catheter insertion site, heart rhythm and basic vital signs such as blood pressure, pulse and breathing will be carefully monitored usually for several hours following the procedure. Before you are discharged from hospital, you will be advised on matters such as wound care, medication changes and level of activity. If you are discharged on the same day, you will need to arrange for someone to escort you home, and where possible, have someone stay with you overnight.

Your doctor will advise on any symptoms where you should seek immediate help. These may include symptoms such as chest pain, and bleeding, discharge or excessive pain from the insertion site.

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