Medically Reviewed By: Dr Paul Lim – MBBS, M.Med (Int Med), MRCP (UK), FAMS (Cardiology)
Electrophysiology (EP) Study EPS — Mapping the Heart's Electrical System in Singapore
An electrophysiology study (EP study, or EPS) is a minimally invasive test of the heart's electrical system. Thin catheters are guided through a vein to the heart, allowing a cardiac electrophysiologist to record its electrical signals and pinpoint the exact source of an irregular heartbeat — often in the same session as catheter ablation.
Clinical Experience
Your EP Study Is Performed by Dr Paul Lim
Senior Consultant Cardiologist & Cardiac Electrophysiologist
Dr Paul Lim is a Senior Consultant Cardiologist who subspecialises in heart rhythm disorders — performing electrophysiology studies, catheter ablation, and pacemaker and defibrillator implantation. He completed advanced fellowship training at Barts Heart Centre, London under Singapore’s HMDP award.
- MBBS (Singapore)
- M.Med (Int Med)
- MRCP (UK)
- FAMS (Cardiology)
- Fellow, European Society of Cardiology (FESC)
- Fellow, American College of Cardiology (FACC)
- Fellow, Heart Rhythm Society (FHRS)
What Is an Electrophysiology Study?
Your heart beats because of a precisely timed electrical system that tells the heart muscle when to contract. When those signals become disordered, the result is an arrhythmia — a heartbeat that is too fast, too slow, or irregular. An electrophysiology study looks at that electrical system directly, from inside the heart.
During the study, several thin, flexible wires called catheters are passed through a vein (usually in the groin) up to the heart. These catheters record the heart's own electrical signals and can deliver tiny, painless electrical impulses to safely provoke the abnormal rhythm. Combined with a 3D electroanatomical map — a real-time, three-dimensional reconstruction of the heart chambers — this lets the electrophysiologist see exactly where the arrhythmia begins.
Because it pinpoints the precise origin of a rhythm problem, an EP study is the diagnostic step that guides definitive treatment. When a treatable focus is found, catheter ablation is frequently carried out straight away in the same session.
Why You Might Need an EP Study
An electrophysiology study may be recommended to:
- Find the source of an irregular heartbeat — locating exactly where an arrhythmia arises so it can be treated.
- Investigate unexplained symptoms such as palpitations, dizziness, light-headedness or fainting (syncope), when simpler tests have not given the answer.
- Confirm and map an arrhythmia before ablation — particularly supraventricular tachycardia (SVT), AV nodal re-entrant tachycardia (AVNRT), Wolff-Parkinson-White (WPW) syndrome, atrial flutter and some forms of ventricular tachycardia.
- Assess the risk of a dangerous rhythm or sudden cardiac arrest in selected patients.
- Evaluate the heart's conduction system when a slow heartbeat (bradycardia) or heart block is suspected.
- Check whether a treatment is working, such as an anti-arrhythmic medication.
An EP study is usually arranged after an ECG, Holter monitor or implantable loop recorder has suggested an arrhythmia but a precise diagnosis is still needed to guide treatment.
Conditions an EP Study Investigates
An EP study is most useful for fast or complex heart rhythms, where knowing the precise electrical origin changes treatment.
- Supraventricular tachycardia (SVT) — including AVNRT and AVRT, where a short circuit in the heart's wiring causes sudden fast heartbeats.
- Wolff-Parkinson-White (WPW) syndrome — an extra electrical pathway present from birth, which an EP study can locate for ablation.
- Atrial flutter — a fast, organised rhythm in the upper chambers that maps predictably during a study.
- Ventricular tachycardia (VT) — fast rhythms arising from the lower chambers, where an EP study helps assess risk and guide treatment.
- Bradycardia and heart block — assessing a slow or blocked conduction system when the cause is unclear.
For the broader picture of how these rhythms are diagnosed and treated, see our guide to irregular heartbeat (arrhythmia).
Electrophysiology Study and Catheter Ablation
An EP study and catheter ablation are closely linked, and are frequently performed together in a single procedure. The study comes first: it diagnoses the arrhythmia and maps its precise origin. If a treatable focus is confirmed, ablation follows immediately — controlled energy is applied to the small area of tissue causing the abnormal rhythm to neutralise it and restore a normal heartbeat.
Doing both in one sitting means the rhythm can be diagnosed and treated in the same visit, avoiding a second procedure. For this reason, most patients preparing for an EP study are counselled about ablation beforehand and give consent for both, and the standard is an overnight stay with discharge the next day. Where the study is diagnostic only, treatment options are discussed with you afterwards.
How to Prepare for an EP Study
- Tell your electrophysiologist about all medications, vitamins and supplements you take — especially blood thinners, which may need to be adjusted for a few days beforehand.
- Mention any bleeding disorders, allergies, or the possibility of pregnancy.
- You will usually be asked to fast for about six hours before the procedure.
- Some patients have preliminary tests — such as blood tests, an ECG or a 2D echocardiogram — to confirm they are ready for the study.
- Arrange for someone to take you home afterwards, as you will have had sedation.
What to Expect During an EP Study
Before the procedure
Small ECG electrodes are placed on your chest to monitor your heart throughout. The catheter insertion site — usually a vein in the groin — is cleaned and numbed with a local anaesthetic, and you are given sedation to help you relax.
During the procedure
The electrophysiologist inserts the catheters and guides them to the heart using X-ray imaging (fluoroscopy) and a 3D mapping system. Gentle electrical impulses are used to record the heart's signals and, if needed, to bring on the abnormal rhythm so it can be studied. You may briefly feel your heart beating faster or stronger, or feel light-headed — tell the team if you have any chest discomfort or breathlessness. If a treatable arrhythmia is confirmed, catheter ablation is usually performed in the same session.
After the procedure
The catheters are removed and firm pressure is applied to the insertion site to prevent bleeding. You rest with the leg kept still for a few hours while the team monitors your recovery. Most patients stay overnight and go home the next day.
Recovery and Aftercare
Recovery from an EP study is usually quick. Once at home:
- Take it easy for a few days and avoid strenuous activity or heavy lifting, following your electrophysiologist's advice on when to resume normal activity.
- Keep the insertion site clean and dry. A small bruise is normal.
- Most people return to desk-based work within a few days.
Contact the clinic promptly if you notice increasing pain, redness, swelling or bleeding at the insertion site, a fever, or any coolness, numbness or tingling in the leg. Seek urgent care for chest pain, fainting or breathlessness.
Risks of an Electrophysiology Study
An electrophysiology study is generally safe, and serious complications are uncommon — in the region of 1 percent or lower. The British Heart Foundation likewise notes that complications from an EP study are rare. As with any procedure that involves catheters, there are some risks:
- Bleeding, bruising or infection where the catheter is inserted.
- Blood clots forming on a catheter; medication may be given to reduce this risk.
- Rarely, damage to the heart or its electrical system, or to a blood vessel, which may require further treatment.
Your individual risk depends on your heart condition and general health. Dr Paul Lim will explain the benefits and risks for your situation before you decide to proceed.
Been advised you may need an electrophysiology study? Speak with Dr Paul Lim.
Cost of an Electrophysiology Study in Singapore
Singapore's Ministry of Health publishes a fee benchmark for an electrophysiology study, giving you a reference point before you book.
- A consultation is required first A specialist consultation determines whether an EP study is right for you. See our cardiology fees for consultation charges.
- If ablation is done in the same session Catheter ablation is billed under a separate MOH benchmark (TOSP SD839H), in addition to the study.
- MediSave & Integrated Shield Plans Covered under MOH-approved surgical limits and generally by MediSave and IP riders; our team can help with pre-authorisation before admission.
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Electrophysiology Study FAQ
What is an electrophysiology study (EPS)?
An electrophysiology study (EPS) is a minimally invasive test that examines the heart's electrical system from the inside. Thin catheters are guided through a vein to the heart to record its electrical signals and, if needed, to gently provoke the abnormal rhythm so its exact source can be located. It is used to diagnose the cause of an arrhythmia and to plan treatment such as catheter ablation.
Why would I need an EP study?
An EP study may be recommended to identify the source of an irregular heartbeat, to investigate unexplained palpitations, dizziness or fainting, to assess the risk of a dangerous rhythm or sudden cardiac arrest, and to map an arrhythmia precisely before catheter ablation. It is most often used for supraventricular tachycardia (SVT), Wolff-Parkinson-White syndrome, atrial flutter and some forms of ventricular tachycardia.
Is an electrophysiology study done at the same time as ablation?
Often, yes. When a treatable arrhythmia is confirmed and mapped during the study, catheter ablation is usually carried out in the same session — so the rhythm can be diagnosed and treated in one visit. In some cases the study is diagnostic only, and treatment is discussed afterwards.
How long does an electrophysiology study take?
A diagnostic electrophysiology study usually takes about 30 to 60 minutes. If catheter ablation is carried out in the same session, the overall procedure takes longer, depending on the type and complexity of the arrhythmia.
Is an EP study done under general anaesthetic?
Usually not. Most electrophysiology studies are performed under a local anaesthetic at the catheter insertion site together with sedation to keep you comfortable and relaxed. General anaesthesia is used in selected cases, which your electrophysiologist will discuss with you beforehand.
Is an electrophysiology study safe, and what are the risks?
An electrophysiology study is generally safe, and serious complications are uncommon — in the region of 1 percent or lower. Possible risks include bleeding, bruising or infection where the catheter is inserted, and blood clots. Rarely, there can be damage to the heart or its electrical system. Your electrophysiologist will discuss your individual risks before the procedure.
What is the difference between an EP study and an ECG?
An ECG (electrocardiogram) is a quick, painless recording taken from the surface of the skin, and it captures the heart's rhythm at that moment. An electrophysiology study is an invasive test in which catheters are placed inside the heart. It can record electrical activity directly, provoke an arrhythmia that comes and goes, and pinpoint its exact origin — information an ECG alone cannot always provide.
Do I need to stay overnight, and how long is recovery?
Because an EP study is usually performed in the same session as catheter ablation, most patients stay overnight and go home the next day. You rest with the leg kept still for a few hours after the catheters are removed. Light activity is fine the next day, and most people return to desk-based work within a few days, following your electrophysiologist's advice.
How much does an electrophysiology study cost in Singapore?
Singapore's Ministry of Health publishes a surgeon fee benchmark for an electrophysiology study without ablation (TOSP code SD739H) of S$3,379 to S$6,104, inclusive of GST (S$3,100 to S$5,600 before GST). This covers the cardiologist's professional fee only — hospital facility charges and anaesthesia are billed separately, and fees vary with complexity. If catheter ablation is carried out in the same session, it is billed under a separate benchmark. See the cost section above.
Who performs the electrophysiology study?
Your electrophysiology study is performed by Dr Paul Lim, a Senior Consultant Cardiologist and Cardiac Electrophysiologist who subspecialises in heart rhythm disorders, with advanced fellowship training in the UK and Singapore.