Electrocardiogram (ECG)
A quick, usually not painful test that records the heart's electrical activity through small sticky pads on the skin, used to check the heart's rate and rhythm.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- An ECG is a quick, usually not painful recording of the heart's electrical activity, used to check heart rate and rhythm and to look for some heart problems.
- It captures the heart only at the moment it is taken, so a normal ECG does not rule out problems that come and go, and an abnormal trace does not always mean disease.
- It is usually usually not painful and carries essentially no risk; an exercise ECG, done while you walk or cycle, has a small added risk because it stresses the heart.
- Results are sometimes available the same day, but the meaning depends on your symptoms and other tests, so it is interpreted by a clinician.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Quick, usually not painful and widely available
As a stand-alone test to 'rule out' all heart disease, since a normal ECG cannot do this.
Electrodes are attached and your heart's activity is recorded. For a resting ECG you simply lie still for a few minutes; for an exercise ECG you walk or...
Clear information on who interprets the trace and when and how you get the result.
Electrodes are attached and your heart's activity is recorded. For a resting ECG you simply lie still for a few...
The electrodes are removed and you can usually go straight back to your normal activities. The skin may be...
A trace sometimes needs a doctor to interpret it. You may get the result the same day, or it may take days to...
Depending on the result and your symptoms, you may be reassured, started on treatment, or sent for further tests...
What is an electrocardiogram (ECG)?
An electrocardiogram (ECG, sometimes called an EKG or heart trace) is a test that records the electrical signals your heart makes as it beats. Small sticky pads called electrodes are placed on your chest, arms and legs and connected to a machine that prints or displays a trace of your heart's activity. It is usually quick and usually not painful.
An ECG can show your heart rate and rhythm and can help detect problems such as an abnormal rhythm (arrhythmia), the effects of a heart attack now or in the past, and some other heart conditions. It is often one of the first tests done when someone has symptoms like chest pain, palpitations or breathlessness, or before certain treatments.
An ECG records the heart at the moment it is taken. A normal ECG is reassuring but does not rule out every heart problem, especially symptoms that come and go, and an unusual-looking trace does not always mean something is wrong. Often it is one piece of the picture, used alongside your symptoms and other tests.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Resting ECG compared with an ambulatory (Holter) monitor
| Feature | Resting ECG | Ambulatory (Holter) monitor |
|---|---|---|
| How long it records | A few minutes | 24 hours to about a week |
| Best for | A snapshot of rate and rhythm | Symptoms that come and go |
| Where | Clinic, lying still | At home, during normal activities |
| Catches occasional problems | Only if happening at the time | More likely over a longer period |
| Comfort | Quick and usually not painful | Usually not painful but worn continuously, kept dry |
If your symptoms are intermittent, a normal resting ECG may not capture them, and a longer recording such as a Holter monitor may be suggested.
Preparing for your test
- There is usually little preparation for a resting ECG, but check any instructions your clinic gives you.
- Wear clothing that is easy to remove from the top half of your body, as electrodes go on the chest.
- Avoid heavy moisturiser, oil or talc on your chest beforehand, as electrodes stick better to clean, dry skin.
- Some chest (and occasionally limb) hair may need trimming so the electrodes attach properly.
- For an exercise ECG, wear comfortable clothes and shoes you can walk or cycle in, and ask whether to take or hold any medicines or eat beforehand.
- Tell the team about your symptoms, your medicines and any pacemaker or implanted device.
- Mention if you are pregnant or have any condition that limits exercise if you are having a stress test.
What happens
For a resting ECG, you lie down and a healthcare professional cleans the skin and attaches several small sticky electrodes to your chest, arms and legs. You stay still and relaxed for a short time while the machine records your heart's electrical signals. Recording usually takes only a few minutes, and the electrodes are then peeled off.
The test is usually not painful – the electrodes only record signals and do not give any electricity. You may feel a slight pull when the pads are removed, and the skin may be a little red afterwards.
An exercise ECG is done with electrodes in place while you walk on a treadmill or pedal an exercise bike, with the effort increased in stages. Your heart rhythm and blood pressure are watched throughout, and the test is stopped if you develop symptoms, become too tired, or the team has the information they need.
Is this test right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- As a stand-alone test to 'rule out' all heart disease, since a normal ECG cannot do this.
- For intermittent symptoms, where a single resting ECG is the wrong test and a longer recording is needed.
- An exercise ECG where exertion would be unsafe, or where the question is better answered by another test.
- As a substitute for emergency assessment when symptoms are severe or sudden.
Delay or rearrange if…
- You are acutely unwell and need emergency assessment rather than a routine test.
- For an exercise ECG, you have an unstable heart condition, active chest pain or an acute illness.
- You are unable to exercise for a stress test and an alternative has not been arranged.
- Necessary information, such as your medicines or previous ECGs, is not yet available.
Alternatives to discuss
- An ambulatory (Holter) monitor or longer recording for symptoms that come and go.
- An echocardiogram (heart ultrasound) to look at the heart's structure and function.
- Blood tests, a chest X-ray or other cardiac tests depending on the question.
- A medicine (pharmacological) stress test where exercise is not possible.
- Review by a clinician to decide whether any test is needed at all.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Benefits
- Quick, usually not painful and widely available
- Can show the heart's rate and rhythm and help detect an abnormal rhythm
- Can help show whether you are having, or have had, a heart attack
- Useful as a baseline and before certain treatments or medicines
- Helps guide whether further heart tests are needed
Risks & complications
- Mild skin redness or irritation where the electrodes were stuck
- A slight pulling feeling when the pads are removed
- Needing some chest hair trimmed for the electrodes to attach
- A normal trace that does not fully explain symptoms that come and go
- An unclear or borderline trace that needs repeating or comparing with an old recording
- Picking up a minor or unrelated finding that leads to more tests
- False reassurance if the test is normal but symptoms are intermittent
- During an exercise (stress) ECG only: chest pain, an abnormal rhythm, a marked blood-pressure change or, very rarely, a serious heart event – which is why it is monitored and can be stopped at once
A resting or ambulatory ECG carries essentially no physical risk – it only records signals and gives no electricity. The main limitation is that it captures the heart only at the time of recording, so a normal ECG does not rule out every problem. An exercise ECG adds a small risk because it deliberately stresses the heart, which is why it is supervised and monitored. Ask what your ECG can and cannot tell you, and what happens if it is normal but your symptoms continue.
Published figures to discuss
A resting or ambulatory ECG is essentially without risks – it only records electrical signals and gives no electricity – so meaningful complication rates do not apply, and the most useful figures are about accuracy and limitations rather than harm. The main issue is that a single recording captures only the moment it is taken, so it can miss problems that come and go, and an unusual-looking trace is not always abnormal. An exercise (stress) ECG carries a small risk because it deliberately stresses the heart, which is why it is supervised; specific risk depends on the person and the reason for the test.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Physical harm from a resting ECG | Essentially none | A resting ECG records electrical signals from the skin; it does not put electricity into the body. | Guide sourcesClinical context |
| Missing an intermittent rhythm problem | Recognised and common in practice | A normal ECG lasting seconds cannot rule out palpitations or blackouts that happen hours, days or weeks apart. | Guide sourcesClinical context |
| False-positive or incidental abnormality | Recognised | Normal variants, lead placement and non-specific changes can trigger further tests. Interpretation needs symptoms and clinical context. | Guide sourcesClinical context |
| Normal ECG during serious symptoms | Clinically important | Chest pain, severe breathlessness, collapse or stroke symptoms should be assessed urgently even if a previous ECG was normal. | Guide sourcesClinical context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no physical recovery from an ECG. What matters afterwards is who interprets the trace, what it means alongside your symptoms, and when you will get the result.
- No physical after-effects from a resting or ambulatory ECG
- Slight redness or itch where the electrodes were attached
- Feeling tired for a short while after an exercise ECG
- Waiting a little for the trace to be interpreted and reported
- Being asked for a repeat or a longer recording if the picture is unclear
Aftercare
- You can usually return to normal activities immediately after a resting or ambulatory ECG.
- If the skin is irritated where the pads were, a simple moisturiser usually helps.
- After an exercise ECG, follow any advice to rest briefly and to resume medicines as instructed.
- Make sure you know who will interpret the trace and when and how you will get the result.
- Ask what the result means alongside your symptoms and whether any further tests are needed.
- Seek urgent help if you develop severe chest pain, fainting or sudden breathlessness, rather than waiting for the result.
- Keep a note of your symptoms to discuss with the clinician reviewing the ECG.
- Easy-to-remove top-half clothing for the test
- Comfortable clothes and shoes for an exercise ECG
- List of your medicines, and any advice on holding them for a stress test
- A note of your symptoms and when they happen
- Knowing who interprets the trace and when results are due
- A way to ask questions about the result afterwards
- Awareness of which symptoms need urgent care
⚠ Get urgent help if…
- Severe or spreading chest pain, or chest pain with sweating, sickness or breathlessness – call 999
- Fainting or blacking out, or nearly doing so
- Sudden or severe breathlessness
- A very fast, very slow or irregular heartbeat while feeling unwell or faint
- During or just after an exercise ECG: chest pain, severe dizziness or feeling you might collapse – tell the team at once
- Sudden weakness, numbness or difficulty speaking (possible stroke) – call 999
- Any symptom your clinician told you to treat as urgent
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A good result means the team gets a clear recording that, together with your symptoms and any other tests, helps answer the question being asked – whether that is reassurance, a diagnosis, or a reason to do more tests.
An ECG shows the heart at the moment of recording. A normal ECG is reassuring but cannot rule out every heart problem, particularly symptoms that come and go, and an abnormal-looking trace is not always a sign of disease. That is why the trace is interpreted by a clinician in the context of your symptoms, and why a longer or repeat recording is sometimes needed.
An ECG is a snapshot, so its usefulness is mainly at the time it is taken and as a comparison for future recordings. If your symptoms change, or time passes, the test may need repeating, and intermittent problems may need a longer recording such as a Holter monitor to capture them.
Related tests, treatments or support
An ECG is often done alongside other heart tests, such as blood pressure measurement, blood tests, an echocardiogram (heart ultrasound), or a longer heart monitor. It is also commonly done as part of a cardiology consultation or before certain treatments. Your clinician will explain which combination is useful for your situation.
Follow-up & long-term care
How you get your ECG result depends on where it was done – sometimes the same day, sometimes after a doctor has reviewed it. The clinician should explain what it shows in the context of your symptoms and what happens next, whether that is reassurance, treatment, or further tests. Make sure you know who to contact if you do not hear back or your symptoms change.
Repeat, follow-on and what comes next
- An ECG often needs to be repeated, compared with an older trace, or followed by a longer recording.
- Borderline or unclear traces are common and may need a clinician's interpretation or further tests.
- A normal ECG with continuing symptoms usually leads to more investigation rather than a stop.
- Findings are interpreted alongside symptoms and other tests, not in isolation.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Clear information on who interprets the trace and when and how you get the result.
- Interpretation in the context of your symptoms, not the trace alone.
- A sensible plan for further testing if the ECG is normal but symptoms continue.
- Advice on which symptoms need urgent care rather than waiting for the result.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The type of ECG (a standard resting ECG versus an exercise or ambulatory test)
- Whether it is done as part of a consultation or as a stand-alone test
- Who reports the trace and how quickly the report is provided
- The facility or clinic where it is carried out
- Any further tests the result leads to, charged separately
- Whether care is self-funded or covered by private medical insurance
- The fee for the ECG and what type is included
- Whether interpretation and a written report are included
- Whether it is part of a consultation fee or charged separately
- How quickly the result and report will be available
- The cost of likely further tests if the ECG is abnormal or unclear
- What happens if the test needs repeating
- The cancellation policy
On the NHS? ECGs are widely available on the NHS when clinically indicated, including in GP surgeries and hospitals; private ECGs may be used for speed or as part of a consultation or health check.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Treating a normal ECG as proof the heart is healthy.
- Not explaining that a single resting ECG can miss intermittent problems.
- Not telling you who interprets the trace and when you will get the result.
- For exercise testing, not explaining the small added risk and that the test can be stopped.
- Not clarifying which costs are extra in private care, including reporting and follow-up tests.
Marketing red flags
- Offering an ECG as a way to 'rule out heart disease' or guarantee a healthy heart.
- Selling ECGs as part of a package without clinical interpretation in context.
- Implying an abnormal-looking trace always means serious disease.
- Not explaining the limits of a one-off recording for intermittent symptoms.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- What are you hoping this ECG will show or rule out?
- What happens if it is normal but my symptoms continue?
- If it is abnormal, what would the next step be?
- Would a longer recording, such as a Holter monitor, be more useful for my symptoms?
- Who will interpret the trace, and when and how will I get the result?
- Should any of my medicines be changed before an exercise ECG?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my test, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this test not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Does an ECG hurt or give an electric shock?
How long does an ECG take?
Does a normal ECG mean my heart is fine?
Is an exercise ECG safe?
When will I get my results?
Is an ECG available on the NHS?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS – Electrocardiogram (ECG) British Heart Foundation – Electrocardiogram (ECG) British Cardiovascular Society – information for patients NHS – Diagnosing a heart attack
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
Related guides: Ambulatory ECG (24-hour Holter monitor) · Cardiology consultation · Echocardiogram (heart ultrasound) · Event recorder or implantable loop recorder · Exercise tolerance test (treadmill test)