ECG Test: What It Is, How to Prepare and What to Expect
An electrocardiogram (ECG) is a quick, painless test that records the heart's rate and rhythm. This article explains the types, how to prepare and what to expect.
Scientist and Chief Medical OfficerDr. Ambed Mishra, PharmD, PhDEducational information only, not medical advice. Always ask a qualified doctor about your own health. In an emergency call 112 (India) or 911 (US). Read the full disclaimer.
On this page
An ECG is one of the most common heart tests. It is usually quick and painless, and it can give doctors useful information about your heart's rhythm. This article explains what the NHS says about what to expect.
What is an ECG?
An ECG, or electrocardiogram, records the electrical activity of the heart, including its rate and rhythm. The NHS describes it as usually quick and painless.
Why is it done?
The NHS says an ECG may be used when doctors want to check for:
- A suspected heart attack
- Coronary heart disease
- Heart rate or rhythm problems (arrhythmias)
- A known heart condition, or another condition that affects how well the heart works
It can also be used before and during certain medicines. The NHLBI describes an arrhythmia as a problem with the rate or rhythm of your heartbeat.
Types of ECG
The NHS describes three main types:
- Resting ECG: you lie still for a few minutes while sticky patches called electrodes on your arms, legs and chest record the heart's signals.
- Portable ECG: electrodes are taped to your chest and connected to a recorder worn on a waist belt. It is usually worn for 24 to 48 hours, and up to 7 days. You cannot bathe or shower while wearing it. MedlinePlus describes a similar test called a Holter monitor, which is covered in another article.
- Exercise ECG (stress test): done in hospital while you walk on a treadmill or cycle. Exercise gradually increases and stops when symptoms appear or you are too tired. It usually lasts 40 to 60 minutes. If you cannot exercise, you may be given medicine that raises your heart rate.
How to prepare
The NHS suggests:
- Wear a top that is easy to take off
- Avoid body lotions, oils and talcum powder on your skin
- For an exercise ECG, avoid a heavy meal and caffeine beforehand
- Your chest may need to be shaved and cleaned so the patches stick
- You can ask for a chaperone to be present
Ask your clinic whether you should take your usual medicines on the day, and do not stop any medicine unless you are told to.
What happens
For a resting ECG, you remove clothing from the waist up behind a screen, and electrodes are attached. The test itself is brief. Removing the patches afterwards may cause slight discomfort, and a mild rash may appear where they were placed, the NHS says. The NHS page does not describe medical risks of the test.
Results
The NHS says results may be available the same day, but can take a few weeks depending on the type of ECG. A follow-up appointment may be needed. If you have not heard anything after a few weeks, contact the doctor who referred you. You can ask a health professional to explain any results you do not understand.
An ECG is one piece of the puzzle. An ECG that looks normal at one moment does not rule out all heart problems, and your doctor may suggest other tests, such as an echocardiogram, depending on your symptoms.
When to see a doctor
See a doctor if you have palpitations, dizziness, breathlessness or chest discomfort, so that they can decide whether you need an ECG. Do not wait for a test if you have emergency symptoms.
Call emergency services at once for chest pain that is tight or squeezing, pain spreading to the arms, neck or jaw, severe breathing difficulty, or if someone collapses and is not responding normally. Do not drive yourself to hospital.
In an emergency, call your local emergency number (112 in India, 911 in the United States).
Common questions
Is an ECG painful?
The NHS describes it as usually quick and painless. Removing the sticky patches afterwards may cause slight discomfort.
How long does an ECG take?
A resting ECG takes a few minutes of lying still, according to the NHS. An exercise ECG usually lasts 40 to 60 minutes.
How should I prepare?
The NHS suggests wearing an easy-to-remove top and avoiding lotions, oils and talcum powder. Before an exercise ECG, avoid a heavy meal and caffeine.
When will I get my results?
The NHS says results may be available the same day, but can take a few weeks depending on the type of ECG.
Important: please read
- Educational information only. This article is general health education. It is not medical advice, diagnosis or treatment. Reading it does not create a doctor–patient relationship with MyDoctor or with anyone else.
- Ask a qualified doctor. Always talk to a qualified, registered doctor about your own health. In India, that means a doctor registered with the National Medical Commission (NMC) or a State Medical Council. In the United States, a licensed physician. Elsewhere, a doctor licensed where you live.
- Never ignore or delay professional advice because of something you read here. Do not start, stop or change any medicine or treatment without your doctor.
- Emergencies: call 112 in India, 911 in the United States, or your local emergency number. Do not wait for an online answer.
- No product is endorsed. MyDoctor does not recommend any brand, product or supplement in this article.
- About the sources. This article summarises, in our own words, information from the public health bodies named under Sources. Health knowledge changes, and this summary may not reflect the latest research or your personal situation.
- Liability. To the extent permitted by law, MyDoctor (MODERNUS HEALTH TECHNOLOGIES PRIVATE LIMITED) accepts no liability for any decision made on the basis of this content.
Sources
- NHS. Electrocardiogram (ECG) - NHS www.nhs.uk
- NIH MedlinePlus. Holter monitor (24 h) - MedlinePlus medlineplus.gov
- NHLBI (NIH). Arrhythmias - NHLBI www.nhlbi.nih.gov
Dr. Ambed Mishra, PharmD, PhD
- Clinical Research
- Psychiatry
- Community Medicine
- Clinical Pharmacy
- Electronic Health Records
- Patient Outcomes Research
MyDoctormydoctor.socialMyDoctor by MODERN US HEALTH, Austin, Texas. Ahmedabad, Gujarat. Bangalore, India.
Dr. Ambed Mishra is a clinical (patient care) scientist, author and former professor. He is Group CEO and Chief Medical Officer of MODERN US HEALTH (MODERN US GROUP), Austin, Texas, the group behind MyDoctor, and a senior consultant who teaches and trains MD/DO physicians, PharmD and PhD professionals, nurses and other healthcare professionals in patient care in the United States and India.
More about Dr. Ambed Mishra
- More than ten years of full-time leadership in United States healthcare, building patient care services that improve medication adherence and bring doctors, pharmacists and nurses together around each patient.
- Leads the MD and engineering teams behind MyDoctor: clinic and hospital management software, electronic health records and telehealth for hospitals and physician groups in the United States and India.
- Former Assistant Professor and Clinical Preceptor at Rajiv Gandhi University of Health Sciences, Bangalore, and senior researcher with hospitals, universities and patient care groups in India and the United States.
- More than 30 published research and review articles and case reports, and more than 15 international conference presentations in India, Australia, Canada, the United States, Spain and other countries.
- Chief Medical Officer and Global Program Head of a nonprofit mission that helps cover hospital and doctor visit bills for patients in need in India, Nepal, the United States and other countries.
The author's office answers questions about articles, research, speaking and collaboration. It cannot give personal medical advice.