EKG (Electrocardiogram, ECG)

Medically Reviewed By William C. Lloyd III, MD, FACS

What is an EKG (electrocardiogram)?

An EKG (electrocardiogram, or ECG) is a painless test that records the electrical activity of your heart. An EKG helps your doctor diagnose and monitor many heart problems. These commonly include a heart attack, cardiac arrhythmias (abnormal heartbeats), and coronary artery disease (narrowing of the coronary arteries). 

An EKG is a safe, routine procedure. It is only one method to monitor and diagnose heart conditions. Discuss all of your testing options with your doctor or healthcare provider to understand which options are right for you.  

Types of EKG 

The types of EKG include:

  • Standard (resting) EKG involves measuring your heart’s electrical activity as you relax in a reclining or semi-reclining position. This is the most common type of EKG.

  • Stress test (exercise EKG or treadmill test) involves performing an EKG while you exercise, usually on a treadmill. It shows how exercise affects your heart. It helps to diagnose and assess coronary artery disease and other types of heart disease. Sometimes medication is given instead to mimic exercise’s effect on the heart.

  • Holter monitor (24-hour EKG or ambulatory EKG) involves wearing an electronic EKG recorder for 24 hours. It records the electrical activity of your heart over 24 hours. It helps diagnose arrhythmias (irregular or abnormal heartbeats).

  • Cardiac event recorders record an EKG over a longer period of time, up to a year or longer. Portable cardiac event recorders record the heart’s electrical activity when you get symptoms. Implantable loop recorders are implanted under the skin in your chest. They record your heart’s electrical activity continuously.

Why is an EKG (electrocardiogram) performed? 

Your doctor may recommend an EKG to help evaluate your heart health. It is a routine part of checkups, especially for people over the age of 40. 

An EKG by itself cannot diagnose all types of heart conditions or predict future heart problems. It provides important information about your heart health in relation to your age, physical exam, medical history, and other tests. 

Doctors use EKGs to help diagnose, determine the severity of, or monitor treatment of the following conditions:

  • Cardiac arrhythmias including heartbeats that are too fast, too slow, or irregular. Doctors also use EKGs to check how a pacemaker is functioning.

  • Cardiomyopathy, thickened or enlarged heart muscle

  • Congenital heart defects, birth defects of the heart

  • Coronary artery disease (CAD), a buildup of plaque on the walls of the coronary arteries. These arteries supply blood to the heart.

  • Heart attack, death of a portion of the heart muscle. A heart attack is usually due to coronary artery disease and a blood clot that blocks blood flow to the heart.

  • Heart failure, a weakened heart that cannot pump enough blood to the body

  • Heart murmurs, unusual or abnormal heart sounds heard with a stethoscope

  • Heart valve disease including narrowed valves and leaky valves

  • Pericarditis, inflammation of the sac that surrounds the heart

Your doctor may also perform an EKG to check your heart’s health before surgery. An EKG can also help your doctor determine if some symptoms are related to a heart problem. Symptoms include chest pain, dizziness, shortness of breath, fatigue, weakness, palpitations, passing out, or feeling a pounding, racing or irregular heartbeat.

Who performs an EKG (electrocardiogram)?

A doctor, nurse or technician performs an EKG. Your doctor may look at the test right away, but a cardiologist will provide the final results to your doctor. Doctors who order EKGs include:

  • Cardiac surgeons specialize in the surgical treatment of conditions of the heart and its blood vessels. Cardiac surgeons may also be known as cardiothoracic surgeons. 
  • Cardiologists and pediatric cardiologists are internists or pediatricians who specialize in diagnosing and treating diseases or conditions of the heart and its blood vessels.
  • Emergency medicine doctors specialize in the diagnosis and treatment of sudden illness or injury and complications of chronic diseases.
  • Interventional cardiologists are cardiologists who specialize in diagnosing and treating conditions and diseases of the heart and its blood vessels. They use nonsurgical, catheter-based procedures and imaging techniques.
  • Primary care providers including internists, family practitioners (family medicine doctors), pediatricians, geriatricians, physician assistants (PAs), and nurse practitioners (NPs). Primary care providers offer comprehensive healthcare services and treat a wide range of illnesses and conditions. 
  • Thoracic surgeons specialize in the surgical treatment of diseases of the chest, including the blood vessels, heart, lungs and esophagus. Thoracic surgeons may also be known as cardiothoracic surgeons.

How is an EKG (electrocardiogram) performed?

Your EKG will be performed in a hospital, clinic, doctor’s office, or sometimes in the home or an ambulance. A standard or resting EKG, the most common type of EKG, takes a few minutes. It generally includes these steps:

  1. You will recline in a comfortable position.

  2. Your provider will attach sticky patches, or electrodes, to your chest and possibly your arms and legs or hips and shoulders. This is painless. The electrodes are attached to an EKG machine by wires. Your provider will shave small areas of the chest as needed to apply the electrodes.

  3. You will remain still while the EKG machine records your heart’s electrical activity. The EKG results, called a tracing, will print out on paper. EKG tracings are often recorded and stored digitally as well.

  4. Your doctor will evaluate the EKG tracing and discuss the results with you.

Other types of EKGs also involve applying electrodes and the following procedures:

  • A cardiac event recorder involves taking an EKG tracing over a long period, up to a year or longer, using a portable or implantable device.

  • A cardiac stress test (exercise EKG or treadmill test) involves taking an EKG tracing while you exercise on a treadmill. Sometimes your doctor will also take pictures of your heart during the test using sound waves (stress echocardiogram) or a radioactive dye (nuclear stress test).

  • A Holter monitor (24-hour EKG or ambulatory EKG) involves taking your EKG tracing while wearing an electronic EKG recorder for 24 hours.

What are the risks and potential complications of EKG (electrocardiogram)?  

Most types of EKGs are safe, routine procedures without risks or complications. These EKGs include a standard EKG, 24-hour EKG, and cardiac event recorder. 

A cardiac stress test (exercise EKG or treadmill test) carries a small risk of complications including:

Your care team will watch you closely during a cardiac stress test. The team will stop the test if you have any problems. Be assured that your team is trained and equipped to treat complications.
Reducing your risk of complications

You can reduce the risk of certain complications of a cardiac stress test by: 

  • Ensuring that your care team is aware of your complete medical history including a history of allergies and heart problems

  • Notifying your care team right away of any concerns, such as chest pain, palpitations, dizziness, or shortness of breath

  • Telling all members of your care team if you have any allergies

How do I prepare for my EKG (electrocardiogram)?

You are an important member of your own healthcare team. The steps you take before an EKG can improve your comfort and outcome.

Your doctor may advise you not to smoke or drink caffeinated beverages for several hours before your EKG. For a cardiac stress test, your doctor may instruct you not to eat for four hours before your test. You may also need to stop taking certain medications, such as beta blockers, before your test. 

Questions to ask your doctor

It is common for patients to forget some of their questions about an EKG during a doctor’s office visit. . You may also think of other questions after your appointment. Contact your doctor with concerns and questions before an echocardiogram and between appointments. 

It is also a good idea to bring a list of questions to your appointments. Questions can include: 

  • Why do I need an EKG?

  • What type of EKG will I have?

  • How often will I need an EKG?

  • How should I take my medications before and after my EKG?

  • When and how can I expect to get my results?

  • What other tests do I need?

  • When should I follow up with you?

  • How should I contact you? Ask for numbers to call during and after regular hours.

What can I expect after my EKG (electrocardiogram)?

Knowing what to expect after your EKG can help you get back to your everyday life as soon as possible. 

How will I feel after my EKG?

You should not feel any ill effects or have any symptoms after your EKG. Tell your doctor right away about any symptoms, such as dizziness, chest pain, or shortness of breath. 

When can I go home?

Most people go home immediately after an outpatient EKG. Sometimes, patients stay to discuss the results with the doctor or cardiologist and to get more tests. If you are hospitalized, you will likely stay in the hospital for further evaluation and treatment.

When should I call my doctor?

It is important to keep your follow-up appointments after your EKG. Contact your doctor for questions and concerns between appointments. Call your doctor right away if you have any new or unusual symptoms, or symptoms that are not responding to your medications. Seek emergency medical care if you have chest pain or shortness of breath.

Was this helpful?
  1. Electrocardiogram (ECG). Bupa. http://www.bupa.co.uk/individuals/health-information/directory/e/electrocardiogram.
  2. EKG or Electrocardiogram. HeartSite.com. http://www.heartsite.com/html/ekg.html.
  3. ECG library. ecglibrarycom. http://www.ecglibrary.com/ecghome.html.
  4. Types of Stress Testing. National Heart Lung and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/stress/types.html.
  5. What Is an Electrocardiogram? National Heart Lung and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/ekg/
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 15
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