Electrocardiogram (EKG)

An EKG test is an easy way to get information to diagnose a problem with your heart. It doesn’t take long and doesn’t cause pain, but an electrocardiogram test can tell your healthcare provider if you’ve had a heart attack, heart failure or heart damage. It can also tell them if your heart rhythm isn’t normal or how well your pacemaker is working.


Illustration of how an EKG monitors electrical activity of the heart.
EKG showing heartbeat frequency and duration.

What is an EKG?

An electrocardiogram (EKG/ECG) uses temporary electrodes on your chest and limbs to monitor, track and document your heart’s electrical activity (which controls your heartbeats) for diagnostic purposes. A computer translates the information into a wave pattern your healthcare provider can interpret. This is a quick, noninvasive test that doesn’t hurt. You can get an EKG while lying down and resting or while you’re exercising as part of a stress test.

Types of EKG devices

Because a typical EKG tracks your heart’s electrical activity for a very short time, it probably won’t pick up irregularities that only happen once in a while. It’s like when your internet is acting up but seems fine when someone comes to repair it. To capture these erratic issues, your provider can give you:

  • Holter monitor: You wear this device for 24 to 48 hours to get a continuous recording of your heart’s electrical activity for that time frame.
  • Event monitor: You wear this device for a week or more and may need to click a button to start recording when you feel symptoms.

How to read an EKG

Your own internal pacemaker, your sinoatrial node, starts your heartbeat with an electrical signal. An EKG reads that signal and tracks its impact on your heart as it contracts and relaxes with each heartbeat.

Your healthcare provider will look at how much electrical activity there is, how strong it is and how much time passes between the different waves or peaks that represent the electrical impulses.

  1. Your upper heart chambers (atria), where your heartbeats start, create the first wave, or "P wave."
  2. Your lower heart chambers (ventricles) create the next wave, called a QRS complex.
  3. The third wave, or "T wave," shows your heart at rest or recovering after beating.


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What is an ECG vs. EKG?

Both terms mean the same thing: an electrocardiogram. EKG comes from the German word, which uses “k” instead of “c” in both parts of the word. However, it’s different from an echocardiogram, which is an ultrasound that creates images of your beating heart.

When would an EKG be used?

Your healthcare provider uses an EKG to:

  • Assess your heart rhythm to see if it’s normal or if you have arrhythmia.
  • Diagnose poor blood flow to your heart muscle (ischemia) because of coronary artery disease.
  • Diagnose a heart attack.
  • Diagnose abnormalities of your heart, such as heart chamber enlargement and abnormal
    electrical conduction.
  • Diagnose heart damage or heart failure.
  • Make sure you’re fit for an upcoming surgery.

They can also check on how your heart is doing since you:

  • Got a pacemaker.
  • Started taking medication for heart disease.
  • Had a heart attack.

Symptoms you can diagnose with an EKG

Your provider may give you an EKG test because you have:


Who performs an EKG?

A healthcare provider who’s a heart expert (cardiologist) usually orders or performs an EKG. However, other providers can give you this test, especially if you’re in an ambulance or an emergency room instead of at a scheduled appointment. You can get an EKG in your provider’s office, at a hospital or at an outpatient facility.

Test Details

How does an EKG work?

Electrodes or sensors your provider puts on your chest, legs and arms send information through wires to a computer that uses the data to make a wave chart. This shows the electrical activity that’s happening in your heart.


How do I prepare for an EKG test?

Before an EKG, you can eat and drink like you normally would. However, you’ll want to keep the following in mind before you get dressed on the day of your EKG test:

  • Avoid oily or greasy skin creams and lotions the day of the test. They interfere with electrodes making good contact with your skin.
  • Avoid full-length hosiery, as electrodes need to be placed directly on your legs.
  • Wear a shirt that you can remove easily to place the leads on your chest.

What to expect on the date of the EKG test

A healthcare provider will attach 12 electrodes with adhesive pads to the skin on your chest, arms and legs. To allow a better connection, your provider may shave hair that’s in the way. It takes about 10 minutes to attach the electrodes and complete the test, but the actual recording takes only a few seconds.

What to expect during an electrocardiogram test

For a resting EKG, you‘ll lie flat and relax while the computer creates a picture, on graph paper, of the electrical impulses traveling through your heart. If you’re doing a stress test, you’ll be walking on a treadmill during the test.

The electrodes will stay on your skin until the EKG test is done. You won’t feel anything different when the electrodes are communicating with the computer.

What to expect after an electrocardiogram test

Your healthcare provider will remove all of the sticky electrode patches and you can return to your normal activities.

What are the risks of an EKG test?

An EKG is a low-risk test. It doesn’t use radiation or put electricity into your skin. You might have some skin irritation after your healthcare provider removes the sticky patches that were attached to the sensors.

Results and Follow-Up

What type of results do you get and what do the results mean?

Your EKG results may show that you have:

  • A heart rhythm that’s irregular, too fast or too slow.
  • A heart attack (past or present).
  • Heart walls that are getting thicker (cardiomyopathy) or stretched out (aneurysm).
  • A problem getting enough blood to your heart.
  • Heart failure.

When should I know the results of the test?

If your healthcare provider is able to review your EKG test results right away, they may speak to you soon afterward. This is especially true in an emergency situation when you may need immediate treatment. However, if your electrocardiogram test is more routine or part of a group of tests before noncardiac surgery, you may not hear from your provider for a few days.

Your provider will keep your EKG records on file to compare with future ones.

When should I call my doctor?

Contact your healthcare provider if:

  • It’s been several days since your electrocardiogram test and you haven’t heard from them.
  • Your symptoms are worse than they were before your EKG test.
  • You have questions about the next steps after your provider makes a diagnosis.

A note from Cleveland Clinic

An EKG is a very quick and pain-free test your healthcare provider can do to check your heart rhythm and evaluate your heart. The information from your EKG will help your provider decide what treatment would be best for you. Be sure to keep your follow-up appointments with your provider and keep taking the medicines they prescribed for you.

Medically Reviewed

Last reviewed on 05/13/2022.

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