Echocardiogram vs Electrocardiogram

  • 1st Revision: Tamara Rapajic
  • 2nd Revision: Kaamya Mehta[Linkedin]
  • 3rd Revision: Jasmine Yeh[Linkedin]

Before considering these types of heart tests, it is important to understand the use of them. Below we will discuss: what each of these tests are, what they are used for, what they can detect, and why they are ordered.

What is an echocardiogram and when is it used?

An echocardiogram, sometimes referred to as sonar of the heart or cardiac echo, is essentially an ultrasound of the heart. Using a small probe that sends out high-frequency sound waves, echoes are created as the sound waves reflect off different organs and body parts. These echos can then be used to generate a moving image of the cardiac muscle (i.e. heart), allowing your doctor to see not only the structure of your heart, but also how your heart chambers and valves are functioning as it is pumping blood to the rest of your body.1,2

There are a number of different types of echocardiograms, such as transthoracic echocardiography, stress echocardiography, transesophageal echocardiography, fetal echocardiography, and three-dimensional echocardiography. The most common type of echocardiogram is the transthoracic echocardiography, which is the one discussed in this article.

Echocardiogram is an extremely safe and non-invasive test that can be used to help doctors diagnose heart disease and to determine the need for more tests. From this procedure, you can get guidance for the next steps in treatment or monitoring changes of an existing diagnosis.

What problems can an echocardiogram detect?

An echocardiogram can tell us a lot about your heart, such as the size and how efficient it is at pumping blood. It can detect a multitude of heart problems, including:

  • Blood clots in the heart arteries (e.g. aorta) and blood vessels
  • Build-up of fluid in the pericardium, a thin sac that surrounds the heart
  • Enlarged heart or thick and stiff ventricles
  • Heart defects from birth (a.k.a. congenital heart disease)
  • Issues with the heart valves (i.e. tricuspid and mitral valves)

Moreover, a type of echocardiogram, the Doppler echocardiogram, allows doctors to assess cardiovascular hemodynamics (i.e. how well blood flows between your heart chambers and through the valves).

Why would an echocardiogram be performed?

An echocardiogram is used by doctors to assess your heart health and is typically ordered if you have a family history of heart disease or if you display signs and symptoms of heart disease. Such signs include irregular heartbeat, chest pains, shortness of breath, and swelling of the legs.

What is an electrocardiogram (ECG) and when is it used?

An electrocardiogram, commonly abbreviated as EKG or ECG, is a simple, non-invasive test that records your heart’s electrical activity and rhythm. Typically, 10-12 electrode patches (that are connected to an ECG machine by wires) are stuck on your chest, arms, and legs. These electrode patches pick up electrical signals produced by the heart and record them, generating the commonly seen heartbeat wave.3

It is a quick and safe measure of your heart health that is used by doctors during routine check-ups at the GP and screening of heart disease.4 

What problems can an ECG detect?

Like echocardiograms, an ECG can provide a lot of information about your heart health. Most simply, it shows your heart rate and its rhythm, detecting if it is irregular or steady. It also measures the timing and strength of each electrical signal passing through the heart. It can detect:

  • Abnormal heart rhythm (e.g. arrhythmias)
  • If you have had a myocardial infarction (a.k.a. heart attack) in the past
  • How a particular heart disease treatment is performing (e.g. pacemakers)
  • Blockage or narrowing of arteries

Why would an ECG be ordered? 

An ECG is ordered by the doctors and is typically used alongside other tests to determine heart health. It also aids in the diagnosis of heart problems. It is typically ordered if you display symptoms of heart disease, such as chest pains, lightheadedness/dizziness, shortness of breath, rapid pulse or heart palpitations (i.e. pounding heart at rest), and fatigue that leads to an inability to exercise.

How do these two tests work together?

Echocardiograms and ECGs are some of the quickest and simplest non-invasive heart tests available. ECGs are the most ordered heart tests, whereby every individual who has done a health check-up has likely had an ECG since it is used in the screening for heart disease. Echocardiograms are also very common, just not as common as ECGs. The criteria for an echocardiogram are slightly more specific, whereby it is only ordered when you already have symptoms and signs of heart disease.

As you may be able to deduce, ECGs are normally ordered first and if abnormalities are shown, your doctor will then order an echocardiogram. ECGs provide simplistic but essential data on heart health (e.g. heart rate and rhythm); whereas echocardiograms allow doctors to obtain more in-depth knowledge of the function and structure of the heart chambers and valves.

Why do I need an echocardiogram after an ECG?

An echocardiogram will be ordered after an ECG if you present abnormal or unexpected ECG results, such as irregular heart rhythm or heart palpitations. Echocardiograms allow your doctor to observe more accurate information that cannot be gathered through ECGs. For example, it can aid your doctor in determining underlying structural abnormalities of the heart that could have led to the change in cardiac function which was observed in the ECG report.

Moreover, if an ECG indicates that there may be a blockage or narrowing of an artery in your heart or suggests that you have had a heart attack in the past, your doctor will likely order an echocardiogram to examine the extent of harm the heart attack had done to your heart structure and function.  

Is an echocardiogram more accurate than an ECG?

Yes. An ECG can only provide information about an individual’s heart rate and rhythm, which can be used as clues to indicate potential abnormalities, such as enlargement of heart chambers. On the other hand, echocardiograms produce moving images of the heart that can be used to show the heart’s structure and function. Thus, it can specifically pinpoint the areas of the heart that are damaged, and thus, are not functioning properly as a result. 

Hence, whilst ECGs can provide crucial information that can be used as clues for diagnosing heart disease, echocardiograms are more accurate as they can be used for diagnosis, as well as and pinpointing where the damage has occurred.

Heart Ultrasound vs. Echocardiogram vs. EKG vs. ECG

Though echocardiogram is the correct scientific term for the test, echograms are also commonly referred to as a ‘heart ultrasound’ or ‘cardiac echo’, and sometimes, just simply an ‘echo’. Similarly, though electrocardiogram is the scientific term for the test, it is typically abbreviated as EKG or ECG.

Thus, where heart ultrasound and echocardiogram are interchangeable terms for echocardiograms, EKG and ECG are interchangeable terms for electrocardiogram. They are just different names for the same test!


In summary, echocardiogram and ECGs are two of the most used heart tests and are commonly used in conjunction, as they are complementary to each other. ECGs are typically used to screen for heart disease, and show information about the heart rate and rhythm using electrode patches that detect electrical impulses that pass through the heart. Echocardiograms are ordered by doctors if abnormalities in the ECG report are observed. Echocardiograms can be used in the diagnosis of a heart disease, as they can pinpoint exact areas in the heart that are damaged in structure or not functioning properly. It uses high-frequency sound waves that produce echoes as they deflect off different organs and body parts to create moving images of the cardiac muscle. ECGs and echocardiograms are commonly used together or followed by one another (with ECG typically ordered first) as they are complementary tools that help doctors gather important information regarding an individual’s heart health.


  1. Omerovic S, Jain A. Echocardiogram [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2021. Available from:
  2. Echocardiography | National Heart, Lung, and Blood Institute (NHLBI) [Internet]. 2019. Available from:
  3. Electrocardiogram | National Heart, Lung, and Blood Institute (NHLBI) [Internet]. 2012. Available from:
  4. Sattar Y, Chhabra L. Electrocardiogram [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from:
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Jasmine Yeh

Master of Research - MRes, Clinical Research (Human Nutrition Pathway), Imperial College London
Hi! My name is Jasmine and I am currently doing an MRes in clinical research, specializing in human nutrition. I am extremely passionate about dissecting complex scientific papers and communicating them to those with non-scientific backgrounds to help them lead a healthy and balanced lifestyle. A healthy lifestyle to me should be maintainable, taking into account both physical and mental wellbeing, and is focused on prevention rather than treatment of diseases. I hope reading this article will help you take a positive step towards your idea of a healthy lifestyle!

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