An electrocardiogram, or ECG, is one of the simplest and most commonly used tests for assessing the heart. It is quick, painless and can provide valuable information about how your heart is beating.
But what exactly does an ECG tell your doctor — and what doesn’t it tell you?
At Glasgow Medical Rooms, an ECG may form part of a comprehensive health assessment, particularly when looking at cardiovascular health alongside your medical history, blood pressure, lifestyle and other risk factors.
What is an ECG?
An ECG records the electrical activity of your heart.
Every heartbeat is controlled by electrical signals that travel through the heart, telling the heart muscle when to contract. An ECG detects these signals through small sticky electrodes placed on the skin and records them as a series of lines and waves.
A standard resting ECG usually takes only a few minutes and is painless. You simply lie still while the recording is made.
Importantly, an ECG does not send electricity into your body. It simply records the electrical signals produced naturally by your heart.
What can an ECG check?
An ECG can provide information about several aspects of your heart’s electrical activity.
- Your heart rate
An ECG can show how quickly your heart is beating.
A heart rate that is unusually fast or slow may sometimes require further assessment, depending on the individual and the circumstances.
- Your heart rhythm
An ECG can show whether your heartbeat appears regular or irregular.
This can help identify some heart rhythm problems, including arrhythmias. Certain rhythm abnormalities may be intermittent, however, meaning that a standard ECG may not capture them if they aren’t happening during the recording.
- Electrical conduction through the heart
The electrical signal needs to travel through the heart in a coordinated way. An ECG can provide information about how that electrical impulse is travelling and can identify certain conduction abnormalities.
- Signs of previous or current heart problems
An ECG can sometimes provide evidence of a current or previous heart attack and can contribute to the assessment of coronary heart disease.
However, an ECG is only one part of a cardiac assessment. A normal ECG does not necessarily mean that every aspect of your heart is completely normal.
Why might you have an ECG during a health assessment?
An ECG may be recommended because of symptoms such as:
- Palpitations
- Chest discomfort
- Dizziness or fainting
- Breathlessness
- An irregular pulse
It may also be used as part of an overall health assessment where your doctor considers your medical history and cardiovascular risk.
For someone who feels completely well, an ECG may provide additional information when considered alongside other measurements and investigations.
What happens during an ECG?
A healthcare professional places small sticky electrodes onto your skin, usually on your chest and limbs. These electrodes are connected to an ECG machine.
You’ll normally be asked to lie still for a short period while the machine records your heart’s electrical activity.
The test itself is painless. You may experience a little discomfort when the electrodes are removed, similar to removing a plaster.
For the most accurate recording, it’s important to remain relaxed and still during the test.
What does an ECG not check?
This is an important question.
An ECG is not a complete health check of your heart.
It records electrical activity, but it doesn’t provide a detailed picture of the structure of your heart.
For example, an ECG isn’t the same as an echocardiogram, which uses ultrasound to create images of the heart and can assess things such as heart valves and how well the heart is pumping.
An ECG also doesn’t measure your cholesterol or blood pressure, and it cannot by itself provide a complete assessment of your risk of developing cardiovascular disease.
This is why your doctor may consider your ECG alongside:
- Blood pressure
- Cholesterol
- Blood glucose or HbA1c
- Weight and BMI
- Waist circumference
- Smoking status
- Physical activity
- Diet
- Family history
- Your symptoms and medical history
What if my ECG is abnormal?
An abnormal ECG does not automatically mean that you have serious heart disease.
ECG results need to be interpreted in context. Sometimes an abnormal finding is harmless, while in other situations it may indicate that further investigation is appropriate.
Depending on the findings and your individual circumstances, your doctor may recommend further tests or monitoring.
This could include another ECG, blood tests, ambulatory ECG monitoring, an echocardiogram or referral to a cardiologist.
What if my ECG is normal?
A normal ECG can be reassuring, but it doesn’t rule out every possible heart condition.
For example, some heart rhythm problems happen intermittently and may not occur while you’re having a standard ECG. Longer-term monitoring, such as a 24–48 hour ambulatory ECG, can sometimes be used when symptoms such as palpitations are occasional.
Similarly, cardiovascular risk isn’t determined by an ECG alone.
The most useful assessment looks at the whole picture.
ECGs as part of a comprehensive health assessment
At Glasgow Medical Rooms, we take a preventative approach to health.
Where appropriate, an ECG can be considered alongside your medical and family history, blood pressure, body composition, lifestyle factors and blood tests to give your doctor a broader understanding of your cardiovascular health.
This is particularly useful when looking beyond individual test results and considering your overall cardiovascular and metabolic risk.
The aim isn’t simply to identify disease. It’s to identify potential risks early, help you understand your health and give you the opportunity to make informed decisions about your wellbeing.
Should you have an ECG?
Whether an ECG is appropriate depends on your individual circumstances, medical history, symptoms and your clinician’s assessment.
If you’re experiencing chest pain, significant breathlessness, fainting or ongoing palpitations, you should seek appropriate medical advice rather than relying on a routine health assessment.
For people interested in taking a proactive approach to their health, an ECG can be one useful component of a wider cardiovascular assessment.
Find out more about comprehensive health assessments at Glasgow Medical Rooms.
This article is intended for general information and does not replace individual medical advice. An ECG has limitations and should always be interpreted alongside your symptoms, medical history and other clinical findings.
