A stress test is commonly used to assess how the heart performs when it is working harder than usual. Many patients are referred for a stress test because they have symptoms during activity, or because there is a need to understand how the heart responds to physical exertion. Although the name can sound concerning, the test is well established, carefully supervised, and provides useful information when used appropriately.
Stress tests are often referred to as an exercise ECG. It looks at the heart’s electrical activity, heart rate, blood pressure, and symptoms while the body is under controlled physical stress.
Why a stress test is performed
The heart may behave very differently during exercise compared with rest. Some problems only become apparent when the heart is required to work harder.
A stress test may be recommended to:
- investigate chest pain or discomfort that occurs during exertion
- assess breathlessness related to activity
- look for evidence of reduced blood flow to the heart muscle
- assess exercise tolerance and fitness
- help guide further investigation or treatment
It is often used when symptoms are exercise related and when a resting ECG does not provide enough information on its own.
What happens during a stress test
A stress test usually takes place in a hospital or clinic setting with trained staff present throughout. Small electrodes are placed on the chest to record the ECG, similar to a resting ECG test. A blood pressure cuff is also used to monitor blood pressure during the test. You will then be asked to walk on a treadmill or pedal a stationary exercise bike. The level of exercise increases gradually in stages. Each stage is designed to make the heart work slightly harder than the last. During the test, the ECG, heart rate, blood pressure, and any symptoms are closely monitored. You will be asked how you feel and whether you experience chest pain, breathlessness, dizziness, or fatigue. The test continues until a target heart rate is reached, symptoms develop, or it is felt that enough information has been gathered. You can stop the test at any time if you feel unable to continue.
Is a stress test safe?
Stress tests are generally very safe when carried out in appropriate patients. Before the test, your medical history and current symptoms are reviewed to ensure that it is suitable. The test is supervised throughout, and it is stopped promptly if there are concerning symptoms or ECG changes. Serious complications are rare.
How to prepare for a stress test
You are usually advised to wear comfortable clothing and shoes suitable for walking or light exercise.
You may be asked not to eat a heavy meal beforehand. Instructions about medications vary depending on the reason for the test, so it is important to follow the guidance you are given. If you are unsure, this can be clarified before the appointment.
What a stress test can show
A stress test can provide information about:
- how the heart rate and blood pressure respond to exercise
- whether symptoms occur during exertion
- ECG changes that suggest reduced blood flow to the heart muscle
- overall exercise capacity
These findings help determine whether further investigation is required.
What a stress test cannot show
A normal stress test does not rule out all heart disease. Some forms of coronary artery disease may not produce clear changes on an exercise ECG, particularly in early stages.
The test also does not directly show the structure of the heart or the coronary arteries. For this reason, further tests such as an echocardiogram or a CT coronary angiogram may be recommended depending on the clinical picture.
After the stress test
After the exercise portion is complete, you will continue to be monitored briefly while your heart rate and blood pressure return towards normal. Most people can go home shortly afterwards and resume normal activities. The results are interpreted in the context of your symptoms, risk factors, and other test findings. An abnormal result does not always mean there is a serious problem, and a normal result does not always exclude heart disease. Context is essential.
When further tests are needed
If the stress test suggests possible reduced blood flow to the heart, or if symptoms remain unexplained, further investigation may be advised. This might include imaging tests that provide more detailed information about heart structure or coronary arteries. Equally, if the test is reassuring and symptoms are mild, no further testing may be required.
When to seek advice
A stress test is often one step in a wider assessment rather than a definitive answer on its own. It is particularly helpful when symptoms are related to exertion and need clarification.
If you have been advised to have a stress test, or if you would like to discuss whether it is appropriate for your symptoms, you can get in touch with me to arrange a review and talk through the options in a clear and measured way. A stress test provides valuable insight into how the heart responds to activity. When used appropriately and interpreted carefully, it plays an important role in understanding symptoms and guiding further assessment without unnecessary alarm.