What is an exercise tolerance test/ETT?
An exercise tolerance test is also known as an exercise stress test or treadmill test. It is usually done when coronary artery disease is suspected. A resting ECG can not tell whether you have coronary disease as it is performed when you are rest. An exercise tolerance test challenges your heart to see how well the blood supply through the coronaries copes with the demands of exercise.
The test requires you to walk on a treadmill with an adjustable slope and speed. Your heart rate, ECG and blood pressure are monitored at rest and during the test, whilst the incline and speed are gradually increased. Once the test has reached its target the treadmill will slow and the incline will return to normal. You will be monitored until you are fully recovered and a further ECG will be taken of your heart. The exercise is tailored to ensure that your heart is tested adequately without putting you at risk. It is not an endurance test and it can be stopped at any point if you do not feel that you can go on.
Your clinic appointment will be for a minimum of 20 minutes with the test itself lasting approximately 10 minutes.
If you have chest pain: Healthy arteries can cope with the increased blood flow that is required when you exercise. If you have developed narrowing in the arteries the heart muscle will not get enough oxygen and you may experience chest pain. Lack of oxygen may also produce abnormal ECG wave patterns.
Following a heart attack: To establish the risk of further cardiac events and to establish if current medication therapies are sufficient.
Following certain procedures on the heart: After angioplasty or stenting an ETT may be performed to establish how well the treatment has worked.
Please wear flat non-slip shoes suitable for brisk walking.
It is advisable to avoid a heavy meal and coffee shortly before your appointment but otherwise eat and drink as normal. Avoid taking strenuous exercise for 4 hours prior to the test.
If you are taking a beta blocker you may be asked to stop it for two days prior to the test. Carry on taking all other medication as usual. Beta blockers (such as Atenolol) slow down the heart rate and it is therefore difficult to reach the target rate required during an exercise test whilst taking them. However, in some circumstances, it is necessary to remain on the beta blockers so only stop them if advised to do so. If you are unsure of whether this applies to you, do not hesitate to call the Chiltern Hills Heart Clinic and we will be able to tell you if you are on a beta blocker and whether or not you should stop it for the test. You should bring your GTN spray if you have been prescribed one
The test is graded according to what symptoms you experience, the duration of exercise, changes on the ECG, and by your blood pressure and heart rate response to exercise.
Exercise tests are not perfect. The test does not identify all cases of coronary artery disease and the results can indicate an abnormality when there is no coronary artery disease. The accuracy of the test can be somewhat improved by radioactive isotopes into your vein (thallium or technetium) or by use of an echocardiogram.
Your Consultant will have carefully selected you to have this test and would not recommend it if it was not safe to do so. Any risks are extremely remote and you will be supervised fully at all times either by the Consultant or a fully qualified member of staff. The exercise is tailored to ensure that your heart is tested adequately without putting you at risk. You will be monitored throughout the test.
It is not an endurance test and you can stop the test at any point if you do not feel that you can go on.
Ideally you will achieve a predicted heart rate calculated specifically to you. If you fall short of this, it may be that not enough information has been achieved from the test and further investigations may be necessary.
You need to let the Doctor supervising the test know if you experience symptoms such as chest pain, shortness of breath, palpitations or dizziness.
On the completion of the test you will be told the result. If you need further tests or treatment this will be explained fully to you.
If you have arthritis or have respiratory problems and are unable to do an ETT, there are alternative tests that can be used where drugs (such as dobutamine, adenosine or dipyridamole) are given into the vein to make your heart work harder while you are at rest.