What are the differences between stress testing with and without washout?
A stress test or stress electrocardiogram is a screening and prevention examination. It measures cardiac electrical activity using an ECG during ongoing physical exercise and detects any electrical abnormalities.
This examination is carried out during a standardized test on a treadmill or a specific bike. It can be combined with other examinations, such as scintigraphy or tests to evaluate the patient’s breathing (by measuring the gases released when exhaling, by taking blood samples).
A stress test without washout is when the patient is taking medication prior to the test, such as antiarrhythmic drugs or beta-blockers, which will modify the heart’s response during physical effort. This may be done to check the effect of a drug treatment, or simply because it is impossible for the patient to stop their medication. If certain medications can be stopped before the test, the examination is said to be a “partial washout” test.
Conversely, a stress test with washout is when the patient is not taking any medication. The test therefore makes it possible to evaluate the heart’s natural response to exercise.
Why have a stress test?
This examination may be prescribed to:
- determine the origin of chest pain or palpitations,
- monitor the proper functioning of the heart after a myocardial infarction (heart attack),
- monitor the progression of another heart condition (angina pectoris, ARVD, etc.),
- patients with risk factors for developing heart disease (diabetes, overweight, high blood pressure, smoking, high cholesterol, family history), starting from the age of 40 in men and 50 in women.
Stress testing without washout is used to check the effectiveness of a drug treatment, adjust the dosage if necessary or assess a patient’s tolerance for exercise while taking medication
Stress tests can also be performed on high-level athletes to evaluate VO2 max (the body’s ability to use oxygen), MAS (maximal aerobic speed), HR max (maximum heart rate) or even the maximum power that an athlete can generate.
How to prepare for it?
Here are some tips to follow on the day of the examination:
- Do not fast but avoid eating a meal right before the examination: eat normally at least 2 to 3 hours before the start of the test,
- If you are taking any medication, take it as usual, unless advised not to by a physician,
- Do not smoke,
- Wear comfortable clothing for walking and pedaling quickly. Wear a top that is easy to remove to make it easier to put the electrodes into place.
How does the exam take place?
Stress tests are carried out in a hospital or clinic under the supervision of a cardiologist. They generally take place in a well-ventilated, cool room, between 18 and 20°C.
A stress test is carried out without anesthesia and is painless, however symptoms of a heart condition, which may be painful, can be triggered during physical exercise.
Prior to the test
When the patient arrives, the cardiologist will carry out a quick examination to check the patient’s ability to exercise, they will give them information about the test procedures and will obtain the patient’s written consent.
An initial resting electrocardiogram is performed and a blood pressure measurement is taken.
Before starting the test, a nurse applies the self-adhesive electrodes for the electrocardiogram to the patient’s chest.
If the patient’s blood pressure is too high, it is possible that the test will not be carried out.
During the test
The stress test lasts between 10 and 30 minutes with:
- A warm-up phase during which the cardiologist asks the patient to walk or pedal slowly depending on the device (treadmill or specific bike),
- Several successive stages (every 2 to 3 minutes) during which the cardiologist increases the treadmill’s speed and incline or the bike’s resistance to raise the heart rate until the maximum number of heartbeats is reached (Theoretical Maximum Heart Rate) depending on the patient’s age and health.
During exercise stress tests, the electrical activity of the heart and the patient’s blood pressure are recorded regularly.
During this test, it is important to:
- Avoid talking,
- Report any abnormal symptoms (feeling of discomfort, chest pain, tightness, shortness of breath, significant fatigue, palpitations).
The cardiologist may interrupt the stress test if any of the following occur:
- Significant drop or rise in blood pressure,
- Abnormal electrical changes in the ECG or heart rhythm disorders
- Significant leg fatigue,
- Paleness, weakness, dizziness,
- Premature exhaustion or shortness of breath,
- The patient wants to stop the test.
Contraindications to stress testing
The risks of cardiac stress tests are heart attack and sudden cardiac death, which occur in approximately 1 out of 5,000 tests. To limit these risks, there are several absolute and relative contraindications (if the risk seems reasonable).
Absolute contraindications:
- Heart attack occurring within 48 hours,
- Acute aortic dissection,
- Very narrow aortic stenosis or stenosis that triggers symptoms,
- Heart rhythm disorders that trigger symptoms or blood circulation problems,
- Acute myocarditis,
- Acute pericarditis,
- Acute pulmonary embolism,
- Acute pulmonary infarction.
Relative contraindications:
- High-grade atrioventricular block,
- Bradycardia,
- Electrolyte imbalance,
- High blood pressure,
- Obstructive hypertrophic cardiomyopathy,
- Inability to exercise due to mental or physical disabilities,
- Moderate or severe cardiac valve stenosis,
- Left main coronary artery (LMCA) stenosis,
- Systemic disease,
- Tachycardia.
Reviewed and approved by Marine Arnaud, MD, Cardiologist at Bordeaux University Hospital (CHU)
