What is a stress test?
A stress test is a very commonly performed test to learn:
- How well your heart pumps blood.
- Whether your heart is receiving an adequate blood supply.
- How you perform on physical activity (riding a treadmill or stationary bike) compared with other people your age and sex.
- If your symptoms (chest discomfort, shortness of breath, feeling like your heart is racing or even dizziness) can be reproduced while performing physical activity.
This makes it easier to identify and evaluate certain heart issues, such as:
- Issues with your muscle or valves.
- Adequate blood supply to your heart muscle.
- Electric stability of your heart at rest and during exercise.
Cardiac stress tests help healthcare providers determine whether you need additional — often more invasive — testing to confirm a diagnosis or if treatment might lower your heart attack risk and make you feel better.
How does a stress test work?
A heart stress test starts by making your heart pump harder and faster. For many people, this includes walking on a treadmill or riding a stationary bicycle. That’s why the test is often called an exercise stress test.
Healthcare providers assess your response to the increased workload by measuring:
- Blood pressure.
- Heart rate.
- Oxygen levels.
- Electrical activity in your heart.
- How hard your heart is working compared with others your age and sex.
Why might I need a stress test?
You may need this test to detect heart problems like:
- Congenital heart disease.
- Congestive heart failure.
- Coronary artery disease.
- Heart valve disease.
- Hypertrophic cardiomyopathy.
People with high-risk occupations (like pilots or professional athletes) may also need stress tests.
Who should have a cardiac stress test?
This test may be right for you if you have symptoms of heart disease, like:
- Angina, which is chest pain or discomfort due to poor blood flow to the heart.
- Arrhythmia, which is a rapid or irregular heartbeat.
- Shortness of breath (dyspnea).
- Feeling lightheaded or dizzy.
Stress tests are also for people with a heart disease diagnosis who:
- Would like to start exercising.
- Are undergoing treatment and healthcare providers need to determine how well it’s working.
- Face a higher risk of complications due to a personal or family history of heart disease.
- Have diabetes or other underlying conditions that increase your risk of heart disease.
- Require non-cardiac surgery and healthcare providers need to assess your risk of complications.
Providers may also do stress tests in people without known heart disease or symptoms to assess their risk for heart disease and heart attacks, especially if they have other risk factors like diabetes, high blood pressure, high cholesterol or a family history of premature heart disease.
Who should not have an exercise stress test?
Cardiac stress testing isn’t for everyone. You might not need the test if you have:
- A coronary artery disease diagnosis, have undergone treatment and not had new symptoms for years and are doing well on medical therapy.
- No history of risk factors for coronary artery disease or coronary disease or symptoms.
- A low risk of heart disease, including people who do not smoke, are physically active and eat a heart-healthy diet.
The test is also not for people with heart conditions that make stress testing unsafe (contraindications). These include:
- Aortic dissection.
- Endocarditis, pericarditis or myocarditis (heart muscle inflammation).
- Recent heart attack.
- Severe aortic stenosis (aortic valve narrowing).
- Uncontrolled abnormal heart rhythm (arrhythmia).
- Ongoing chest pain.
Why is exercise stress test eligibility important?
Your healthcare provider may decide not to have you undergo stress tests or repeat “routine” stress tests to help you avoid unnecessary costs and treatments. An unindicated stress test may show results that prompt healthcare providers to recommend additional testing you don’t need. Some of these tests, including a coronary angiogram, carry a higher risk of complications than stress tests.
Cardiologists consider your overall health in determining whether a heart stress test is right for you. This determination includes your:
- Family history of heart disease.
- Health history.
- Level of physical activity.
- Risk factors like smoking, diabetes, high blood pressure and high cholesterol.
What’s important to know about exercise stress testing in women?
People designated female at birth (DFAB) tend to experience heart disease differently than designated male at birth (DMAB). This makes it challenging to detect early-stage heart disease. In general, healthcare providers tailor their stress testing and method of imaging during stress testing based on your sex and age to obtain optimal results and minimize radiation and unclear test results.
Is cardiac stress testing safe?
If there are no contraindications, exercise stress tests are safe. Very few people experience complications. Trained healthcare providers, typically an exercise physiologist and a cardiologist, are present during your test in the rare event that you have a complication. They assess your performance, data and symptoms throughout the tests and immediately provide emergency treatment if it’s needed. You also have the option of stopping the stress test at any time if you become anxious or uncomfortable.
What are the different types of stress tests?
There are many methods for assessing heart function while it’s hard at work. All cardiac stress tests involve checking your heart rate, blood pressure, oxygen levels and electrical activity. But there are some differences.
Stress test types include:
Exercise stress test
This is the most common and basic heart stress test. It involves walking on a treadmill or riding a stationary bicycle. A well-trained exercise physiologist usually tailors the speed and elevation of the treadmill to your ability to walk and your overall fitness.
If you can’t exercise, you receive medications that make your heart pump harder and faster or dilate the artery supplying blood to your heart (coronary arteries). An electrocardiogram (ECG) captures your heart’s electrical activity. Exercise stress tests check for signs of coronary artery disease.
Exercise stress echocardiogram
An exercise stress echocardiogram is similar to the basic stress test but provides more detail. Healthcare providers perform an echocardiogram (ultrasound of your heart) before and at peak exercise. This cardiac imaging test uses sound waves to evaluate blood flow through your heart as well as the pumping chambers of your heart (muscle) and valve functions.
You might need a stress echocardiogram if the results of your initial stress test are unclear. This study enables healthcare providers to observe blood flow through the heart’s chambers as well as the effects of exercise.
Nuclear stress test
This advanced heart stress test uses safe levels of a radioactive substance and a cardiac imaging scan to assess heart function. A healthcare provider takes pictures of your heart before (at rest) and after you exercise. A cardiologist compares the amount of blood flow to the muscle of your heart at rest and after stress. A decrease in blood flow signal usually indicates a blockage in one or multiple arteries in your heart.
Nuclear cardiac stress tests can:
- Determine the severity of blockage of coronary artery disease.
- Assess whether previous treatments, such as stents or bypass surgery are working as they should.
- Help you avoid more invasive heart tests, such as cardiac catheterization.
- Show whether your heart is healthy enough for non-cardiac surgery or exercise.
Cardiac rehabilitation stress test
If your healthcare provider recommends cardiac rehabilitation, the program may include stress testing. Rehabilitation is a medically supervised exercise program that helps people with heart disease become more physically active.
Cardiac rehabilitation stress testing includes:
- Entrance stress test: Helps the rehabilitation team develop an exercise program that’s appropriate for your capabilities.
- Exit stress test: Enables the team to measure your progress and create a long-term exercise program after you complete rehabilitation.
How long is a stress test?
If you’re undergoing a basic stress test, the exercise portion lasts about 10 to 15 minutes. Additional time is necessary for getting ready to exercise and recovering afterward.
Stress tests that include echocardiography, nuclear imaging or MRI often are longer and may require you to be in the stress lab for up to three hours.
How do I prepare for an exercise stress test?
To prepare, you should:
- Not eat anything in the hours leading up to the test. If you’re having a nuclear stress test, you might not be able to eat until after your test.
- Avoid caffeine for 24 hours before testing. This includes coffee, tea, energy drinks and certain over-the-counter medications.
- Not smoke or use tobacco products.
- Stop taking certain prescription medications the day of your test. These include beta-blockers and asthma inhalers. Talk to your healthcare provider before stopping any medications.
- Try to relax. It’s natural to be nervous about heart testing, but feeling anxious can affect your results.
- Wear lightweight, comfortable clothes and sturdy walking shoes.
Are there special preparations people with diabetes need to be aware of?
It’s important not to eat before your test. However, you shouldn’t skip meals, especially if you’re taking diabetes medications. Talk to your diabetes care provider if you need assistance coordinating your meals and medications for test day.
If you own a glucose monitor, bring it with you so you can check your blood sugar levels before and after the test.
What happens during an exercise stress test?
Here’s what to expect during an exercise stress test:
- A technician takes your vital signs, including your resting heart rate and blood pressure.
- They attach small, sticky disks (electrodes) to your chest and arms. The electrodes connect to the EKG machine.
- You walk on a treadmill or pedal a stationary bicycle at an easy pace.
- Over time, the pace becomes more intense but still manageable.
- Technicians and exercise physiologists periodically ask how you are feeling.
- The test ends after maintaining your target heart rate long enough to capture readings about heart function, usually about 10 to 15 minutes. Your target heart rate is higher than when at rest and based on your age and fitness level.
- Technicians may end the test early if you experience severe symptoms or ask to stop.
How is a heart stress test different if I cannot exercise?
You receive medications through a vein in your arm (intravenously). The medications simulate the effects of exercise on your heart by making it pump harder and faster. It can take up to an hour for you to start feeling the effects.
What happens during a stress echocardiogram?
You follow the same steps as an exercise stress test. In addition, you lie down on a table before and after exercising to undergo an echocardiogram. This imaging study uses sound waves (ultrasound) to capture images of your heart pumping. It enables healthcare providers to observe the effects of exercise in more detail.
The whole test takes about an hour, but you exercise for less than 15 minutes.
What can I expect with a nuclear stress test?
For a nuclear stress test, you receive an injection of a radioactive substance. There is enough substance to show small details of heart activity during a sophisticated imaging study (SPECT or PET scan). The level of radiation is low and isn’t associated with any known, immediate side effects.
After your initial scan, you complete the stress test on a treadmill or stationary bicycle. If you can’t exercise, you’ll receive medication to make your heart work harder. After exercising, you undergo an additional scan.
A PET stress test can usually be performed in around 30 minutes.
The test usually takes three to four hours, but you exercise for less than 15 minutes.
What happens after my heart stress test?
After completing or stopping the test, healthcare providers monitor your symptoms, heart rate, blood pressure and ECG until it returns to a normal range. This takes about 15 minutes. Once your heart rate has recovered, you are free to go home.
What do normal stress test results mean?
If the results are normal, your heart is pumping as it should and there is adequate blood flow. What this means for your health depends on why you underwent stress testing:
- Heart disease evaluation: Symptoms are not due to a heart issue. You may need other evaluations to pinpoint the cause. For example, some people with anxiety experience chest pain and a racing heart even though their heart is healthy.
- Exercise or surgical planning: Your heart is healthy enough to start an exercise program or for you to undergo surgery.
- Heart disease monitoring: The treatments you are receiving are right for your needs. Your heart is capable of keeping up with your body’s demands.
What happens if my exercise stress test results are abnormal?
Abnormal results may mean you have heart disease. For signs of mild heart disease, healthcare providers may recommend lifestyle changes (like smoking cessation or an exercise and weight loss program) and medications to treat your diabetes, blood pressure or cholesterol to lower the risk of it worsening.
If abnormalities occur during the early stages of the test or affect large segments of heart tissue, additional tests may be necessary. These include:
- Cardiac catheterization.
- CT coronary angiography.
- Nuclear stress test.
- Stress echocardiogram.
Abnormal results may also mean your heart is not strong enough for exercise or surgery. Additional therapies may be necessary to help you avoid a heart attack or heart failure.