Table of ContentsView AllTable of ContentsPurposeRisks/ContraindicationsBefore the TestDuring the TestAfter the TestResults
Table of ContentsView All
View All
Table of Contents
Purpose
Risks/Contraindications
Before the Test
During the Test
After the Test
Results
A nuclear stress test is an imaging test that requires you to be injected with a small radioactive tracer that helps doctors determine how well yourheartis functioning. The tracer will lose its radioactivity through natural decay in about a day or two.
Also known simply as a stress test, a nuclear stress test can show how well your heart is pumping and how well blood is flowing through it while you exercise on a treadmill or stationary bike. Depending on the imaging technology used, the nuclear stress test may be referred to as cardiac positron emission tomography (PET), cardiac single photo emission computed tomography (SPECT), or myocardial perfusion imaging (MPI).
Verywell / Emily Roberts
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Purpose of a Nuclear Stress Test
A nuclear stress test helps your healthcare provider visualize what is happening in your heart when you exercise. A nuclear stress test is different than a regular stress test. A regular stress test uses an ECG to record your heart rate and rhythm, while a nuclear stress test captures images of your heart.
The nuclear stress test uses a radioactive tracer to make a picture. The tracer is a very small amount of radioactive material that is delivered into your body through an intravenous (IV) line.
The tracer that is commonly used today is calledtechnetium-99 (Tc-99). It provides clearer images than the tracers used in the past. It also exposes a patient to less radiation.
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What the Test Is Looking For
The nuclear stress test creates two images. The first shows how blood flows to your heart when you are resting. The second shows the blood flow during exercise.
The test can show:
The images can tell your provider different things about your heart health:
What Happens During a Cardiac Stress Test
Who Needs a Nuclear Stress Test
A nuclear stress test is an important tool for diagnosing or monitoring heart problems likecoronary artery disease (CAD)orcongestive heart failure (CHF).
Your provider may order a nuclear stress test if you have certain symptoms of CAD, such as:
The test can also find blockages and help your provider judge how bad they are.
If you already have been diagnosed with CAD, your provider might want you to have the test because the results can help them come up with a treatment plan for you.
If you are being treated for CAD, the test can help your provider understand how well your treatment is working. It will also help your provider decide what kinds of daily activities and exercise you should be doing.
The nuclear stress test does not involve inserting medical instruments into your body. This means it is non-invasive. The test is thought to be the most accurate and non-invasive way to diagnose coronary artery blockages.
CAD can also be diagnosed with an invasive test calledcardiac catheterization—a procedure where a tube called a catheter is inserted into a blood vessel in the heart.
If you can have a nuclear stress test, you may not need to have cardiaccatheterization.
Risks and Contraindications
Radiation Exposure
During a typical nuclear stress test, you are exposed to 11millisievertsof radiation. This is about three times the dose of radiation that you get just from going about your normal, day-to-day life for one year.
The risk of radiation exposure to other people after a nuclear stress test is low. However, some healthcare providers recommend no close contact with children or babies for one to two days after a nuclear stress test. Out of an abundance of caution, you may also want to avoid close contact with pets.
Test-Related Complications
Possible risks of having a nuclear stress test that you should be aware of include:
Life-threatening complications rarely happen during a nuclear stress test. They are estimated to occur only in one out of every 10,000 exercise tests.
What Is Ischemia?
Who Should Not Get the Test?
Some people should not do nuclear stress testing.
If you have the following conditions, your provider may not want you to have the test:
Pharmacologic Stress Testing
People with physical limitations that make exercise difficult or impossible can have pharmacologic stress testing instead of exercise stress testing.This is done with drugs that cause the same stress on the heart as exercise.
The types of drugs used may include:
Vasodilators are usually preferred for the pharmacologic stress test. These are medications that dilate or open the blood vessels. Your provider will choose the best drug for your case if exercise is not an option.
It is normal to have some anxiety about having a nuclear stress test. Knowing how to prepare and what to expect may help relieve your nerves.
Timing and Location
Most nuclear stress tests are performed in a hospitaloutpatientdepartment.
You will probably be asked to show up at least 30 minutes before the scheduled test. You can expect to be at the hospital for at least four hours.
What to Wear
Since you will be exercising, bring comfortable, loose-fitting clothing and shoes that fit well. Many people bring gym clothes and walking or running shoes.
Most testing facilities will provide a place for you to change your clothes.
Food and Drink
You will be asked to not have any food or drink four to six hours before your test. You will also be asked not to smoke for four to six hours before you arrive.
You will also need to avoidcaffeinefor at least 24 hours before the test.
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Medications
It’s important that you tell your provider about all the medications you take, even over-the-counter ones. Ask your provider which medications you should take on the day of testing, and which you should not take.
For instance, your provider may tell you not to takebeta-blockers, nitroglycerin, or heart medications for 24 hours before the test. You may also need to stop aspirin,blood thinners, and asthma medications 48 hours before the test.
If you have diabetes, you’ll be given instructions onhow to take your medications on the day of the test.
Avoid taking any over-the-counter (OTC) medications before the test unless your provider says that it’s OK to take them.
Make sure you tell your provider about all the medications and supplements you’re taking, even the ones you get over the counter.
Cost and Health Insurance
A nuclear stress test can be expensive, but the cost varies from facility to facility. If you have health insurance, the cost will also depend on your coverage.
Mostmedical insurancewill cover a nuclear stress test if a qualified cardiologist says that you need it. To be sure, check with your insurance company before you have the test.
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What to Bring
You will probably have a few hours of downtime during the test. You may want to bring a book or have a game to play on your phone to pass the time.
Other Considerations
If possible, bring a family member or a friend with you on the day of the test. This person can keep you company and offer support if you expect to get the results.
Pre-Test
This person will ask if your symptoms or medical condition have changed since you last saw your provider. You will also have a quick physical exam.
Your team will let you know what to expect during the test. You will also be given a chance to ask questions.
If you’re feeling nervous about the test itself, knowing what will happen during it can make it less overwhelming.
Most labs do one-day nuclear stress testing but it can also be done over two days. One-day testing is generally more convenient for patients.
If you are doing a one-day test, a resting image is captured first. The exercise part will be done later the same day. For a two-day test, the exercise part is usually done on the first day. The resting part is done on the second day.
During the resting test, an IV line will be put into one of your veins so the tracer can be injected. This image only needs a small dose of Tc-99. It is captured with a special camera that is used to scan the chest (gamma camera).
After about 20 minutes, you will lie down under the gamma camera. You will need to keep your arms above your head and lie still. It will take another 15 to 20 minutes to make the image. The image will show how the blood is flowing to your heart.
Before the exercise test, electrodes will be placed on your chest. The electrodes allow anelectrocardiogram(ECG) to be recorded while you are exercising. This test measures the electrical rhythm of your heart.
What Electrocardiograms Tell You About Your Heart
When the test starts, you will walk on a treadmill or pedal a stationary bike at a very slow pace. The level of exercise will increase every three minutes. The exercise will stop when one of these things happens:
Your ECG and vital signs will be monitored throughout the exercise and recovery periods. The exercise itself usually lasts for no more than six to 12 minutes.
When you have reached the maximum level of exercise, the tracer will be injected into your IV. At that point, you will stop exercising. For the exercise image, the Tc-99 dose is much larger than it was for the resting image.
Twenty to 30 minutes after you’ve finished exercising, you will lie under the gamma camera again. You will be asked to keep your arms above your head. The exercise cardiac image takes about 20 minutes to make.
How CAD Is Diagnosed
Most people can go back to their normal routine immediately after the test. This includes having meals, taking medications, and doing other activities.
How and when you get your results depends on the testing center. Most laboratories will give you an overview of the results right away. If the test finds problems, you’ll be given advice on what to do next.
If there are no obvious problems, you likely will not get the formal results of the test until a cardiologist looks at the images.
In this case, you’ll get your results from the provider who ordered the test. From there, you’ll discuss what, if anything, should be done next.
What Cardiologists Do
Managing Side Effects
Most people don’t experience any significant side effects from a nuclear stress test. When they do occur, side effects may include:
More serious side effects are uncommon. If you have any unusual symptoms after the test, call your provider.
Interpreting the Results of a Nuclear Stress Test
The interpretation of the results is different for everyone. You’ll need to discuss the results with your provider.
In general, the results of a nuclear stress test fall into three categories.
1. Both the resting and exercise cardiac images are normal
If both your resting and exercise images were normal, it means that:
Getting this result strongly suggests that there are no significant coronary artery blockages. In this case, the chance of having CAD is low.
Your healthcare provider will discuss the next steps with you. If your test is normal, you may not need more cardiac testing.
However, if your test was normal but there is strong evidence of CAD, your provider will likely recommend immediatemedical treatment. The goal will be to relieve symptoms and slow the progression of the disease.
You may also need to have a different test. For example, your provider may want you to have cardiac catheterization if:
Chest Pain With Normal Coronary Arteries
2. The resting cardiac image is abnormal
The resting cardiac scan may show an area where blood is not flowing normally to part of the heart.
If you get this result, it indicates that you’ve had a prior heart attack that caused permanent heart muscle damage.
3. The exercise cardiac scan is abnormal, but the resting image is normal
Getting this result suggests that there is a significant blockage in a coronary artery:
Different parts of the heart muscle may display any of these general findings.
For example, a person could have a “permanent” defect in one part of the heart muscle. This indicates a heart attack has occurred.
They may also have a “reversible” defect in another part of the heart muscle. This indicates there is a blockage but no permanent damage.
Summary
A nuclear stress test is used to find heart problems. The test uses a small amount of radioactive material to record blood flow to your heart. The test is done while you are at rest and exercising.
The nuclear stress test is generally very safe. There are some risks, like cardiac arrhythmias, chest pain, and, in rare cases, heart attack. The amount of radiation used is very small and does not increase your lifetime risk of cancer.
The results of the test can show if you have coronary artery disease, blockages, or a previous heart attack. Your provider will discuss the next steps with you, depending on the results.
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7 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Henzlova MJ, Duvall WL, Einstein AJ, Travin MI, Verberne HJ.ASNC imaging guidelines for SPECT nuclear cardiology procedures: stress, protocols, and tracers.J Nucl Cardiol.2016;23(3):606-39. doi:10.1007/s12350-015-0387-xAmerican Heart Association.Myocardial perfusion imaging (MPI) test.Harrison SD, Harrison MA, Duvall WL.Stress myocardial perfusion imaging in the emergency department–new techniques for speed and diagnostic accuracy.Curr Cardiol Rev. 2012;8(2):116–122. doi:10.2174/157340312801784916Wolk MJ, Bailey SR, Doherty JU, et al.ACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Card Fail. 2014;20(2):65-90. doi:10.1016/j.cardfail.2013.12.002National Library of Medicine.Nuclear stress test.Meher BR, Agrawal K, Gnanasegaran G.Review of adverse reactions associated with the use of common diagnostic radiopharmaceuticals.Indian J Nucl Med. 2021;36(2):163-167. doi:10.4103/ijnm.ijnm_219_20American Heart Association.Cardiac catheterization.
7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Henzlova MJ, Duvall WL, Einstein AJ, Travin MI, Verberne HJ.ASNC imaging guidelines for SPECT nuclear cardiology procedures: stress, protocols, and tracers.J Nucl Cardiol.2016;23(3):606-39. doi:10.1007/s12350-015-0387-xAmerican Heart Association.Myocardial perfusion imaging (MPI) test.Harrison SD, Harrison MA, Duvall WL.Stress myocardial perfusion imaging in the emergency department–new techniques for speed and diagnostic accuracy.Curr Cardiol Rev. 2012;8(2):116–122. doi:10.2174/157340312801784916Wolk MJ, Bailey SR, Doherty JU, et al.ACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Card Fail. 2014;20(2):65-90. doi:10.1016/j.cardfail.2013.12.002National Library of Medicine.Nuclear stress test.Meher BR, Agrawal K, Gnanasegaran G.Review of adverse reactions associated with the use of common diagnostic radiopharmaceuticals.Indian J Nucl Med. 2021;36(2):163-167. doi:10.4103/ijnm.ijnm_219_20American Heart Association.Cardiac catheterization.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Henzlova MJ, Duvall WL, Einstein AJ, Travin MI, Verberne HJ.ASNC imaging guidelines for SPECT nuclear cardiology procedures: stress, protocols, and tracers.J Nucl Cardiol.2016;23(3):606-39. doi:10.1007/s12350-015-0387-xAmerican Heart Association.Myocardial perfusion imaging (MPI) test.Harrison SD, Harrison MA, Duvall WL.Stress myocardial perfusion imaging in the emergency department–new techniques for speed and diagnostic accuracy.Curr Cardiol Rev. 2012;8(2):116–122. doi:10.2174/157340312801784916Wolk MJ, Bailey SR, Doherty JU, et al.ACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Card Fail. 2014;20(2):65-90. doi:10.1016/j.cardfail.2013.12.002National Library of Medicine.Nuclear stress test.Meher BR, Agrawal K, Gnanasegaran G.Review of adverse reactions associated with the use of common diagnostic radiopharmaceuticals.Indian J Nucl Med. 2021;36(2):163-167. doi:10.4103/ijnm.ijnm_219_20American Heart Association.Cardiac catheterization.
Henzlova MJ, Duvall WL, Einstein AJ, Travin MI, Verberne HJ.ASNC imaging guidelines for SPECT nuclear cardiology procedures: stress, protocols, and tracers.J Nucl Cardiol.2016;23(3):606-39. doi:10.1007/s12350-015-0387-x
American Heart Association.Myocardial perfusion imaging (MPI) test.
Harrison SD, Harrison MA, Duvall WL.Stress myocardial perfusion imaging in the emergency department–new techniques for speed and diagnostic accuracy.Curr Cardiol Rev. 2012;8(2):116–122. doi:10.2174/157340312801784916
Wolk MJ, Bailey SR, Doherty JU, et al.ACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Card Fail. 2014;20(2):65-90. doi:10.1016/j.cardfail.2013.12.002
National Library of Medicine.Nuclear stress test.
Meher BR, Agrawal K, Gnanasegaran G.Review of adverse reactions associated with the use of common diagnostic radiopharmaceuticals.Indian J Nucl Med. 2021;36(2):163-167. doi:10.4103/ijnm.ijnm_219_20
American Heart Association.Cardiac catheterization.
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