What is a nuclear stress test?

A nuclear stress test combines imaging technology, small amounts of radioactive material, and an exercise stress test to diagnose and monitor heart problems. Your doctor may use a nuclear stress test to diagnose coronary artery disease and assess damage from a heart attack or other heart problems. A nuclear stress test can also show how well your heart pumps blood.

A nuclear stress test, sometimes called a thallium stress test, is an important test because some heart problems can only be seen when the heart is under stress from exercising. A nuclear stress test also provides important information about how the heart is functioning. Other imaging methods, such as X-rays and CTs, do not show how the heart responds to stress.    

A nuclear stress test is only one method to monitor and diagnose heart conditions. Discuss all of your testing options with your doctor to understand which options are right for you.  

Why is a nuclear stress test performed? 

Your doctor may recommend a nuclear stress test to see if any areas of your heart are not getting enough blood and oxygen when stressed by exercise. A nuclear stress test is not a routine screening test. It cannot diagnose all types of heart conditions or predict future heart problems by itself. It provides important information about your heart health in relation to your age, physical exam, medical history, and other tests. 

Doctors use nuclear stress tests to help diagnose or monitor the following conditions:

  • Coronary artery disease (CAD), a buildup of plaque on the walls of the coronary arteries that supply blood to the heart
  • Heart attack, death of a portion of the heart muscle usually due to coronary artery disease and a blood clot that blocks blood flow to the heart
  • Heart failure, an inability of a weakened heart to pump enough blood to the body. A nuclear scan is not recommended for people with advanced heart failure.

Your doctor may also perform a nuclear stress test to:

  • Assess heart damage from a previous heart attack, injury, infection, or other problem 
  • Determine if your heart can tolerate a major surgery 
  • Determine if your symptoms are related to CAD. Symptoms can include chest pain, dizziness, shortness of breath, fatigue, weakness, palpitations, passing out, or feeling a pounding, racing or irregular heartbeat
  • Further evaluate abnormal heart test results, such as changes on a standard resting EKG

Who performs a nuclear stress test?

The following specialists perform nuclear stress tests:

  • Cardiologists and pediatric cardiologists specialize in conditions and diseases of the heart and blood vessels. Pediatric cardiologists further specialize in treating infants, children and adolescents.
  • Clinical cardiac electrophysiologists specialize in diagnosing and treating abnormal heart rhythms (arrhythmias) using heart and blood vessel imaging and technical procedures.
  • Interventional cardiologists specialize in diagnosing and treating conditions and diseases of the heart and blood vessels using nonsurgical, catheter-based procedures and specialized imaging techniques.
  • Cardiac surgeons specialize in the surgical treatment of conditions of the heart and its blood vessels. Cardiac surgeons may also be known as cardiothoracic surgeons.
  • Advanced heart failure and transplant cardiologists care for people whose heart failure no longer responds to conventional therapies and symptom management.

How is a nuclear stress test performed?

Your nuclear stress test will be performed in a hospital or heart clinic. The stress test takes two to five hours and generally includes these steps:

  1. You will undress from the waist up and wear a patient gown for modesty.
  2. Your care team will attach sticky, painless patches, or electrodes, to your chest, arms and legs. The electrodes are attached to an EKG machine by wires. The EKG machine records your heart’s electrical activity during the test. If you have a hairy chest, your provider may shave small areas to apply the electrodes.
  3. Your care team will also apply a blood pressure cuff to your arm.
  4. Your care team will start an IV in your arm and inject a radioactive tracer, often thallium.
  5. You will rest for about 10 minutes. Then, your team will take pictures of your heart. You will need to lie still on a padded table with your arms raised overhead as a large camera rotates around you to take the pictures.
  6. You will then exercise by walking on a treadmill. You will begin to exercise harder as the treadmill gradually moves more quickly and the incline increases. If you aren't able to exercise due to a medical condition or illness, your doctor may use a drug to simulate the effect of exercise on the heart. This is called a pharmacological nuclear stress test.
  7. When you reach your target heart rate, your care team will inject a different radioactive tracer, often technetium sestamibi (Cardiolite). 
  8. Your team will take more pictures with the nuclear scanner 15 to 30 minutes later.
  9. Your care team will watch your EKG and vital signs closely throughout the nuclear stress test. The team will stop the test if abnormalities occur or if you have symptoms, such as chest pain, dizziness, or shortness of breath.
  10. You will rest briefly after the test while your care team watches your vital signs for abnormalities and checks the images to make sure they are clear.
  11. You will go home right after an outpatient nuclear stress test.