What is a nuclear stress test?

If you have a heart problem, the right treatment plan can help manage symptoms and reduce your risk of experiencing complications, such as a heart attack. When designing and monitoring your treatment plan, your healthcare provider may order a nuclear stress test to gain insight into how your heart is functioning. This test provides an assessment of any significant blockages of heart arteries, called coronary arteries, which supply blood to heart muscles.

A nuclear stress test involves taking images of the heart while you’re at rest and after exercise. The purpose of the test is to see how blood flows into and around your heart. To make the images as detailed as possible, patients receive an injection of a small amount of a radioactive substance before each set of pictures. This is called a nuclear scan, which allows your healthcare provider to see how an organ is functioning.

In most cases, healthcare providers order a nuclear stress test to aid in the diagnosis and treatment of coronary artery disease. This disease occurs when arteries are damaged or diseased, limiting blood flow to the heart. Images produced during a nuclear stress test can allow your healthcare provider to see how much blood is reaching your heart and locate any blockages. This can help with developing the right treatment plan for your needs.

Your healthcare provider may also order a nuclear stress test for other reasons, such as:

• Assessing the amount of damage to your heart caused by a heart attack
  
• Diagnosing the cause of angina (chest pain)
• Evaluating how well a medication or treatment is working
• Determining whether it is safe for you to undergo a surgical procedure or start an exercise regimen

Prior to the test, your healthcare provider will give you instructions on how to prepare. Some potential instructions include:

• Avoiding caffeine and certain medications for 24 hours before the test
  
• Fasting for a few hours immediately before the test
• Abstaining from smoking prior to the test
• Wearing athletic shoes and comfortable clothing
• Bringing along a rescue inhaler for asthma or a lung problem, if applicable
• Refraining from the use of body lotions, oils and creams on the day of the test

At the beginning of the test, you’ll typically lie on a table. You’ll be given an IV that contains the radioactive tracer, and then you’ll rest for 15 to 45 minutes. After that, your healthcare provider will take images of your heart.

In most cases, you’ll be asked to walk on a treadmill at different speeds and angles of incline, and then rest again after a second injection of tracer. After a 15- to 45-minute wait, a second set of images will be taken.

If you can’t exercise, your healthcare provider may instead prescribe medication that widens your blood vessels or increases your heart rate to simulate the effects of exercise.

Most people can return to their normal activities as soon as the nuclear stress test is over. During the test, you may experience symptoms such as:

• Chest pain
  
• Fatigue
• Shortness of breath
• Cramping in your legs and feet
• Flushing
• Nausea or vomiting
• Headache

Although nuclear stress tests are generally safe, there is a risk for complications, including:

• Abnormal heart rhythm
  
• Low blood pressure
• Heart attack, which is extremely rare

You’ll be monitored closely during the test so that your healthcare provider can respond quickly if any complications occur.

Normal results from a nuclear stress test indicate that you were able to tolerate exercise as well as other people of your age and sex. In most cases, it means that your arteries and heart muscle are normal. Abnormal test results usually occur due to reduced blood flow to the heart or scarring to the heart. Your healthcare provider will explain the test results and discuss the next steps with you.

Always discuss the results of your nuclear stress test with your healthcare provider, even if you have access to them online. While the results may look simple, reviewing them without a healthcare provider may lead to misinterpretation.

Updated August 2024.