Nuclear Stress Test (Myocardial Perfusion Scan)

A nuclear stress test, also known as myocardial perfusion imaging, is a noninvasive test that measures blood flow through the heart, which can also indicate how well the heart is pumping and areas of the heart muscle that are not receiving adequate blood flow.¹

The nuclear stress test begins with an injection of a radioactive tracer, a radioactive dye that is absorbed into the heart cells. Once the dye is absorbed, an imaging machine will take pictures of your heart at rest and after exerting yourself.²

Nuclear stress tests use a very low dose of X-rays, but your radiation exposure is quite low and the test is considered safe for most people. Pregnant or nursing mothers should talk to their doctor before having this test, to avoid risk to the baby.³

• A nuclear stress test can be used to help diagnose, monitor, or guide treatment of heart disease:
• Diagnose coronary artery disease (damage or disease of the blood vessels that carry blood, oxygen and nutrients to the heart)
• Determine proper treatment for existing heart disease
• Monitor treatment effectiveness
• Establish safe levels of exercise
• Determine the cause of symptoms (e.g., chest pain, shortness of breath) that more routine tests have failed to uncover ⁴

Before your appointment:

• Tell your doctor about all medicines you take, including over-the-counter drugs, herbs, vitamins, and supplements. Do not stop taking any medicine unless advised to do so by your doctor.
• Follow all medical advice regarding what you can eat or drink before your appointment. You may be asked to abstain from caffeine for 24 hours prior to your test.
• 4 - 6 hours before your test, you may be asked to avoid eating and drink only water.
• The day of your test, don’t use oil, lotions, or skin creams.⁵

Bring to your appointment:

• Loose-fitting clothing
• Comfortable shoes you can exercise in
• Your inhaler, if you use one. Let the clinician administering your test know about your inhaler.⁶

At the beginning of your appointment, your medical team will confirm your medical history, ask you questions about your exercise habits, and check your heart and lungs.

Before the test begins, a technician will inject the radioactive tracer through an intravenous (IV) line placed in your arm. It may feel chilly when first injected, and will take about 20 - 40 minutes to be absorbed. You’ll be asked to lie flat and still on a table while the clinician takes images of the heart at rest.

The next part of the test is an exercise stress test. Sensors called electrodes will be placed on your chest, legs, and arms, where they will monitor the electrical signals that cause your heartbeats. You’ll have a cuff on your arm to measure your blood pressure, and you may be asked to breathe into a tube. The clinician administering your test will monitor your heartbeats, heart rate and blood pressure while you perform an exercise, usually walking on a treadmill or riding an exercise bike.

When your heart rate peaks or reaches a set rate, you will receive another radioactive tracer. After 20 to 40 minutes to allow it to absorb, more images will be taken of your heart, to see how it functions after exertion.⁷

After the exercise part of your test, you may be asked to stand still for a brief period before lying down. The monitors will remain attached while your heart rate returns to normal. You may need to schedule a follow-up appointment with your doctor to discuss the results.

Unless your doctor tells you otherwise, you should be able to resume your normal routine after the test. Drink plenty of water to help your body will flush the tracer out of your system.⁸

^1,3 American Heart Association, “Myocardial Perfusion Imaging (MPI) Test.” https://www.heart.org/en/health-topics/heart-attack/diagnosing-a-heart-attack/myocardial-perfusion-imaging-mpi-test
^{2, 4-8} Mayo Clinic, “Nuclear stress test.” https://www.mayoclinic.org/tests-procedures/nuclear-stress-test/about/pac-20385231