What is a stress myocardial perfusion scan?
Myocardial perfusion imaging (MPI) is a non-invasive imaging test that shows how well blood flows through your heart muscle. It can show areas of the heart muscle that aren’t getting enough blood flow (ischemia) and can show heart damage from old heart attacks. This is called a nuclear stress test. It can also show how well the heart muscle is pumping (ejection fraction).
There are two types of stress myocardial perfusion scans. Treadmill exercise stress for people who are able to walk. The second is a chemical stress test in people who are unable to walk or reach their individual target heart rate.
Reasons for the procedure
MPI is used in patients with chest discomfort to see if the discomfort comes from lack of blood flow to the heart muscle due to narrowed or blocked heart arteries (angina). Myocardial perfusion imaging doesn’t show the heart arteries themselves, but can tell your physician with good certainty how many heart arteries are blocked, if any. MPI can also show if you’ve previously had a heart attack.
For example, depending on your circumstances, if you have chest pain and an abnormal MPI study, the next step may be performing acoronary angiogram. However, if the MPI study is normal, your physician now can look into other causes of chest pain that aren’t heart-related.
An MPI test shows how well blood flows through your heart muscle. If the test shows a lack of blood flow during exercise or stress, but is normal at rest, it could mean that an artery that carries blood to your heart is narrowed or blocked. If the test shows a lack of blood flow to a portion of the heart muscle during exercise or stress and at rest, it could mean that your heart muscle has scarring, possibly from a previousheart attack.
Risks to the procedure
MPI tests are generally safe for most people. MPI studies expose you to a low dose of X-rays. Experts disagree if X-rays at such low doses can cause cancer, but the possibility exists that no dose of X-rays, however low, is completely safe. Don’t take the test if your risk for a heart attack is low, or if there is no other reason (chest discomfort) to think that you have heart problems. If you’re pregnant or think you might be pregnant, or if you’re a nursing mother, tell us before you have this test because it can harm your baby.
Before the procedure
During the procedure
Specially trained technicians usually perform the test in a hospital or clinic with special equipment.
The test takes between 3 and 4 hours. Some labs may do the resting part of the test first, or do the resting and exercise tests on different days.
After the procedure
You can usually go back to your normal activities right away.