From the Guidelines
A nuclear stress test, also known as Myocardial Perfusion Imaging (MPI), is a diagnostic procedure that evaluates blood flow to the heart during rest and during physical stress, typically used to diagnose coronary artery disease. The test involves injecting a small amount of radioactive tracer into the bloodstream, which is then detected by a special camera to create images of blood flow to the heart muscle 1. Patients will typically exercise on a treadmill or stationary bike to stress the heart, though those unable to exercise may receive medications like adenosine, regadenoson, or dobutamine to simulate exercise effects.
Key Points to Consider
- The entire procedure takes 3-4 hours, with actual imaging sessions lasting 15-30 minutes 1.
- Patients should avoid caffeine for 24 hours before the test, fast for 4-6 hours prior, wear comfortable clothes and shoes, and inform their doctor about medications and allergies.
- The radiation exposure is minimal and considered safe, with the benefits of accurate diagnosis outweighing potential risks.
- This test helps physicians determine if chest pain is due to coronary artery disease, evaluate the effectiveness of cardiac treatments, and assess heart function after a heart attack.
Clinical Guidelines
- According to the 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline, pharmacological stress imaging with nuclear MPI or echocardiography is recommended in patients with known stable ischemic heart disease (SIHD) who have new or worsening symptoms not consistent with unstable angina (UA) and who are incapable of at least moderate physical functioning or have disabling comorbidity 1.
- The guideline also recommends pharmacological stress with nuclear MPI or echocardiography for patients with an intermediate to high pretest probability of ischemic heart disease (IHD) who are incapable of at least moderate physical functioning or have disabling comorbidity 1.
Diagnostic Value
- Nuclear MPI can provide valuable diagnostic and prognostic information for making clinical management decisions regarding the need for cardiac catheterization, coronary revascularization, or medical treatment 1.
- The test can also be used to evaluate the effect of stress on regional and global ventricular function, which has important diagnostic and prognostic implications that can affect patient management decisions 1.
From the FDA Drug Label
Regadenoson injection is a pharmacologic stress agent indicated for radionuclide myocardial perfusion imaging (MPI) in patients unable to undergo adequate exercise stress.
A nuclear stress test, also known as Myocardial Perfusion Imaging (MPI), is a diagnostic test that uses a small amount of radioactive material to evaluate blood flow to the heart muscle.
- It is used to diagnose and assess coronary artery disease.
- The test involves injecting a radioactive tracer into the bloodstream, which is then detected by a special camera that takes pictures of the heart.
- The images show how well blood is flowing to the heart muscle, helping doctors identify areas of reduced blood flow, which may indicate blockages or damage. 2
From the Research
Definition of Nuclear Stress Test
A nuclear stress test, also known as Myocardial Perfusion Imaging (MPI), is a diagnostic test used to evaluate the blood flow to the heart muscle [(3,4)]. It is commonly used to diagnose and manage coronary artery disease, which affects millions of patients each year 5.
Purpose of Nuclear Stress Test
The purpose of a nuclear stress test is to identify areas of the heart where blood flow is reduced, indicating potential coronary artery disease [(3,4)]. It is often used as an initial assessment for patients with suspected coronary artery disease, serving as a gatekeeper for cardiac catheterization 5.
How Nuclear Stress Test Works
During a nuclear stress test, a small amount of radioactive tracer is injected into the bloodstream, which is then imaged using a special camera [(6,4)]. The test is typically performed under stress, either through exercise or medication, to increase blood flow to the heart muscle [(7,6)].
Clinical Utility of Nuclear Stress Test
The clinical utility of nuclear stress testing has been evaluated in several studies. For example, one study found that achieving ≥10 METs with a negative stress electrocardiogram resulted in 94% sensitivity and 97% negative predictive value in identifying high-risk CAD 7. Another study found that in low-to-intermediate risk patients with chest pain and evidence of non-critical coronary artery stenosis, a follow-up cardiac nuclear perfusion imaging is of limited value 4.
Limitations and Risks of Nuclear Stress Test
While nuclear stress testing is a valuable diagnostic tool, it is not without limitations and risks. For example, one study found that regadenoson, a medication used in nuclear stress testing, can cause takotsubo cardiomyopathy, a rare but potentially life-threatening condition 6. Additionally, nuclear stress testing involves exposure to radiation, which can increase the risk of cancer and other health problems 7.