From the Guidelines
A myocardial perfusion scan should be ordered for patients with suspected or known coronary artery disease who have intermediate risk, unclear stress test results, or when standard exercise stress testing is not feasible, as it provides valuable information on coronary artery disease extent and severity, guiding treatment decisions regarding medical therapy versus revascularization. This recommendation is based on the most recent and highest quality study available, which emphasizes the importance of stress SPECT MPI in evaluating patients with chronic chest pain and a high likelihood of CAD 1.
Indications for Myocardial Perfusion Scan
- Evaluating patients with suspected or known coronary artery disease who have intermediate risk
- Unclear stress test results
- When standard exercise stress testing is not feasible
- Patients with chest pain, shortness of breath, or other symptoms suggesting cardiac ischemia
- Patients with baseline ECG abnormalities that make standard stress testing difficult to interpret
- Risk stratification after a heart attack
- Evaluation before major non-cardiac surgery in high-risk patients
- Assessment of revascularization needs
Benefits of Myocardial Perfusion Scan
- Identifies relative myocardial perfusion defects, indicating the presence of myocardial ischemia and/or infarction
- Demonstrates reversibility (ischemia) or irreversibility (infarction) of a myocardial perfusion defect
- Helps distinguish between significant single-vessel and multivessel coronary arterial obstructions
- Provides information on the magnitude of the abnormality and the presence of high-risk findings, assisting in clinical decision making
Recent Guidelines and Studies
- The 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guideline for the evaluation and diagnosis of chest pain recommends stress SPECT MPI as a useful test for diagnosing myocardial ischemia in intermediate-risk patients with acute chest pain and no known CAD 1.
- A 2022 study published in the Journal of the American College of Radiology found that stress SPECT MPI is useful for estimating the extent and severity of coronary stenosis, which has relevance for prognosis, choice among therapeutic options, and advisability of performing coronary arteriography 1.
From the Research
Indications for Myocardial Perfusion Scan
The following are indications for ordering a myocardial perfusion scan:
- Diagnosis of coronary artery disease (CAD) in patients with intermediate pretest likelihood of disease 2, 3
- Risk stratification assessment in patients with suspected or known CAD 2, 3
- Treatment decision making in patients with CAD 2, 3
- Evaluation of myocardial ischemia, scars, stunning, and viable hibernating myocardium 3
- Assessment of left ventricular volume, global and regional function by electrocardiography (ECG)-gated acquisition 3
Patient Selection
Myocardial perfusion scan is recommended for:
- Patients with intermediate pre-test probability of CAD or with a history of ischemic cardiomyopathy 3
- Patients with poor exercise capacity, abnormal resting electrocardiography, or an intermediate or high probability of CAD 2
- Patients who are incapable of performing adequate exercise, where pharmacologic myocardial perfusion SPECT with adenosine or dipyridamole can be used as an alternative to treadmill stress 4
Diagnostic Accuracy
The diagnostic accuracy of myocardial perfusion imaging is:
- Similar for SPECT, PET, and cardiac magnetic resonance 2
- Improved when combined with anatomical tests such as coronary CT angiography 5
- Valuable for prognostication, particularly when assessing myocardial blood flow with PET 2
Clinical Application
Myocardial perfusion SPECT is widely used in clinical practice due to its: