Myocardial Perfusion Imaging Recommendations for Suspected Coronary Artery Disease
Myocardial perfusion imaging (MPI) is recommended for patients with moderate to high pre-test likelihood (>15-85%) of obstructive coronary artery disease (CAD) to diagnose myocardial ischemia and estimate the risk of major adverse cardiac events. 1
Patient Selection Based on Pre-Test Likelihood
For patients with moderate or high pre-test likelihood (>15-85%) of obstructive CAD, SPECT or preferably PET myocardial perfusion imaging is recommended to diagnose and quantify myocardial ischemia and/or scar, estimate risk of major adverse cardiac events, and quantify myocardial blood flow (with PET) 1
For patients with low to moderate pre-test likelihood (>5-50%) of obstructive CAD, coronary computed tomography angiography (CCTA) is the preferred initial diagnostic test 1
For patients with very high pre-test likelihood (>85%) of obstructive CAD, severe symptoms refractory to medical therapy, angina at low level of exercise, or high event risk, invasive coronary angiography is recommended 1
Specific Clinical Scenarios for MPI
MPI is indicated when another non-invasive test is non-diagnostic in patients with low or moderate pre-test likelihood of CAD 1
In patients selected for PET or SPECT MPI, measurement of coronary artery calcium score from unenhanced chest CT (used for attenuation correction) is recommended to improve detection of both non-obstructive and obstructive CAD 1
For patients with de novo symptoms highly suggestive of obstructive CAD occurring at low level of exercise, invasive coronary angiography with view toward revascularization is recommended as first diagnostic test after clinical assessment 1
Technical Considerations for MPI
Technetium-99m labeled agents (sestamibi, tetrofosmin) are preferred over thallium-201 due to improved image resolution, higher count density, and more favorable dosimetry 1
The diagnostic accuracy of stress SPECT MPI for detecting angiographically significant CAD is high with sensitivity of 87-89% and specificity of 73-75% 1
A normal stress SPECT MPI in patients with intermediate to high likelihood of CAD predicts a very low rate of cardiac death or nonfatal myocardial infarction (1% per year) 1
Contraindications and Precautions
Absolute contraindications for MPI include high-risk unstable angina, complicated acute coronary syndrome or acute myocardial infarction within 2 days, significant arrhythmias, and significant hypotension (systolic blood pressure <90 mmHg) 2
Contraindications specific to vasodilator stress agents include known or suspected bronchoconstrictive or bronchospastic disease, and use of dipyridamole or methylxanthines within 12 hours before the test 2
Pharmacologic induction of cardiovascular stress may be associated with serious adverse events such as myocardial infarction, arrhythmia, hypotension, bronchoconstriction, and cerebrovascular events 3
Hybrid Imaging Approaches
Hybrid SPECT/CCTA combines anatomic information from CT with functional perfusion evidence from SPECT, resulting in enhanced diagnostic accuracy (sensitivity 96%, specificity 95%) compared with SPECT (93%, 79%) or CCTA (98%, 62%) alone 1
There is high agreement (92%) on the necessity of revascularization in treatment decisions based on hybrid SPECT/CCTA versus SPECT and coronary angiography alone 1
Alternative Imaging Modalities
In patients with suspected CAD and moderate or high pre-test likelihood of obstructive CAD, cardiac magnetic resonance (CMR) perfusion imaging is recommended to diagnose and quantify myocardial ischemia and/or scar and estimate risk of major adverse cardiac events 1
Stress echocardiography is recommended for patients with suspected CAD and moderate or high pre-test likelihood of obstructive CAD to diagnose myocardial ischemia and estimate risk of major adverse cardiac events 1
When selecting between imaging modalities, consider local expertise, availability, patient characteristics that influence test performance, and radiation exposure concerns, especially in younger patients 1, 2