Professional Statements and Societal Positions Guidelines
Practice Guidelines and Position Statements
Guidelines or position statements will be considered for inclusion in ‘Supplemental Information' if they were issued by, or jointly by, a US professional society, an international society with US representation, or National Institute for Health and Care Excellence (NICE). Priority will be given to guidelines that are informed by a systematic review, include strength of evidence ratings, and include a description of management of conflict of interest.
American Society for Nuclear Cardiology/Society of Nuclear Medicine and Molecular Imaging
The American Society of Nuclear Cardiology (ASNC) and the Society of Nuclear Medicine and Molecular Imaging (SNMMI) (2016) updated their joint guideline on procedure standards for cardiac PET procedures.51, PET myocardial perfusion imaging is used "to detect physiologically significant coronary artery narrowing to guide clinical management of individuals with known or suspected CAD [coronary artery disease] and those without overt CAD but with cardiovascular risk factors in order to: evaluate the progression of atherosclerosis, determine cause of ischemic symptoms and recommend medical or revascularization therapy, estimate the potential for future adverse events, and improve individual survival." Perfusion defects can be reported through qualitative scoring, semiquantitative scoring systems, or absolute quantification of myocardial blood flow (MBF). The guideline is limited by not providing direct recommendations with associated levels of evidence and strength of recommendations. However, the authors note that "quantitative absolute MBF measurements with PET appear most helpful in:
- individuals without known prior history of cardiac disease who present with symptoms suspicious for myocardial ischemia,
- individuals with known CAD, in whom more specific physiological assessment is desired,
- identifying an increased suspicion for multivessel CAD,
- situations with a disparity between visual perfusion abnormalities and apparently normal coronary angiography, in order to assess possible microvascular dysfunction, and
- heart transplant when there is a question of vasculopathy.
In contrast, there are particular individuals for whom reporting hyperemic blood flow or flow reserve may not add diagnostic value or can be ambiguous or misleading, including:
- individuals post-CABG [coronary artery bypass graft] who can have diffuse reduction on MBF despite patent grafts,
- individuals with large transmural infarcts where resting flow may be severely reduced such that small increases in flow lead to normal or near-normal flow reserve,
- individuals with advanced severe chronic renal dysfunction who likewise often have diffuse coronary disease, and
- individuals with severe LV [left ventricular] dysfunction."
A joint position paper from SNMMI/ASNC (2018) further discussed clinical quantification of MBF. Stress MBF and myocardial reserve flow (MFR) are associated with improved diagnostic sensitivity, but specificity has varied in studies. Treatment guidance noted that "[a]t present there are no randomized data supporting the use of any stress imaging modality for selection of individuals for revascularization or for guidance of medical therapy. Observational data have established a paradigm that individuals with greater degrees of ischemia on relative MPI [myocardial perfusion imaging] are more likely to benefit from revascularization. This paradigm has been conceptually extended to include MFR and stress MBF but has not yet been evaluated prospectively." The following key points were highlighted:
- "Use of stress MBF and MFR for diagnosis is complex, as diabetes, hypertension, age, smoking, and other risk factors may decrease stress MBF and MFR without focal epicardial stenosis.
- Individuals with preserved stress MBF and MFR are unlikely to have high-risk epicardial CAD.
- Preserved stress MBF of more than two (2) mL/min/g and MFR of more than two (2) reliably exclude the presence of high-risk angiographic disease (negative predictive value greater than 95%) and are reasonable to report when used in clinical interpretation.
- A severely decreased global MFR (less than 1.5 mL/min/g) should be reported as a high-risk feature for adverse cardiac events but is not always due to multivessel obstructive disease. The likelihood of multivessel obstructive disease may be refined by examination of the electrocardiogram, regional perfusion, coronary calcification, and cardiac volumes and function.
- Regional decreases in stress MBF (less than 1.5 mL/min/g) and MFR (less than 1.5) in a vascular territory may indicate regional flow-limiting disease."
The position paper additionally calls for further data on quantifying MBF and MFR in suspected or established CAD: "[t]hese methods are at the cusp of translation to clinical practice. However, further efforts are necessary to standardize measures across laboratories, radiotracers, equipment, and software. Most critically, data are needed supporting improved clinical outcomes when treatment selection is based on these measures."
A joint expert consensus document from SNMMI/ASNC (2017) covered the role of F-18 FDG PET for cardiac sarcoidosis detection and therapy monitoring. The document discusses the need to integrate multiple sources of data, including F-18 FDG PET in some cases, to diagnose cardiac sarcoidosis. The following outlines clinical scenarios where cardiac PET may be useful in individuals with suspected or known disease. Associated levels of evidence and strength of recommendations were not provided with these scenarios.
- "Individuals with histologic evidence of extraCS [extracardiac sarcoidosis], and abnormal screening for CS [cardiac sarcoidosis], defined as one or more of following:
- Abnormal electrocardiographic findings of complete left or right bundle branch block or presence of unexplained pathologic Q waves in two or more leads
- Echocardiographic findings of regional wall motion abnormality, wall aneurysm, basal septum thinning, or LVEF [left ventricular ejection fraction] less than or equal to 50%
- Holter findings of sustained or nonsustained ventricular tachycardia
- Cardiac MRI findings suggestive of CS
- Unexplained palpitations or syncope
- Young individuals (less than 60 y) with unexplained, new onset, significant conduction system disease (such as sustained second- or third-degree atrioventricular block)
- Individuals with idiopathic sustained ventricular tachycardia, defined as not fulfilling any of the following criteria:
- Typical outflow tract ventricular tachycardia
- Fascicular ventricular tachycardia
- Ventricular tachycardia secondary to other structural heart disease (coronary artery disease or any cardiomyopathy other than idiopathic)
- Individuals with proven CS as adjunct to follow response to treatment"
American College of Cardiology et al
The American College of Cardiology (ACC) Foundation and American Heart Association (AHA) (2009) collaborated with six (6) other imaging societies to develop Appropriate Use Criteria for cardiac radionuclide imaging.53, Their report stated:
"...use of cardiac radionuclide imaging for diagnosis and risk assessment in intermediate- and high-risk individuals with coronary artery disease (CAD) was viewed favorably, while testing in low-risk individuals, routine repeat testing, and general screenings in certain clinical scenarios were viewed less favorably. Additionally, use for perioperative testing was found to be inappropriate except for high selected groups of individuals."
American College of Radiology
The American College of Radiology (ACR) Appropriateness Criteria (2016) considered both SPECT and PET to be appropriate for the evaluation of individuals with a high probability of CAD.54, The ACR indicated that PET perfusion imaging has advantages over SPECT, including higher spatial and temporal resolution. Routine performance of both PET and SPECT are unnecessary. The 2017 update55, stated:
"Hybrid PET scanners use CT [computed tomography] for attenuation correction (PET/CT) following completion of the PET study. By coupling the PET perfusion examination findings to a CCTA [cardiac computed tomographic angiography], PET/CT permits the fusion of anatomic coronary arterial and functional (perfusion) myocardial information and enhances diagnostic accuracy. The fused examinations can accurately measure the atherosclerotic burden and identify the hemodynamic functional significance of coronary stenosis. The results of the combined examinations can more accurately identify individuals for revascularization."
The ACR Appropriateness Criteria (2018) also recommended PET for the evaluation of individuals with chronic chest pain that is unlikely to be from a noncardiac etiology and low-to-intermediate probability of CAD.56,
The ACR does not recommend PET for individuals with acute nonspecific chest pain who have a low probability of CAD57, or for asymptomatic individuals at risk for CAD.58,
Society of Nuclear Medicine and Molecular Imaging, et al
A joint guidance from SNMMI/ACC/ASNC/AHA/Canadian Cardiovascular Society/Canadian Society of Cardiovascular Nuclear and CT Imaging/Society of Cardiovascular CT/American College of Physicians/European Association of Nuclear Medicine (2020) developed appropriate use criteria for PET myocardial perfusion imaging for the most common scenarios encountered.59, The summary of recommendations for individuals with suspected or known CAD with symptoms state that rest-stress PET myocardial perfusion imaging is appropriate for those with an intermediate-to-high pretest likelihood of disease regardless of whether the individual has a normal electrocardiogram result or can (or cannot) exercise. In ordering tests, both the diagnostic accuracy and prognostic value are considerations. In individuals with a low pretest likelihood of disease, PET myocardial perfusion imaging is not appropriate. The document also stated: "[o]nly a few studies describe the effects of PET MPI [myocardial perfusion imaging] perfusion and flow quantification on the clinical decision-making process and clinical outcome, which thus warrants further evaluation in well-designed and large-scale clinical trials."
For the evaluation of individuals with known or suspected cardiac sarcoidosis, "rest PET MPI [myocardial perfusion imaging] was rated by the experts as appropriate in individuals undergoing assessment of myocardial inflammation with 18F-FDG PET at baseline and during reevaluation for response to therapy or recurrent inflammation.59, In contrast, stress MPI was rated as may be appropriate in the evaluation of individuals with suspected sarcoidosis who have not been previously evaluated for CAD, and as rarely appropriate in individuals with suspected sarcoidosis who have been previously evaluated for CAD."
For the evaluation of individuals with known or suspected cardiac sarcoidosis, "rest PET MPI [myocardial perfusion imaging] was rated by the experts as appropriate in individuals undergoing assessment of myocardial inflammation with 18F-FDG PET at baseline and during reevaluation for response to therapy or recurrent inflammation.59, In contrast, stress MPI was rated as may be appropriate in the evaluation of individuals with suspected sarcoidosis who have not been previously evaluated for CAD, and as rarely appropriate in individuals with suspected sarcoidosis who have been previously evaluated for CAD."
