Non-Invasive Imaging in Coronary Syndromes: Recommendations of The European Association of Cardiovascular Imaging and the American Society of Echocardiography, in Collaboration with The American Society of Nuclear Cardiology, Society of Cardiovascular Computed Tomography, and Society for Cardiovascular Magnetic Resonance

Abstract

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This activity is free for ASE Members, and $25 for nonmembers. •Preamble•Background∘Definition and pathophysiology of coronary artery disease—basic concepts relevant to non-invasive imaging∘Epidemiology—focused towards the pre-test probability of CAD and Bayesian predictive models∘Clinical role of imaging and current guidelines for chronic coronary syndromes∘Clinical role of imaging and current guidelines for acute coronary syndromes•Overview of imaging methods in CAD∘Anatomical vs. functional imaging∘Echocardiography∘Computed tomography∘SPECT and PET nuclear imaging∘Cardiovascular magnetic resonance•Diagnosis of acute coronary syndromes and the role of imaging∘Left ventricular function assessment∘Myocardial perfusion imaging∘Coronary artery anatomy∘Myocardial scar and Edema assessment∘Differential diagnosis in acute chest pain∘Risk stratification after revascularization•Diagnosis of chronic coronary syndromes—the role of imaging∘Left ventricular function assessment∘Myocardial ischemia assessment∘Assessment of coronary artery stenosis∘Myocardial viability and scar assessment∘Risk stratification in chronic coronary syndromes•Conclusions and future directions Coronary artery disease (CAD) is one of the major causes of mortality and morbidity worldwide, with a high socioeconomic impact.1Townsend N. Nichols M. Scarborough P. Rayner M. Cardiovascular disease in Europe—epidemiological update 2015.Eur Heart J. 2015; 36: 2696-2705Google Scholar Non-invasive imaging modalities play a fundamental role in the evaluation and management of patients with known or suspected CAD. Imaging endpoints have served as surrogate markers in many observational studies and randomized clinical trials that evaluated the benefits of specific therapies for CAD.2Bates R.E. Omer M. Abdelmoneim S.S. Arruda-Olson A.M. Scott C.G. Bailey K.R. et al.Impact of stress testing for coronary artery disease screening in asymptomatic patients with diabetes mellitus: a community-based study in Olmsted County, Minnesota.Mayo Clin Proc. 2016; 91: 1535-1544Google Scholar A number of guidelines and recommendations have been published about coronary syndromes by cardiology societies and associations but have not focused on the excellent opportunities with cardiac imaging. The recent European Society of Cardiology (ESC) 2019 guideline on chronic coronary syndromes (CCS) and 2020 guideline on acute coronary syndromes (ACS) in patients presenting with non-ST-segment elevation (NSTE-ACS) highlight the importance of non-invasive imaging in the diagnosis, treatment, and risk assessment of the disease.3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar,4Collet J.-P. Thiele H. Barbato E. Barthélémy O. Bauersachs J. Bhatt D.L. et al.ESC Scientific Document Group 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation.Eur Heart J. 2021; 42: 1289-1367Google Scholar The purpose of the current recommendations is to present the significant role of non-invasive imaging in coronary syndromes in more detail. These recommendations have been developed by the European Association of Cardiovascular Imaging (EACVI) and the American Society of Echocardiography (ASE), in collaboration with the American Society of Nuclear Cardiology, the Society of Cardiovascular Computed Tomography, and the Society for Cardiovascular Magnetic Resonance, all of which have approved the final document. The experts of the writing panel provided declarations of interest forms for all relationships that might be perceived as real or potential sources of conflicts of interest. Myocardial ischemia and infarction caused by epicardial coronary atherosclerosis are the main manifestations of CAD. Stenotic or occluded coronary arteries impair downstream blood flow, reduce myocardial perfusion, cause contractile dysfunction, and ultimately lead to angina or, in acute syndromes, myocardial infarction. Coronary syndromes may have stable periods, but can suddenly lead to an unstable event caused by plaque rupture or erosion. The nature of the disease is progressive, resulting in various clinical presentations—from subclinical to CCS and ACS, all of which are covered in this recommendations paper. The distinctive pathophysiological characteristics of CAD can be evaluated with various imaging modalities such as echocardiography,3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar single-photon emission computed tomography (SPECT), positron emission tomography (PET), cardiac magnetic resonance (CMR), or coronary computed tomography angiography (CTA).5Wolk M.J. Bailey S.R. Doherty J.U. Douglas P.S. Hendel R.C. Kramer C.M. et al.American College of Cardiology Foundation Appropriate Use Criteria Task ForceACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Am Coll Cardiol. 2014; 63: 380-406Google Scholar,6Neumann F.-J. Sousa-Uva M. Ahlsson A. Alfonso F. Banning A.P. Benedetto U. et al.ESC Scientific Document Group 2018 ESC/EACTS Guidelines on myocardial revascularization.Eur Heart J. 2019; 40: 87-165Google Scholar Combining anatomical and functional imaging modalities by either sequential stand-alone tests or hybrid approaches [e.g. SPECT/computed tomography (CT), PET/CT] would allow a more comprehensive characterization of obstructive CAD.7Sicari R. Cortigiani L. The clinical use of stress echocardiography in ischemic heart disease.Cardiovasc Ultrasound. 2017; 15: 7Google Scholar, 8Pontone G. Andreini D. Guaricci A.I. Baggiano A. Fazzari F. Guglielmo M. et al.Incremental diagnostic value of stress computed tomography myocardial perfusion with whole-heart coverage CT scanner in intermediate- to high-risk symptomatic patients suspected of coronary artery disease.JACC Cardiovasc Imaging. 2019; 12: 338-349Google Scholar, 9Douglas P.S. De Bruyne B. Pontone G. Patel M.R. Norgaard B.L. Byrne R.A. et al.1-year outcomes of FFRCT-guided care in patients with suspected coronary disease: the PLATFORM study.J Am Coll Cardiol. 2016; 68: 435-445Google Scholar, 10Maaniitty T. Stenström I. Bax J.J. Uusitalo V. Ukkonen H. Kajander S. et al.Prognostic value of coronary CT angiography with selective PET perfusion imaging in coronary artery disease.JACC Cardiovasc Imaging. 2017; 10: 1361-1370Google Scholar, 11Neglia D. Liga R. Caselli C. Carpeggiani C. Lorenzoni V. Sicari R. et al.EVINCI Study InvestigatorsAnatomical and functional coronary imaging to predict long-term outcome in patients with suspected coronary artery disease: the EVINCI-outcome study.Eur Heart J Cardiovasc Imaging. 2020; 21: 1273-1282Google Scholar When choosing a specific imaging test, one needs to take into consideration the multiple factors that interact in the development of ACS and chronic CAD. The preferred imaging technique to confirm the diagnosis of acute or chronic CAD and guide the treatment will depend on the clinical presentation and characteristics of the patient, the local availability and expertise at the clinical centre. While this document provides a set of recommendations, many situations encountered in daily clinical practice may not be covered. Ultimately, understanding how each imaging modality assesses different aspects of CAD remains critical to deciding which modality would be most helpful in providing optimal care for each patient. This document aims to provide guidance on how to select the optimal imaging approach for individual patients. Age, gender, coronary risk factors, and symptom characteristics are used in clinical practice to estimate the probability of CAD and risk for cardiac events and to identify patients who may benefit from non-invasive testing. The European and American guidelines recommend the Duke clinical score and the revised Diamond and Forrester models as preferred clinical tools to calculate pre-test probability (PTP) of obstructive CAD in symptomatic patients without known coronary syndromes.3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar,12Fihn S.D. Gardin J.M. Abrams J. Berra K. Blankenship J.C. Dallas A.P. et al.Society of Thoracic Surgeons 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, and the American College of Physicians, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons.J Am Coll Cardiol. 2012; 60: e44-164Google Scholar While other scores have been proposed for various other CAD scenarios, it is important to estimate the PTP using any of these clinical scores to optimize cost/benefit and to reduce false results in individual patients. However, all of these models might overestimate the prevalence of CAD, and several studies have suggested that the prevalence of obstructive disease among patients with suspected CAD is lower than previously reported.13Juarez-Orozco L.E. Saraste A. Capodanno D. Prescott E. Ballo H. Bax J.J. et al.Impact of a decreasing pre-test probability on the performance of diagnostic tests for coronary artery disease.Eur Heart J Cardiovasc Imaging. 2019; 20: 1198-1207Google Scholar,14Foldyna B. Udelson J.E. Karády J. Banerji D. Lu M.T. Mayrhofer T. et al.Pretest probability for patients with suspected obstructive coronary artery disease: re-evaluating Diamond-Forrester for the contemporary era and clinical implications: insights from the PROMISE trial.Eur Heart J Cardiovasc Imaging. 2019; 20: 574-581Google Scholar The PTP has therefore recently been reconsidered in CCS.3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar Bayes’ theorem of conditional probability applies to the interpretation of all non-invasive imaging test results, since none has 100% sensitivity or specificity to establish either the anatomical presence of obstructive CAD or the functional presence of ischemia. Based on this theorem, optimal performance of most non-invasive tests occurs when PTP is intermediate. The proportion of false positive results increases as PTP decreases. Conversely, the proportion of false negative results increases as PTP increases. Other significant factors that may affect the diagnostic performance of individual tests are the quality of the exams, acquisition protocols and technology used, adherence to protocol standards, patient compliance, heart rate, and body habitus.3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar,7Sicari R. Cortigiani L. The clinical use of stress echocardiography in ischemic heart disease.Cardiovasc Ultrasound. 2017; 15: 7Google Scholar,15Neglia D. Rovai D. Caselli C. Pietila M. Teresinska A. Aguadé-Bruix S. et al.Detection of significant coronary artery disease by noninvasive anatomical and functional imaging.Circ Cardiovasc Imaging. 2015; 8: e002179Google Scholar Since imaging tests used for the diagnosis of CAD have different performance characteristics, it is common practice to preferentially select tests with high sensitivity in high disease prevalence groups and with high specificity in lower prevalence groups in order to reduce false negative and false positive results, respectively. Hemodynamic significance of coronary stenotic lesions varies according to anatomical location, degree of stenosis, extent and composition of obstructive plaque, amount of subtended myocardium, microvascular integrity, presence of collaterals, myocardial oxygen consumption, and many other factors. Diagnostic testing is most useful and recommended when the likelihood of CCS is intermediate. According to current American and European clinical practice guidelines, patients with intermediate PTP of underlying CAD should undergo initial evaluation with non-invasive anatomical or functional diagnostic tests for the assessment of CAD (Figure 1).3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar,5Wolk M.J. Bailey S.R. Doherty J.U. Douglas P.S. Hendel R.C. Kramer C.M. et al.American College of Cardiology Foundation Appropriate Use Criteria Task ForceACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Am Coll Cardiol. 2014; 63: 380-406Google Scholar Patients with very low PTP may not need evaluation (a positive test would be most likely false positive) and patients with high PTP may need direct coronary visualization with angiography (a negative test would most likely be false negative). The new and reconsidered PTP calculation, however, also permits anatomical or functional diagnostic testing in individual patients with a PTP of 5–15% if considered necessary in certain clinical situations. A resting transthoracic echocardiogram (TTE) is recommended in all patients with a suspicion of CCS for assessment of wall motion and structural abnormalities.3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar The evidence of inducible myocardial ischemia or abnormal perfusion by functional imaging testing, coronary atherosclerosis by coronary CTA, or both, may allow the diagnosis of CAD requiring medical treatment. In cases of either failure of medical therapy to control symptoms or of imaging findings suggesting a high risk of coronary events, invasive coronary angiography (ICA) is indicated to address the possible need for revascularization.3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar,5Wolk M.J. Bailey S.R. Doherty J.U. Douglas P.S. Hendel R.C. Kramer C.M. et al.American College of Cardiology Foundation Appropriate Use Criteria Task ForceACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Am Coll Cardiol. 2014; 63: 380-406Google Scholar,6Neumann F.-J. Sousa-Uva M. Ahlsson A. Alfonso F. Banning A.P. Benedetto U. et al.ESC Scientific Document Group 2018 ESC/EACTS Guidelines on myocardial revascularization.Eur Heart J. 2019; 40: 87-165Google Scholar,16Patel M.R. Bailey S.R. Bonow R.O. Chambers C.E. Chan P.S. Dehmer G.J. et al.ACCF/SCAI/AATS/AHA/ASE/ASNC/HFSA/HRS/SCCM/SCCT/SCMR/STS 2012 appropriate use criteria for diagnostic catheterization: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, Society for Cardiovascular Angiography and Interventions, American Association for Thoracic Surgery, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society of Critical Care Medicine, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Am Coll Cardiol. 2012; 59: 1995-2027Google Scholar Thus, non-invasive functional imaging tests serve not only to diagnose the presence of CAD, but also to guide clinical decision-making, and are preferable in patients with high intermediate PTP. The documentation of ischemia involving more than 10% of left ventricular (LV) myocardium or in a multivessel pattern are relevant hallmarks of high risk,3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar as reducing ischemia may favorably impact symptoms and outcome.17Hachamovitch R. Rozanski A. Shaw L.J. Stone G.W. Thomson L.E.J. Friedman J.D. et al.Impact of ischemia and scar on the therapeutic benefit derived from myocardial revascularization vs. medical therapy among patients undergoing stress-rest myocardial perfusion scintigraphy.Eur Heart J. 2011; 32: 1012-1024Google Scholar,18Shaw L.J. Berman D.S. Maron D.J. Mancini G.B.J. Hayes S.W. Hartigan P.M. et al.Optimal medical therapy with or without percutaneous coronary intervention to reduce ischemic burden: results from the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial nuclear substudy.Circulation. 2008; 117: 1283-1291Google Scholar Coronary CTA is the preferred test in patients with the lowest intermediate range of clinical likelihood of CCS, no previous diagnosis of CAD, and characteristics associated with a high likelihood of good image quality, based on its high negative predictive value (the ability to exclude significant CAD).3Knuuti J. Wijns W. Saraste A. Capodanno D. Barbato E. Funck-Brentano C. et al.2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes: the Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC).Eur Heart J. 2020; 41: 407-477Google Scholar Functional testing with imaging is preferred in patients with a higher likelihood of CCS, known CAD, high burden of calcified atherosclerosis on prior CT imaging, and in patients who are not ideal candidates for coronary CTA (Figure 1). Coronary CTA may also be utilized in patients with chronic chest pain syndrome and equivocal findings with functional imaging. Conversely, functional testing with imaging may be performed in patients with intermediate stenoses on coronary CTA when the results of these tests may lead to changes in patient management (e.g. medical vs. revascularization strategy) (Figure 2).11Neglia D. Liga R. Caselli C. Carpeggiani C. Lorenzoni V. Sicari R. et al.EVINCI Study InvestigatorsAnatomical and functional coronary imaging to predict long-term outcome in patients with suspected coronary artery disease: the EVINCI-outcome study.Eur Heart J Cardiovasc Imaging. 2020; 21: 1273-1282Google Scholar Recently, evaluation of fractional flow reserve (FFR) by CTA has offered the potential to obtain anatomic and functional information from a single exam. Anatomic testing can be useful when a functional test is equivocal or uninterpretable, and vice versa. Radiation risks associated with CT or nuclear imaging with contrast agents should be considered when choosing a specific exam and weighed against alternate procedures and the risk of missing a diagnosis.19Knuuti J. Bengel F. Bax J.J. Kaufmann P.A. Le Guludec D. Perrone Filardi P. et al.Risks and benefits of cardiac imaging: an analysis of risks related to imaging for coronary artery disease.Eur Heart J. 2014; 35: 633-638Google Scholar All efforts are recommended to reduce imaging-related risks by using adequate protocols, proper technologies, and avoiding useless/redundant procedures.19Knuuti J. Bengel F. Bax J.J. Kaufmann P.A. Le Guludec D. Perrone Filardi P. et al.Risks and benefits of cardiac imaging: an analysis of risks related to imaging for coronary artery disease.Eur Heart J. 2014; 35: 633-638Google Scholar,20Gimelli A. Achenbach S. Buechel R.R. Edvardsen T. Francone M. Gaemperli O. et al.EACVI Scientific Documents CommitteeStrategies for radiation dose reduction in nuclear cardiology and cardiac computed tomography imaging: a report from the European Association of Cardiovascular Imaging (EACVI), the Cardiovascular Committee of European Association of Nuclear Medicine (EANM), and the European Society of Cardiovascular Radiology (ESCR).Eur Heart J. 2018; 39: 286-296Google Scholar In about 20% of all patients with stable symptoms and evidence of ischemia, obstructive epicardial disease will be absent (ischemia and non-obstructive coronary artery disease, INOCA); thus, the apparent ischemia may be due to microvascular disease or non-cardiac causes. Whether the endothelium, the smooth muscle cells in the microvasculature or both are the culprits of such disease is unknown. Nevertheless, both are possibly associated with cardiovascular risk factors or structural myocardial abnormalities such as hypertrophy, dilatation, or a mix of them.21Liga R. Marini C. Coceani M. Filidei E. Schlueter M. Bianchi M. et al.Structural abnormalities of the coronary arterial wall–in addition to luminal narrowing–affect myocardial blood flow reserve.J Nucl Med. 2011; 52: 1704-1712Google Scholar, 22Driessen R.S. Stuijfzand W.J. Raijmakers P.G. Danad I. Min J.K. Leipsic J.A. et al.Effect of plaque burden and morphology on myocardial blood flow and fractional flow reserve.J Am Coll Cardiol. 2018; 71: 499-509Google Scholar, 23Crea F. Camici P.G. Bairey Merz C.N. Coronary microvascular dysfunction: an update.Eur Heart J. 2014; 35: 1101-1111Google Scholar Recognition of these conditions by non-invasive imaging is relevant for risk stratification even if the clinical impact of pharmacological treatment is not yet defined23Crea F. Camici P.G. Bairey Merz C.N. Coronary microvascular dysfunction: an update.Eur Heart J. 2014; 35: 1101-1111Google Scholar,24Neglia D. Michelassi C. Trivieri M.G. Sambuceti G. Giorgetti A. Pratali L. et al.Prognostic role of myocardial blood flow impairment in idiopathic left ventricular dysfunction.Circulation. 2002; 105: 186-193Google Scholar (Figure 3). Transthoracic echocardiography, using either fully equipped units or point-of-care ultrasound systems, should be available to all emergency rooms and should be performed and interpreted by trained expert operators, in all patients referred for chest pain, except in limited situations such as ST-elevation myocardial infarction (STEMI) where imaging would delay reperfusion.4Collet J.-P. Thiele H. Barbato E. Barthélémy O. Bauersachs J. Bhatt D.L. et al.ESC Scientific Document Group 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation.Eur Heart J. 2021; 42: 1289-1367Google Scholar Bedside echocardiography is beneficial when complications are suspected or when an alternative diagnosis is considered (Figure 4). Alternative diagnoses include aortic dissection, pericarditis with or without pericardial effusion, hypertrophic cardiomyopathy, mitral valve prolapse, or right ventricular (RV) dilatation that could be suggestive of acute pulmonary embolism (PE). In patients presenting with acute chest pain syndromes, European guidelines and American appropriate use criteria recognize the value of coronary CTA or functional testing as an alternative to ICA to rule out ACS in patients at very low or low risk for ACS.4Collet J.-P. Thiele H. Barbato E. Barthélémy O. Bauersachs J. Bhatt D.L. et al.ESC Scientific Document Group 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation.Eur Heart J. 2021; 42: 1289-1367Google Scholar This includes patients with indeterminate electrocardiogram (ECG) changes, negative troponins, and no recent chest pain. Functional imaging in this situation has higher accuracy and is clearly favored over a stress ECG. This strategy is, however, not recommended in STEMI or NSTE-ACS with high-risk features, where prompt ICA should be pursued [primary percutaneous coronary intervention (PCI) for STEMI, within 24 h for NSTE-ACS].4Collet J.-P. Thiele H. Barbato E. Barthélémy O. Bauersachs J. Bhatt D.L. et al.ESC Scientific Document Group 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation.Eur Heart J. 2021; 42: 1289-1367Google Scholar,5Wolk M.J. Bailey S.R. Doherty J.U. Douglas P.S. Hendel R.C. Kramer C.M. et al.American College of Cardiology Foundation Appropriate Use Criteria Task ForceACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons.J Am Coll Cardiol. 2014; 63: 380-406Google Scholar,25Rybicki F.J. Udelson J.E. Peacock W.F. Goldhaber S.Z. Isselbacher E.M. Kazerooni E. et al.2015 ACR/ACC/AHA/AATS/ACEP/ASNC/NASCI/SAEM/SCCT/SCMR/SCPC/SNMMI/STR/STS appropriate utilization of cardiovascular imaging in emergency department patients with chest pain: a joint document of the American College of Radiology Appropriateness Criteria Committee and the American College of Cardiology Appropriate Use Criteria Task Force.J Am Coll Cardiol. 2016; 67: 853-879Google Scholar Non-invasive imaging methods used to evaluate patients with known or suspected CAD rely on assessing: (i) presence and anatomic severity of stenosis, (ii) abnormal flow in epicardial arteries, (iii) abnormal myocardial perfusion, or (iv) abnormal myocardial contractility. LV regional assessment of perfusion or systolic function is important for the detection of CAD, characterizing the spatial distribution of ischemia (i.e. coronary territories involved), and for identifying patients who are at high risk for adverse events and may benefit from revascularization. By convention, regional myocardial involvement is described using either a 16-segment model (the LV is divided into six segments at the base and mid-level, and four at the apex) or a 17-segment model (including the additional area of an ‘apical cap’), which was added to standardize reporting among imaging modalities. A wall motion score can be derived by assigning each segment a numerical value (e.g. one for normal/hyperkinesis, two for hypokinesis, three for akinesis, four for dyskinesis, and five for aneurysm) and computing a mean value for all se