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Computed tomographic evaluation of myocardial ischemia.

ABSTRACT: Myocardial ischemia is caused by a mismatch between myocardial oxygen consumption and oxygen delivery in coronary artery disease (CAD). Stratification and decision-making based on ischemia improves the prognosis in patients with CAD. Non-invasive tests used to evaluate myocardial ischemia include stress electrocardiography, echocardiography, single-photon emission computed tomography, and magnetic resonance imaging. Invasive fractional flow reserve is considered the reference standard for assessment of the hemodynamic significance of CAD. Computed tomography (CT) angiography has emerged as a first-line imaging modality for evaluation of CAD, particularly in the population at low to intermediate risk, because of its high negative predictive value; however, CT angiography does not provide information on the hemodynamic significance of stenosis, which lowers its specificity. Emerging techniques, e.g., CT perfusion and CT-fractional flow reserve, help to address this limitation of CT, by determining the hemodynamic significance of coronary artery stenosis. CT perfusion involves acquisition during the first pass of contrast medium through the myocardium following pharmacological stress. CT-fractional flow reserve uses computational fluid dynamics to model coronary flow, pressure, and resistance. In this article, we review these two functional CT techniques in the evaluation of myocardial ischemia, including their principles, technology, advantages, limitations, pitfalls, and the current evidence.

SUBMITTER: Tanabe Y

PROVIDER: S-EPMC7186254 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundCoronary computed tomography angiography (CCTA) allows for non-invasive assessment of obstructive coronary artery disease (CAD) beyond measures of stenosis severity alone. This assessment includes atherosclerotic plaque characteristics (APCs) and calculation of fractional flow reserve (FFR) from CCTA (FFRCT). Similarly, stress imaging by myocardial perfusion scintigraphy (MPS) provides vital information. To date, the diagnostic performance of integrated CCTA assessment versus integrated MPS assessment for diagnosis of vessel-specific ischemia remains underexplored.MethodsCREDENCE will enroll adult individuals with symptoms suspicious of CAD referred for non-emergent invasive coronary angiography (ICA), but without known CAD. All participants will undergo CCTA, MPS, ICA and FFR. FFR will be performed for lesions identified at the time of ICA to be ≥40 and <90 % stenosis, or those clinically indicated for evaluation. Study analyses will focus on diagnostic performance of CCTA versus MPS against invasive FFR reference standard. An integrated stenosis-APC-FFRCT metric by CCTA for vessel-specific ischemia will be developed from derivation cohort and tested against a validation cohort. Similarly, integrated metric by MPS for vessel-specific ischemia will be developed, validated and compared. An FFR value of ≤0.80 will be considered as ischemia causing. The primary endpoint will be the diagnostic accuracy of vessel territory-specific ischemia of integrated stenosis-APC-FFRCT measure by CCTA, compared with perfusion or perfusion-myocardial blood flow stress imaging testing, against invasive FFR.DiscussionCREDENCE will determine the performance of integrated CCTA metric compared to integrated MPS measure for diagnosis of vessel-specific ischemia. If proven successful, this study may reduce the number of missed diagnoses and help to optimally predict ischemia-causing lesions.Trial registrationClinicalTrials.gov, NCT02173275 . Registered on June 23, 2014.

Project description:ImportanceStress imaging has been the standard for diagnosing functionally significant coronary artery disease. It is unknown whether novel, atherosclerotic plaque measures improve accuracy beyond coronary stenosis for diagnosing invasive fractional flow reserve (FFR) measurement.ObjectiveTo compare the diagnostic accuracy of comprehensive anatomic (obstructive and nonobstructive atherosclerotic plaque) vs functional imaging measures for estimating vessel-specific FFR.Design, setting, and participantsControlled clinical trial of diagnostic accuracy with a multicenter derivation-validation cohort of patients referred for nonemergent invasive coronary angiography. A total of 612 patients (64 [10] years; 30% women) with signs and symptoms suggestive of myocardial ischemia from 23 sites were included. Patients were recruited from 2014 to 2017. Data analysis began in August 2018.InterventionsPatients underwent invasive coronary angiography with measurement of invasive FFR, coronary computed tomographic angiography (CCTA) quantification of atherosclerotic plaque and FFR by CT (FFR-CT), and semiquantitative scoring of rest/stress myocardial perfusion imaging (by magnetic resonance, positron emission tomography, or single photon emission CT). Multivariable generalized linear mixed models were derived and validated calculating the area under the receiver operating characteristics curve.Main outcomes and measuresThe primary end point was invasive FFR of 0.80 or less.ResultsOf the 612 patients, the mean (SD) age was 64 (10) years, and 426 (69.9%) were men. An invasive FFR of 0.80 or less was measured in 26.5% of 1727 vessels. In the derivation cohort, CCTA vessel-specific factors associated with FFR 0.80 or less were stenosis severity, percentage of noncalcified atheroma volume, lumen volume, the number of lesions with high-risk plaque (≥2 of low attenuation plaque, positive remodeling, napkin ring sign, or spotty calcification), and the number of lesions with stenosis greater than 30%. Fractional flow reserve-CT was not additive to this model including stenosis and atherosclerotic plaque. Significant myocardial perfusion imaging predictors were the summed rest and difference scores. In the validation cohort, the areas under the receiver operating characteristic curve were 0.81 for CCTA vs 0.67 for myocardial perfusion imaging (P < .001).Conclusions and relevanceA comprehensive anatomic interpretation with CCTA, including quantification of obstructive and nonobstructive atherosclerotic plaque, was superior to functional imaging in the diagnosis of invasive FFR. Comprehensive CCTA measures improve prediction of vessel-specific coronary physiology more so than stress-induced alterations in myocardial perfusion.Trial registrationClinicalTrials.gov Identifier: NCT02173275.

Project description:BackgroundMicrovascular dysfunction (MVD) is a potential cause of chest pain in younger individuals. The authors hypothesized that nonelderly patients referred for computed tomographic angiography (CTA) but without significant stenosis would have a high prevalence of MVD by myocardial contrast echocardiography (MCE). Secondary aims were to test whether the presence of nonobstructive coronary artery disease (CAD) or reduced brachial flow-mediated dilation (FMD) predicted MVD.MethodsSubjects ≤60 years of age undergoing CTA were recruited if they had either no evidence of coronary plaque or evidence of mild CAD (<50% stenosis) and at least one high-risk plaque feature. Subjects underwent quantitative perfusion imaging using MCE at rest and during regadenoson vasodilator stress. MVD was defined as global or segmental delay of microvascular refill (≥2 sec) during regadenoson. FMD of the brachial artery was also performed.ResultsOf the 29 patients in whom MCE could be performed, 12 (41%) had MVD. These subjects, compared with those with normal microvascular function, had lower hyperemic perfusion (mean, 236 ± 68 vs 354 ± 161 intensity units/sec; P = .02) and microvascular flux rate (mean, 1.6 ± 0.4 vs 2.5 ± 0.9 sec-1; P = .002) on quantitative MCE. The degree of FMD was not significantly different in those with or without MVD (mean, 11 ± 4% vs 9 ± 4%; P = .32), and there was a poor correlation between results on stress MCE and FMD. Only eight of the 29 subjects were classified as having nonobstructive CAD. There were no groupwise differences in the prevalence of MVD function in those with versus without CAD (43% vs 38% for negative and positive findings on CTA, respectively, P = .79).ConclusionsMVD is a common finding in the nonelderly population referred for CTA for evaluation of possible CAD but without obstructive stenosis. Neither the presence of noncritical atherosclerotic disease nor abnormal FMD increases the likelihood for detecting MVD in this population.

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Computed tomographic evaluation of myocardial ischemia.

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