Physiological Significance Of Coronary Stenosis Research Articles

The diagnostic performance of AccuFFRangio for evaluating coronary artery stenosis under different computational conditions.

A computational method (AccuFFrangio) based on invasive coronary angiography (ICA) and computational fluid dynamics (CFD) to calculate fractional flow reserve (FFR) without a pressure wire has been devised to clarify the physiological significance of coronary stenosis. This study aimed to evaluate the diagnostic performance of AccuFFRangio computation under different boundary conditions and vessel reconstruction approaches. Consecutive patients with stable angina pectoris who underwent ICA and FFR assessment from 2 centers were analyzed retrospectively. Using wire-based FFR as the reference standard, the diagnostic performances of AccuFFRangio and its variations were evaluated and compared. The calculation of AccuFFRangio involves several key boundary conditions, including patient-specific aortic pressure, contrast flow velocity derived from the thrombolysis in myocardial infarction (TIMI) frame count method, and vessel reconstruction based on 2 angiographic views. We considered the following 3 variations: (I) a fixed aortic pressure [fixed pressure AccuFFRangio (pAccuFFRangio)], (II) an empirical hyperemic velocity [fixed velocity AccuFFRangio (vAccuFFRangio)], and (III) vessel reconstruction using a single angiographic view [single view AccuFFRangio (sAccuFFRangio)]. A total of 230 patients with 230 vessels were included in the final analysis. The accuracy for standard AccuFFRangio, pAccuFFRangio, vAccuFFRangio, and sAccuFFRangio was 93.91%, 86.52%, 81.74%, and 83.48%, respectively; the sensitivity was 90.74%, 51.85%, 83.33%, and 46.30%, respectively; the specificity was 94.89%, 97.16%, 81.25%, and 94.89%, respectively; and the area under the receiver operating characteristic curve was 0.971, 0.928, 0.892, and 0.870, respectively. The comparison suggested that the overall performance of the standard AccuFFRangio was superior to other variations and had the highest accuracy among all the cases.

Evolving Developments in Cardiac CT.

In this review, the authors describe some of the latest cardiac CT advances in the evaluation of cardiovascular disease. This includes automated coronary plaque quantification and subtyping, and cardiac CT fractional flow reserve and CT perfusion as techniques to noninvasively assess the physiologic significance of coronary stenosis. The authors also focus on noncoronary applications involving the expanding role of cardiac CT in structural heart disease interventions. Developments in cardiac CT for the evaluation of diffuse myocardial fibrosis and infiltrative cardiomyopathy and for functional analysis of myocardial contractile dysfunction are discussed. Finally, the authors review studies evaluating photon-counting CT in cardiac disease.

Impact of intracoronary assessments on revascularization decisions: A contemporary evaluation.

To investigate the real-world implementation of intracoronary assessment (ICA) techniques and evaluate their impact on clinical decisions regarding the management of coronary artery disease (CAD) in contemporary practice. Coronary angiogram is the gold standard used to diagnose vessel stenosis and guide percutaneous coronary intervention (PCI); however, it is limited by its two-dimensional imaging capabilities. ICA techniques like intravascular ultrasound and optical coherence tomographycapture the vessel in three-dimensionalimages. Comparatively, fractional flow reserveprovides information on the physiologic significance of coronary stenosis. Both techniques may improve PCI outcomes if they routinely change physician behavior. Patients who underwent ICA between August 2015 and March 2020 were included in the study. The primary outcome was the clinical impact of ICA on physician clinical decision making of a stenotic vessel. The secondary outcome was the clinical changes that occurred following ICA. A total of 1135 patients were included in the study. Physiologic assessment (PA) and image assessment (IA) were performed in 61.4% and 38.6% respectively. Management plans were changed in 38.1% and 23.9% of patients who received PA and IA. Over half of the management change resulted in physicians deciding to not intervene on the stenotic vessel. One-year outcome of these decisions showed no significant increase in major adverse cardiac events (hazard ratio[HR], 0.68; 95% confidence interval [CI], 0.40-1.15; p = 0.15) or unplanned revascularization (HR, 0.78; 95% CI, 0.35-1.74; p = 0.55) suggesting reliance on PA/IA data did not increase risk. Selected ICA alters physician management of CAD in one-third of patients being evaluated for revascularization-typically leading to fewer interventions. All cause death is numerally lower in patients that received a change in management. However, the 1-year outcome of these altered decisions does not appear to be significantly different.

Risk Stratification in Acute Coronary Syndrome by Comprehensive Morphofunctional Assessment With Optical Coherence Tomography.

Artificial intelligence enables simultaneous evaluation of plaque morphology and computational physiology from optical coherence tomography (OCT). This study sought to appraise the predictive value of major adverse cardiovascular events (MACE) by combined plaque morphology and computational physiology. A total of 604 patients with acute coronary syndrome who underwent OCT imaging in≥1 nonculprit vessel during index coronary angiography were retrospectively enrolled. A novel morphologic index, named the lipid-to-cap ratio (LCR), and a functional parameter to evaluate the physiologic significance of coronary stenosis from OCT, namely, the optical flow ratio (OFR), were calculated from OCT, together with classical morphologic parameters, like thin-cap fibroatheroma (TCFA) and minimal lumen area. The 2-year cumulative incidence of a composite of nonculprit vessel-related cardiac death, cardiac arrest, acute myocardial infarction, and ischemia-driven revascularization (NCV-MACE) at 2 years was 4.3%. Both LCR (area under the curve [AUC]: 0.826; 95%CI: 0.793-0.855) and OFR (AUC: 0.838; 95%CI: 0.806-0.866) were superior to minimal lumen area (AUC: 0.618; 95%CI: 0.578-0.657) in predicting NCV-MACE at 2 years. Patients with both an LCR of >0.33 and an OFR of≤0.84 had significantly higher risk of NCV-MACE at 2 years than patients in whom at least 1 of these 2 parameters was normal (HR: 42.73; 95%CI: 12.80-142.60; P< 0.001). The combination of thin-cap fibroatheroma and OFR also identified patients at higher risk of future events (HR: 6.58; 95%CI: 2.83-15.33; P< 0.001). The combination of LCR with OFR permits the identification of a subgroup of patients with 43-fold higher risk of recurrent cardiovascular events in the nonculprit vessels after acute coronary syndrome.

Robotics, imaging, and artificial intelligence in the catheterisation laboratory.

The catheterisation laboratory today combines diagnosis and therapeutics, through various imaging modalities and a prolific list of interventional tools, led by balloons and stents. In this review, we focus primarily on advances in image-based coronary interventions. The X-ray images that are the primary modality for diagnosis and interventions are combined with novel tools for visualisation and display, including multi-imaging co-registration modalities with three- and four-dimensional presentations. Interpretation of the physiologic significance of coronary stenosis based on prior angiographic images is being explored and implemented. Major efforts to reduce X-ray exposure to the staff and the patients, using computer-based algorithms for image processing, and novel methods to limit the radiation spread are being explored. The use of artificial intelligence (AI) and machine learning for better patient care requires attention to universal methods for sharing and combining large data sets and for allowing interpretation and analysis of large cohorts of patients. Barriers to data sharing using integrated and universal protocols should be overcome to allow these methods to become widely applicable. Robotic catheterisation takes the physician away from the ionising radiation spot, enables coronary angioplasty and stenting without compromising safety, and may allow increased precision. Remote coronary procedures over the internet, that have been explored in virtual and animal studies and already applied to patients in a small pilot study, open possibilities for sharing experience across the world without travelling. Application of those technologies to neurovascular, and particularly stroke interventions, may be very timely in view of the need for expert neuro-interventionalists located mostly in central areas.

Blood residence time to assess significance of coronary artery stenosis

Coronary artery stenosis is a narrowing of coronary lumen space caused by an atherosclerotic lesion. Fractional flow reserve (FFR) is the gold standard metric to assess physiological significance of coronary stenosis, but requires an invasive procedure. Computational modeling in conjunction with patient-specific imaging demonstrates formation of regions of recirculatory flow distal to a stenosis, increasing mean blood residence time relative to uninhibited flow. A new computational parameter, mean blood residence time (BloodRT), was computed for 100 coronary artery segments for which FFR was known. A threshold for BloodRT was determined to assess the physiological significance of a stenosis, analogous to diagnostic threshold for FFR. Model sensitivity and specificity of BloodRT for diagnosis of hemodynamically significant coronary stenosis was 98% and 96% respectively, compared with FFR. When applied to clinical practice, this could potentially allow practicing cardiologists to accurately assess the severity of coronary stenosis without resorting to invasive techniques.

Diagnostic performance of intracoronary optical coherence tomography-based versus angiography-based fractional flow reserve for the evaluation of coronary lesions.

The aim of this study was to evaluate the diagnostic performance of OCT-based optical flow ratio (OFR) in unselected patients and compare it with angiography-based quantitative flow ratio (QFR), using wire-based FFR as reference standard. All patients with OCT and FFR assessment prior to revascularisation were analysed. OFR and QFR were computed in a blinded fashion and compared with FFR, applying the same cut-off value of ≤0.80 to all to define ischaemia. Paired comparison between OFR and QFR was performed in 212 vessels from 181 patients. Average FFR was 0.82±0.10 and 40.1% of vessels had an FFR ≤0.80. OFR showed a significantly better correlation and agreement with FFR than QFR (r=0.87 versus 0.77, p<0.001; SD of the difference=0.05 versus 0.07, p<0.001). The AUC was 0.97 for OFR, higher than for QFR (difference=0.05, p=0.017), and much higher than the minimal lumen area (difference=0.15, p<0.001) and diameter stenosis (difference=0.17, p<0.001). Diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio for OFR to identify FFR ≤0.80 were 92%, 86%, 95%, 92%, 91%, 18.2 and 0.2, respectively. The diagnostic accuracy of OFR was not significantly different in MI-related vessels (95% versus 90%, p=0.456), or in vessels with and without previously implanted stents (90% versus 93%, p=0.669). OFR had an excellent agreement with FFR in consecutive patients with coronary artery disease. OFR was superior to QFR, and much better than conventional morphological parameters in determining physiological significance of coronary stenosis. The diagnostic performance of OFR was not influenced by the presence of prior myocardial infarction or implanted stents.

Accuracy of 3-dimensional and 2-dimensional quantitative coronary angiography for predicting physiological significance of coronary stenosis: a FAVOR II substudy.

Three-dimensional quantitative coronary angiography (3D-QCA) enables reconstruction of a coronary artery in 3D from two angiographic image projections. This study compared the diagnostic accuracy of 3D-QCA vs. 2-dimensional (2D) QCA in predicting physiologically significant coronary stenosis, using fractional flow reserve (FFR) as the reference standard. All interrogated vessels in the FAVOR II China study and the FAVOR II Europe-Japan study were assessed by 2D-QCA and 3D-QCA according to standard operating procedures in core laboratories. QCA analysts were blinded to the corresponding FFR values. A total of 645 vessels from 576 patients with 3D-QCA, 2D-QCA, and FFR were analyzed. Using the conventional cut-off value of 50% for percent diameter stenosis (DS%), 3D-QCA was more accurate in predicting FFR ≤0.80 than 2D-QCA [accuracy 74.0% (95% CI: 69.9-77.7%) vs. 64.9% (95% CI: 61.3-68.7%), difference: 9.1%, P<0.001]. Sensitivity was higher by 3D-QCA compared with 2D-QCA [69.1% (95% CI: 63.0-75.1%) vs. 47.1% (95% CI: 40.5-53.6%), difference: 22.0%, P<0.001] and specificity was similar [76.5% (95% CI: 72.5-80.6%) vs. 74.4% (95% CI: 70.2-78.6%), difference: 2.1%, P=0.40]. Area under the receiver operating characteristic curve was significantly higher for 3D-QCA than for 2D-QCA [0.81 (95% CI: 0.77-0.84) vs. 0.66 (95% CI: 0.62-0.71), P<0.001]. 3D-QCA demonstrated better diagnostic performance in predicting physiologically significant coronary stenosis compared with 2D-QCA, when FFR was used as the reference standard.

TCT-617 Diagnostic Accuracy of 3-Dimensional and 2-Dimensional Quantitative Coronary Angiography for Predicting Physiological Significance of Coronary Stenosis

Three-dimensional (3D) quantitative coronary angiography (QCA) provides a more accurate depiction of the true vessel geometry by construction of the coronary artery in 3D. The aim of this study was to compare the diagnostic accuracy of 3D-QCA with 2D-QCA in determining the functional significance of

Fractional flow reserve (FFR) et instantaneous wave-free ratio (iFR), l’évaluation physiologique d’une sténose coronarienne dans le laboratoire de catéthérisme cardiaque : mise au point et guide pratique

In recent years, a large body of evidence has revealed the limitations of angiographic evaluation in determining the physiological significance of coronary stenosis, particularly when these are intermediate lesions. Percutaneous coronary interventions (PCI) guided by physiological assessment using fractional flow reserve (FFR) have been shown to reduce cardiovascular events when compared to angiography alone. Recently, another coronary physiologic parameter has been introduced: the “instantaneous wave-free ratio” (iFR). In this review, we will discuss the FFR, the iFR, and their use in the functional assessment of coronary stenosis in the cardiac catheterization laboratory. This review will cover theoretical aspects for non-interventional cardiologists, as well as practice points and common pitfalls related to coronary physiological assessment for interventional cardiologists.

Intravascular Ultrasound and Fractional Flow Reserve in Assessment of the Intermediate Coronary Stenosis

Fractional flow reserve (FFR) may be regarded as a gold standard for the evaluation of the physiological significance of coronary stenosis in the catheterization laboratory with extensive validation in randomized, controlled trials ([1][1]). The beauty of FFR lies in its consistent ischemic

The role of myocardial perfusion imaging in special populations: Women, diabetics, and heart failure

Cardiovascular disease and its manifestations remain a major worldwide public health problem. Despite significant advances in diagnosis and treatment, coronary artery disease remains the leading cause of death of men and women in the developed world. Early and accurate diagnosis of coronary artery disease is crucial if men and women are to have improved outcomes. The continuous and dramatic growth in the field of nuclear cardiology during the past 2 decades has accounted for its central role in the clinical evaluation of patients with known or suspected coronary heart disease. The development of electrocardiogram-gated single photon emission tomography has facilitated the expansion of nuclear cardiology studies from the evaluation of myocardial perfusion alone to the evaluation of both perfusion and ventricular function data in a single study. Myocardial perfusion imaging with electrocardiogram-gated single photon emission tomography, with its ability to provide information about the physiologic significance of coronary stenosis, left ventricular function, and risk assessment of patients with coronary artery disease, is ideally suited for the diagnostic and prognostic evaluation of the patient who is at high to intermediate risk for ischemic heart disease.

Nuclear cardiology and electron-beam computed tomography: competitive or complementary?

Electron-beam computed tomography (EBCT) and nuclear cardiology techniques are both valuable in the noninvasive assessment of patients with suspected coronary artery disease. The techniques, however, are different in the information they provide about the patient. EBCT provides anatomic information on coronary atherosclerosis, whereas myocardial perfusion single-photon emission computed tomography assesses the physiologic significance of coronary stenosis. Because of these differences, the techniques are highly complementary. In considering the complementary nature of these methods, it is important to clarify the issues being raised. An important question in the consideration of a patient with known or suspected coronary artery disease is, What is the risk in an individual patient of developing clinical coronary artery disease? The answer to this question will determine who needs aggressive medical management. A second question in a suspected coronary artery disease patient is, What is the risk of cardiac death? As will be discussed, this risk, in general, determines the need to consider coronary revascularization. In the former question, EBCT testing and clinical assessment alone is usually sufficient, and in some cases nuclear testing can be of additional value. In answering the second question, on the basis of currently available data, the EBCT and nuclear cardiology studies appear to be operating in a complementary fashion.

Validation of Doppler FloWire for measurement of coronary flow reserve in humans.

Previous studies have validated the 133Xenon (133Xe) method to assess regional myocardial blood flow and coronary flow reserve (CFR). Doppler FloWire (DFW) has been used recently for measuring CFR to assess the physiological significance of coronary stenosis. Data obtained by DFW has never been correlated to 133Xe. Our study compared data from DFW measurement of CFR to that obtained by 133Xe in 31 consecutive patients with variable coronary stenosis. Regional myocardial blood flow was measured by assessing the rate constants of 133Xe washout using multicrystal gamma camera after injection (20 millicuries) in the right or left coronary artery. CFR was assessed by measuring resting and hyperemic coronary blood flow by 133Xe and DFW using i.v. adenosine (140 mcg/k/min x 3 min). CFR was also measured by DFW giving intracoronary (i.c.) adenosine (12 microg in the right coronary, 18 microg in the left). In both methods--133Xe and DFW--coronary flow reserve was defined as the ratio of maximal hyperemic-to-baseline flow. DFW and 133Xe assessment of CFR correlated highly, whether adenosine was used i.c.(r=0.87; P=0.0001) or i.v.(r=0.78; P=0.0001). CFR obtained by DFW following i.c. and i.v. adenosine correlated well (r=0.79; P=0.0001). i.c. adenosine has fewer side effects. Both DFW and 133Xe are comparable in measuring CFR in humans.

Slope of the instantaneous hyperemic diastolic coronary flow velocity-pressure relation. A new index for assessment of the physiological significance of coronary stenosis in humans.

Coronary flow reserve (CFR), the functional index of stenosis severity more frequently used in the catheterization laboratory, is greatly affected by the hemodynamic conditions at the time of measurement and cannot be applied in the immediate assessment of the outcome of coronary interventions. The aim of the present study was to establish the feasibility and reproducibility of the assessment of the slope of the instantaneous diastolic relation between coronary flow velocity and aortic pressure during maximal hyperemia (IHDVPS) using a spectral analysis of the intracoronary Doppler signal, to assess the sensitivity and specificity of this index in the detection of flow-limiting coronary stenoses in comparison with CFR, and to study the possibility of determining the zero-flow pressure from the intercept of the velocity-pressure relation on the pressure axis during a controlled cardiac arrest. The instantaneous peak coronary flow velocity measured after intracoronary papaverine with a Doppler guidewire was plotted against the simultaneously measured aortic pressure, and the slope of the velocity-pressure relation in the phase of progressive diastolic velocity decrease was calculated during four consecutive beats. In nine normal arteries, a controlled diastolic cardiac arrest was induced by an intracoronary bolus injection of 3 mg adenosine. The IHDVPS could be assessed in 79 of 95 patients (83%), with a moderate intraobserver variability (0.4 +/- 11% after independent selection of different beats during maximal hyperemia). The IHDVPS showed no significant correlation with heart rate, mean diastolic aortic pressure, type of vessel studied, and cross-sectional area at the site of the velocity recording. The IHDVPS was significantly lower in arteries with > or = 30% diameter stenosis than in normal or near-normal arteries (0.71 +/- 0.48 versus 1.73 +/- 0.80 cm.s-1.mm Hg-1, P < .0000002). In the stenosis group, both IHDVPS and CFR were significantly correlated with the minimal luminal cross-sectional area (r = .46, P < .05 and r = .62, P < .002, respectively). The study of the velocity-pressure relation during long diastolic pauses showed a curvilinear relation between velocity and pressure in the lower pressure range, with an upward concavity to the velocity axis and no intercept with the pressure axis in most cases. The IHDVPS can distinguish between arteries with and without coronary stenoses and has a significant inverse correlation with the severity of the stenosis. Under the stable hemodynamic conditions of this study, the IHDVPS and CFR had similar sensitivities and specificities in distinguishing normal and stenotic vessels and demonstrated similar correlation with minimal luminal cross-sectional area. The curvilinearity of the velocity-pressure relation during long diastolic pauses, possibly due to a significant reduction of luminal cross-sectional area at low pressures, complicates the use of the flow velocity-pressure relation for the assessment of the zero-flow pressure.

Positron emission tomography as a diagnostic tool. A reassessment based on literature review.

Currently used clinical diagnostic imaging modalities, such as magnetic resonance imaging (MRI) and x-ray computed tomography (CT) provide predominantly anatomic information. CT images reflect x-ray attenuation distribution in the body, whereas MRI signals depend primarily on proton density and tissue relaxivity. In contrast to these predominantly anatomic modalities, positron emission tomography (PET) reflects tissue physiology and metabolism. Although PET has been used predominantly as a research tool, the clinical use of this technique for the detection, noninvasive characterization, and treatment planning of selected disease processes has been extensively studied in oncology, cardiology, and neurology. The author examined currently available literature to reassess the potential role of PET as a diagnostic tool in the following specific clinical situations: (1) the differentiation of radiation necrosis from tumor recurrence; (2) the characterization of the physiologic significance of coronary stenosis and the evaluation of the myocardial viability; and (3) the localization of the epileptogenic foci.

Intraoperative assessment of the physiologic significance of coronary stenosis in humans

Coronary angiography is generally considered the gold standard in assessing the significance of coronary stenosis. The inadequacy of coronary angiography has frequently been demonstrated by intraoperative findings that differ from those projected by the catheterization report. To better assess the physiologic significance of coronary stenosis, we measured intramyocardial pH intraoperatively in 50 myocardial segments supplied by stenotic coronary arteries before and after revascularization in 42 patients undergoing coronary artery bypass grafting. The hemodynamic, electrocardiographic, and pH responses to atrial pacing were recorded intraoperatively before and after revascularization. The coronary angiograms, performed within 3 months before bypass grafting, were reviewed by a single independent observer. Preoperative and postoperative radionuclide ventriculograms were performed and also reviewed by an independent observer. In response to atrial pacing, a fall exceeding 0.02 pH units was considered to represent ischemia and was observed in 28 segments. Patients exhibiting this response comprised Group I. Twenty-two segments demonstrated a fall of less than 0.02 pH units or a rise in pH in response to atrial pacing. Patients having this response comprised Group II. Segments in Group I responded dramatically to revascularization, with the pH during atrial pacing rising from -0.09 +/- 0.01 to -0.02 +/- 0.01 (p less than 0.001). Nine patients demonstrated ischemic S-T changes during atrial pacing, all in Group I. Pre-pacing hemodynamic parameters were similar in both groups. Group I patients, however, demonstrated a significant fall in mean arterial pressure during atrial pacing, from 92.0 +/- 3.0 to 78.4 +/- 3.3 mm Hg (p less than 0.001) whereas Group II patients did not. Twelve segments that angiograms indicated were supplied by critically stenotic vessels (greater than 75%) failed to demonstrate a significant fall in their pH during atrial pacing. In these segments, intraoperative findings and postoperative results corroborated the metabolic findings. Coronary angiography, therefore, was only 45% specific in assessing physiologically significant obstructions. The degree of segmental wall motion abnormalities likewise correlated poorly with the pH changes. Unlike coronary angiography, the response of intramyocardial pH to pacing is an accurate metabolic tool to assess myocardial ischemia in humans.