Physiological Significance Of Coronary Lesions Research Articles

Validation of angiography-derived Murray law-based quantitative flow reserve (μQFR) against pressure-derived instantaneous wave-free ratio for assessing coronary lesions, a single-center study in Egypt

BackgroundInstantaneous wave-free ratio (iwFR) is a well-validated method for functional evaluation of intermediate coronary lesions. A recently developed Murray law-based QFR (µQFR) allows wire-free FFR estimation using a high-quality single angiographic projection. We aim to determine the diagnostic accuracy of µQFR as compared to wire-based iwFR for physiological assessment of coronary lesions in a sample of Egyptian patients.ResultsOver a one-year period, patients who previously underwent iwFR assessment of an intermediate coronary stenosis (40–90%) were retrospectively included. μQFR analysis was then performed offline using a dedicated artificial intelligence (AI)-aided computation software. All the measurements were performed blinded to iwFR results, and the agreement between iwFR and μQFR values was tested. Forty-nine patients (mean age 57.9 ± 9 years, 72.9% males) were included. Mean value of iwFR and μQFR was 0.90 ± 0.075 and 0.79 ± 0.129, respectively. There was a significant moderate positive linear correlation between μQFR and iwFR (r = 0.47, p = 0.001; 95% CI 0.22–0.68) with moderate-to-substantial agreement between the two methods (Kappa 0.6). In assessing the diagnostic accuracy of μQFR, the receiver operating characteristic (ROC) curve yielded an area under the curve (AUC) of 0.84 (95% CI 0.717–0.962) for predicting functionally significant lesions defined as iwFR < 0.89. The sensitivity and specificity of μQFR < 0.8 for detecting physiological significance of coronary lesions were 89% and 74% with positive and negative predictive values of 70 and 91%, respectively.ConclusionµQFR has good diagnostic accuracy for predicting functionally significant coronary lesions with moderate correlation and agreement with the gold standard iwFR. Angiography-derived µQFR could be a promising tool for improving the utilization of physiology-guided revascularization.

Diagnostic performance of virtual fractional flow reserve derived from routine coronary angiography using segmentation free reduced order (1-dimensional) flow modelling

Fractional flow reserve (FFR) improves assessment of the physiological significance of coronary lesions compared with conventional angiography. However, it is an invasive investigation. We tested the performance of a virtual FFR (1D-vFFR) using routine angiographic images and a rapidly performed reduced order computational model. Quantitative coronary angiography (QCA) was performed in 102 with coronary lesions assessed by invasive FFR. A 1D-vFFR for each lesion was created using reduced order (one-dimensional) computational flow modelling derived from conventional angiographic images and patient specific estimates of coronary flow. The diagnostic accuracy of 1D-vFFR and QCA derived stenosis was compared against the gold standard of invasive FFR using area under the receiver operator characteristic curve (AUC). QCA revealed the mean coronary stenosis diameter was 44% ± 12% and lesion length 13 ± 7 mm. Following angiography calculation of the 1DvFFR took less than one minute. Coronary stenosis (QCA) had a significant but weak correlation with FFR (r = -0.2, p = 0.04) and poor diagnostic performance to identify lesions with FFR <0.80 (AUC 0.39, p = 0.09), (sensitivity - 58% and specificity - 26% at a QCA stenosis of 50%). In contrast, 1D-vFFR had a better correlation with FFR (r = 0.32, p = 0.01) and significantly better diagnostic performance (AUC 0.67, p = 0.007), (sensitivity - 92% and specificity - 29% at a 1D-vFFR of 0.7). 1D-vFFR improves the determination of functionally significant coronary lesions compared with conventional angiography without requiring a pressure-wire or hyperaemia induction. It is fast enough to influence immediate clinical decision-making but requires further clinical evaluation.

Physiology-Guided Management of Serial/Diffuse Coronary Artery Disease.

Just over four decades ago, the management of coronary artery disease (CAD) witnessed a major breakthrough with the advent of minimally invasive treatment modalities like angioplasty followed by coronary stenting. Dr. Andreas Gruentzig pioneered this field in 1977 by adding a balloon to the Dotter catheter. From its inception, he was cognizant of the need for measuring pressures before and after balloon inflation in the treated coronary artery, device placement in the treated coronary artery. However, for decades subsequently, emphasis was placed primarily on preprocedural non-invasive tests and angiographic assessment of lesions based on percent diameter stenosis to guide therapeutic interventions. We review the progress of these physiologic advancements in management over the last 20years, as well as the current state and prospects for the future. More recently, clinical features heavily drive the decision whether or not to stent the diseased segment. A little more than two decades ago, a new approach to facilitate the decision whether or not to intervene on intermediate stenoses began to evolve. It became clear that other features besides angiography are important when considering benefit of mechanical intervention. The emphasis shifted to assessment of the physiological significance of coronary lesions, rather than solely anatomical identification of lesions at angiography. Physiological assessments have served to better discriminate potentially flow-limiting lesions, utilizing cutoff measurements to determine which patients would benefit from intervention in addition to medical therapy. We have found that there is still need for arrival at a consensus as regards the best practice in the context of physiological assessment of serial stenotic lesions, but that studies do show that techniques currently available are non-inferior to each other, and highly effective.

TCT-531 INTRACORONARY VS. INTRAVENOUS ADENOSINE FOR FRACTIONAL FLOW RESERVE MEASUREMENT: A META-ANALYSIS

Intravenous (IV) infusion of adenosine represents the gold standard for measuring Fractional Flow Reserve (FFR) in order to assess physiological significance of coronary lesions. However, IV adenosine preferably requires a central venous catheter and is more expensive and time-consuming as compared

Current developments and future applications of intracoronary hemodynamics.

Intracoronary hemodynamic assessment of the physiologic significance of coronary lesions improves clinical outcomes in patients with coronary artery disease. Coronary flow velocity reserve, fractional flow reserve, instantaneous wave-free ratio, and index of microcirculatory resistance utilize sensor-mounted guidewires to approximate coronary flow. Coronary flow velocity reserve and fractional flow reserve rely on pharmacologic administration of adenosine to achieve hyperemia and diagnose epicardial lesion severity. As an adenosine-free index, the instantaneous wave-free ratio utilizes a wave-free period in the mid-late diastole during which resistance is constant and low to assess lesion significance. The index of microcirculatory resistance combines hyperemic pressure measurements with thermodilution to quantify microvascular resistance. We review the physiology, clinical trials, and clinical applications of these invasive hemodynamic assessments.

Circulation : Cardiovascular Imaging

<i>Circulation</i> : <i>Cardiovascular Imaging</i>

Cardiac myocardial perfusion imaging using dual source computed tomography

The ability to simultaneously visualize both coronary atherosclerosis and myocardial perfusion may enable the assessment of the anatomical burden and physiological significance of coronary lesions in a single exam. In this paper we introduce a novel use of the dual source CT: pharmacologically induced stress myocardial perfusion imaging, (SP-DSCT). We describe an experimental protocol by which we used the DSCT to assess both stress and rest myocardial perfusion in order to identify areas of infarcted and ischemic myocardium. Based on our initial investigations, this protocol is feasible and can be used to identify hemodynamically significant stenosis. Nevertheless, further studies are required to determine the incremental value of this technique to traditional coronary CT angiography and/or nuclear stress myocardial perfusion imaging.

TU‐C‐342‐03: Physiological Assessment of Coronary Artery Disease Based On Angiographic Image Data

Coronary arteriography is the standard method for determination of coronary anatomy and assessment of atherosclerosis. However, there are definite limitations to the use of visual estimation to assess the severity of coronary artery disease and luminal stenosis. These limitations include the large intraobserver and interobserver variability that result from subjective visual grading of coronary stenotic lesions. This is especially true in the case of an intermediate coronary lesion (30%–70% diameter stenosis), where coronary arteriography is very limited in distinguishing ischemia‐producing intermediate coronary lesions from non‐ischemia‐producing ones. Furthermore, pathologic findings have shown a lack of correlation between the severity of coronary stenosis as estimated from coronary arteriogram and the actual severity of stenotic lesions measured in postmortem hearts. Because of the major limitations of standard coronary arteriography, a method for functional measure of stenosis severity such as measurement of fractional flow reserve obtainable during cardiac catheterization is desirable. The fractional flow reserve measurement would provide valuable functional information in addition to the anatomical data obtained during routine coronary arteriography.Fractional flow reserve was introduced to provide a physiological measure of coronary stenosis by quantifying the reduction in maximum coronary blood flow from a theoretical maximum normal flow in the presence of a lesion. Currently, fractional flow reserve is approximated by dividing the pressure distal to the stenosis by the aortic pressure. The distal pressure is measured using a pressure‐sensing wire that has passed across the stenosis, and the aortic pressure is measured simultaneously at the catheter tip with a pressure transducer. Pressure‐based fractional flow reserve has proven to aid the evaluation of the flow‐limiting potential of stenoses as well as the therapeutic gain of angioplasties. However, an alternative technique that can measure fractional flow reserve using only angiographic images would be a valuable tool in the cardiac catheterization laboratory because the acquired images used for visual assessment of stenosis severity can also be used to quantify physiological alterations imposed by the stenosis. In other words, fractional flow reserve could potentially be measured using only image data without the need to pass a pressure wire across a stenosis. The blood flow through the stenotic lesion is measured with a first pass distribution analysis technique and the theoretical normal blood flow is estimated by using a measurable parameter that correlates well with it. Scaling law relationships indicate that the total coronary arterial volume can be used as a surrogate measure of normal blood flow. The details of the methodology for fractional flow reserve quantification using angiographic image data will be discussed.This lecture will provide an overview of the emerging techniques for assessment of the physiological significance of coronary lesions measured in the cardiac catheterization laboratory.Educational Objectives:1. Understand the current techniques available for measurement of fractional flow reserve in the cardiac catheterization laboratory.2. Understand the methodology for coronary blood flow measurement using angiographic image data.3. Understand the methodology for fractional flow reserve measurement using angiographic image data.

Integrated Single-Photon Emission Computed Tomography and Computed Tomography Coronary Angiography for the Assessment of Hemodynamically Significant Coronary Artery Lesions

The purpose of this study was to assess the physiologic significance of coronary artery lesions with an integrated single-photon emission computed tomography (SPECT) and computed tomography coronary angiography (CTCA) device. Myocardial perfusion imaging (MPI) with SPECT is of value for assessing the physiologic significance of coronary lesions. Computed tomography coronary angiography is a new technique to noninvasively detect coronary stenosis, with high sensitivity and negative predictive value (NPV) but lower specificity and positive predictive value (PPV). The experimental SPECT/CTCA hybrid imaging device (Infinia gamma camera and LightSpeed16 CT, General Electric, Milwaukee, Wisconsin) enables concurrent assessment of coronary anatomy and myocardial perfusion. Fifty-six patients with angina pectoris underwent single-session SPECT-MPI and CTCA with the hybrid device and coronary angiography (CA) within 4 weeks. The ability of fused SPECT/CTCA images to diagnose physiologically significant lesions showing >50% stenosis and reversible perfusion defects in the same territory was determined and compared with CTCA stand-alone. Of a total of 224 coronary segments in 56 patients, 12 patients and 54 segments (23%) were excluded from further analysis of CTCA. Overall, 170 coronary segments were evaluated. The sensitivity, specificity, PPV, and NPV of CTCA were 96%, 63%, 31%, and 99%, respectively, as compared with 96%, 95%, 77%, and 99%, respectively, for SPECT/CTCA. Hybrid SPECT/CTCA imaging results in improved specificity and PPV to detect hemodynamically significant coronary lesions in patients with chest pain. Single-photon emission computed tomography/CTCA might play a potentially important role in the noninvasive diagnosis of coronary artery disease and introduce an objective decision-making tool for assessing the need for interventions in each occluded vessel.

Correlations between coronary flow reserve measured with a Doppler guide wire and treadmill exercise testing

We compared exercise test results to a physiologic depiction of stenosis severity, coronary flow reserve (CFR), measured with a Doppler guide wire in 35 patients with single-vessel coronary disease. Group 1 ( n = 21) had abnormal CFR, and group 2 ( n = 14) had normal CFR. In group 1, 14 of 21 had ST-segment depression versus 3 of 14 in group 2 ( p < 0.01). Exercise treadmill time (Bruce protocol) was normalized to the age- and sex-predicted time. Exercise time and normalized exercise time were less in group 1 (5.6 ± 2.3 vs 9.9 ± 1.8 min and 0.82 ± 0.32 vs 1.25 ± 0.23, p < 0.00001). Having either ST-segment depression or a normalized exercise time <1 during exercise had a 95% sensitivity, 71% specificity, and 86% predictive accuracy in identifying abnormal CFR. Coronary stenoses and minimal lumen diameter were similar in groups 1 and 2. By using stepwise logistical regression analysis, exercise time and ST-segment depression predicted CFR with a total r 2 of 0.51. Minimal lumen diameter did not significantly add to the model. Exercise test variables, ST-segment depression, and exercise time are predictive of the physiologic significance of coronary lesions. (Am Heart J 1997;134:99-104.)

Relation among stenosis severity, myocardial blood flow, and flow reserve in patients with coronary artery disease.

Coronary arteriography is considered the "gold standard" for evaluating the severity of a coronary stenosis. Because the resistance to blood flow through a stenotic lesion depends on a number of lesion characteristics, the physiological significance of coronary lesions of intermediate severity is often difficult to determine from angiography alone. This study of patients with coronary artery disease seeks to determine the relation between myocardial blood flow and flow reserve measured by positron emission tomography (PET) and the percent area stenosis on quantitative coronary arteriography. We studied 28 subjects: 18 patients with coronary artery disease (66 +/- 8 years) and 10 age-matched healthy volunteers (64 +/- 13 years) with dynamic N-13 ammonia PET imaging at rest and after dipyridamole (0.56 mg/kg). The percent cross-sectional area stenosis was quantified on the coronary arteriograms as described by Brown et al. In the 18 patients, a total of 41 non-infarct-related coronary vessels were analyzed. Myocardial blood flows in normal regions of patients with coronary artery disease were not different than those in healthy volunteers, both at rest and after dipyridamole. As a result, the myocardial flow reserve was also similar in both groups (2.4 +/- 0.4 versus 2.6 +/- 0.7, respectively; P = NS). Quantitative PET estimates of hyperemic blood flow (r = .81, P < .00001), flow reserve (r = .78, P < .00001), and an index of the "minimal coronary resistance" (r = .78, P < .00001) were inversely and nonlinearly correlated with the percent area stenosis on angiography. Of note, PET estimates of myocardial flow reserve successfully differentiated coronary lesions of intermediate severity (50% to 70% and 70% to 90%; 2.4 +/- 0.4 versus 1.8 +/- 0.5, respectively; P = .04). In patients with coronary artery disease, non-invasive measurements of myocardial blood flow and flow reserve by PET are inversely and nonlinearly related to stenosis severity as defined by quantitative angiography. Importantly, coronary lesions of intermediate severity have a differential flow reserve that decreases as stenosis increases that can be detected noninvasively by PET, thus allowing better definition of the functional importance of known coronary stenosis.

Effect of increases in heart rate and arterial pressure on coronary flow reserve in humans

Objectives. The objective of this study was to determine the effect of increases in heart rate and arterial pressure on maximal pharmacologic coronary Wood flow reserve.Background. Coronary flow reserve measurements are useful in assessment of the physiologic significance of coronary lesions. However, animal studies suggest that alterations in hemodynamic status may influence coronary flow reserve independent of coronary stenosis.Methods. Coronary flow reserve was measured during cardiac catheterization with the use of a 3F coronary Doppler catheter and intracoronary papaverine. Flow reserve was measured under control conditions and during increases in heart rate produced by atrial pacing (18 patients) or during elevation of arterial pressure by intravenous phenylephrine infusion (9 patients) with intracoronary alpha-adrenergic blockade by phentolamine.Results. Coronary flow reserve progressively decreased from 3.7 ± 0.9 (mean ± SD) at the rate of 71 ± 8 beats/min at rest to 3.0 ± 0.6 during pacing at 100 beats/min and to 2.6 ± 0.5 during pacing at 120 beats/min. Flow reserve decreased because of a progressive increase in rest coronary flow velocity during pacing (122 +- 16% of control value at 100 beats/min, 139 ± 16% of control value at 120 beats/min), whereas papaverine hyperemia peak velocity remained unchanged. Flow reserve decreased with pacing tachycardia whether the initial flow reserve was normal or depressed. Mean arterial pressure increased from 95 ± 12 mm Hg to 130 ± 8 mm Hg daring intravenous phenylephrine infusion and to 123 ± 10 mm Hg during combined intravenous phenylephrine and intracoronary phentolamine infusions. Coronary flow reserve was not affected by the blood pressure increases control value 4.3 ± 1.0, phenytephrine 4.4 ± 1.5, phenylephrine and phentolamine 4.4 ± 2.0).Conclusions. Sudden increases in heart rate but not mean arterial pressure lead to a substantial reduction in maximal coronary blood flow reserve. These data suggest that the diagnostic utility of all flow reserve measurement techniques might be improved by standardization of heart rate during measurement or extrapolation of the measured flow reserve to that expected at a reference heart rate.

Assessing the physiologic significance of coronary obstructions in patients: Importance of diffuse undetected atherosclerosis

T HE HALLMARK OF coronary atherosclerosis is an apparently localized obstruction of a conduit coronary vessel. Until Sones introduced the technique of selective coronary angiography,’ for the most part the anatomy of these localized coronary obstructions could only be defined at postmortem. The ability to anatomically define coronary obstructions with a broadly applicable clinical technique has vastly altered our approach to the diagnosis and treatment of coronary atherosclerosis. Each new step forward, however, immediately brings forth new questions. Thus, coronary angiography has forced physicians to develop approaches of defining the physiologic significance of coronary lesions that can be demonstrated angiographically. Accurately assessing the physiologic significance of coronary obstructive lesions is critical to clinical decision making. The need for coronary bypass surgery, percutaneous transluminal coronary angioplasty, the adequacy of prior bypass surgery and percutaneous transluminal coronary angioplasty, and the validation of noninvasive approaches to the diagnosis of coronary disease all critically depend on assessing the physiological significance of coronary obstructive lesions. For more than two decades, the physiological significance of coronary obstructions detected by coronary angiography has been assessed primarily by visual estimates of percent stenosis. To a lesser extent clinicians have used other aspects of the patients’ clinical presentation including symptoms and results of various noninvasive procedures. Because percent stenosis remains the gold standard today in more than 99% of hospitals that perform coronary angiography, this review will examine the advantages and disadvantages of this approach.

Coronary Obstructive Lesions: Assessing Their Physiological Significance in Humans

For more than two decades cardiologists and cardiac surgeons have estimated the physiologic significance of coronary lesions by measuring percent stenosis of the obstructive vascular segment from coronary angiograms. Such measurements, when performed without computer-based analysis, are associated with substantial variability between observers, as well as within a single observer. In addition, recent intraoperative measurements of coronary reserve in individual obstructed vessels of patients with multivessel coronary disease performed with a suction Doppler probe indicate that, in the intermediate range (10% to 90% diameter stenosis), percent stenosis measurements of coronary lesions by angiography correlates poorly with coronary reserve. These studies suggest that the physiologic significance of coronary obstructions cannot be accurately assessed by visual interpretation of coronary angiograms. More sophisticated and accurate approaches are needed for assessing the physiologic significance of coronary obstructions preoperatively.