Intracoronary pressures to predict myocardial viability in patients with ischemic left ventricular dysfunction.

To investigate the role of intracoronary pressure parameters in the assessment of viability in the myocardium subtending a significant coronary stenosis. In patients with ischemic left ventricular dysfunction, the presence of myocardial viability is related to the expected benefits derived from coronary revascularization. Intracoronary pressure wire-based measurements were performed in 64 coronary lesions of ≥50% stenosis severity of 59 patients with postischemic left ventricular dysfunction, segmental left ventricular wall motion abnormalities, and substantial viability in the myocardial territory subtending the investigated stenotic coronaries, defined as the percent summed rest score in the target territory (%SRStarget ) ≤60% at the single-photon emission tomography. Invasive pressure-derived indexes like resting and hyperemic Pd/Pa, ΔPd/Pa, and %ΔPd/Pa (defined as the absolute difference and percent decrease between resting and hyperemic Pd/Pa respectively) were compared with %SRStarget . A significant correlation was found between ΔPd/Pa (Spearman's p: -0.760, p < 0.001) and %ΔPd/Pa (p: -0.733; p < 0.001) with %SRStarget. These results were confirmed after correction for potential confounders. According to %SRStarget median value, myocardial areas with high and low viability were compared: ΔPd/Pa and %ΔPd/Pa were significantly higher in areas with high viability (p < 0.001 for both). According to receiver operating characteristic curves, we identified two cut-offs (ΔPd/Pa > 0.11 and %ΔPd/Pa > 15%) able to predict >80% viability with good sensitivity and specificity. Our study suggests that, in patients with postischemic left ventricular dysfunction and significant coronary stenosis, intracoronary pressures indexes like ΔPd/Pa and %ΔPd/Pa are able to predict the magnitude of downstream myocardial viability.

Development, validation, and reproducibility of the pullback pressure gradient (PPG) derived from manual fractional flow reserve pullbacks.

Fractional flow reserve (FFR) pullbacks assess the location and magnitude of pressure drops along the coronary artery. The pullback pressure gradient (PPG) quantifies the FFR pullback curve and provides a numeric expression of focal versus diffuse coronary artery disease. This study aims (1) to validate the PPG using manual FFR pullbacks compared with motorized FFR pullbacks as a reference; and (2) to determine the intra- and interoperator reproducibility of the PPG derived from manual FFR pullbacks. Patients with stable coronary artery disease and an FFR ≤ 0.80 were included. All patients underwent FFR pullback evaluation either with a motorized device or manually, depending on the study cohort. The agreement of the PPG between repeated pullbacks was assessed using the Bland-Altman method. Overall, 116 FFR pullback maneuvers (96 manual and 20 motorized) were analyzed. There was excellent agreement between the PPG derived from manual and motorized pullbacks (mean difference -0.01 ± 0.07, 95% limits of agreement [LOA] -0.14 to 0.12). The intra- and interoperator reproducibility of PPG derived from manual pullbacks were excellent (mean difference <0.01, 95% LOA -0.11 to 0.12, and mean difference <0.01, 95% LOA -0.12 to 0.11, respectively). The duration of the pullback maneuver did not impact the reproducibility of the PPG (r = 0.12, 95% CI: -0.29 to 0.49, p = 0.567). Manual pullbacks allow for an accurate PPG calculation. The inter- and intraoperator reproducibility of PPG derived from manual pullbacks were excellent.

A quick glance at selected topics in this issue.

"A quick glance at selected topics in this issue" aims to highlight contents of the Journal and provide a quick review to the readers.

A quick glance at selected topics in this issue.

"A quick glance at selected topics in this issue" aims to highlight contents of the Journal and provide a quick review to the readers.

Coronary circulation: Pressure/flow parameters for assessment of ischemic heart disease.

Both invasive and non-invasive parameters have been reported for assessment of the physiological status of the coronary circulation. Fractional flow reserve and coronary (or myocardial) flow reserve may be obtained by invasive or non-invasive means. These metrics of coronary stenosis severity have achieved wide clinical acceptance for guiding revascularization decisions and risk stratification. Other indices are obtained invasively (e.g., instantaneous wave-free ratio, iFR; hyperemic stenosis resistance) or non-invasively (e.g., PET absolute myocardial blood flow (mL/min/g)) and have been used for the same purposes. Both iFR, and whole-cycle distal coronary to aortic mean pressure (Pd/Pa) are measured under basal condition and used for assessment of hemodynamic stenosis severity as is index of basal stenosis resistance (BSR). These metrics typically are dichotomized at an empirically derived cut point into "normal" and "abnormal" categories for purposes of clinical decision making and data analysis. Once dichotomized the indices do not always point in the same direction and so confusion may arise. This review, therefore, will present basic principles relevant to understanding commonly employed metrics of the physiological status of the coronary circulation, potential strengths and weaknesses, and hopefully an improved appreciation of the clinical information provided by each.

Functional evaluation of intracranial atherosclerotic stenosis by pressure ratio measurements.

Background: Fractional flow reserve is widely used for the functional evaluation of coronary artery stenosis. Some studies have similarly used the translesional pressure ratio measurements for the functional evaluation of intracranial atherosclerotic stenosis. In this paper, we aimed to investigate the relationship between pressure ratio and cerebral tissue perfusion by MR perfusion imaging and provided a non-invasive method for evaluating the functional significance of intracranial atherosclerotic stenosis. Methods: A total of 18 consecutive patients with intracranial atherosclerotic stenosis patients including 19 stenotic vessels were recruited. The pressure was measured using a pressure guidewire, the pressure ratio before and after the endovascular intervention was calculated and compared with the severity of diameter stenosis and perfusion-derived MR (the time to maximum tissure residue function (Tmax)). Moreover, the DSA-derived pressure ratio was computed using a novel computational fluid dynamics-based model, termed CFD-PR, and was compared with the actual pressure ratio to assess its diagnostic accuracy. Results: The pressure ratio increased after percutaneous transluminal angioplasty or stenting, while the correlation between pressure ratio and diameter stenosis was not significant. The pressure ratio was negatively correlated with Tmax (r = -0.73, P < 0.01), and a 95% confidence interval for the cutoff value of pressure ratio = 0.67 (95% confidence interval: 0.58-0.76) was suggested. There was a good correlation (mean = 0.02, Spearman's correlation coefficient r = 0.908, P < 0.001) and agreement (limits of agreement: -0.157 to 0.196, P = 0.954) between CFD-PR and the actual pressure ratio. Conclusions: This exploratory study indicates the pressure ratio may correlate with the perfusion status. The pressure ratio can be calculated through a non-invasive method using a computational fluid dynamics-based method.

Advances in Diagnosis, Therapy, and Prognosis of Coronary Artery Disease Powered by Deep Learning Algorithms.

Percutaneous coronary intervention has been a standard treatment strategy for patients with coronary artery disease with continuous ebullient progress in technology and techniques. The application of artificial intelligence and deep learning in particular is currently boosting the development of interventional solutions, improving the efficiency and objectivity of diagnosis and treatment. The ever-growing amount of data and computing power together with cutting-edge algorithms pave the way for the integration of deep learning into clinical practice, which has revolutionized the interventional workflow in imaging processing, interpretation, and navigation. This review discusses the development of deep learning algorithms and their corresponding evaluation metrics together with their clinical applications. Advanced deep learning algorithms create new opportunities for precise diagnosis and tailored treatment with a high degree of automation, reduced radiation, and enhanced risk stratification. Generalization, interpretability, and regulatory issues are remaining challenges that need to be addressed through joint efforts from multidisciplinary community.

Symptomatic Myocardial Bridging in D-Transposition of the Great Arteries Post-Arterial Switch.

We present Stanford's experience with patients post-arterial switch operation presenting with chest pain found to have hemodynamically significant myocardial bridging. The evaluation of symptomatic patients post-arterial switch should not only include assessment for coronary ostial patency but also for nonobstructive coronary conditions such as myocardial bridging. (Level of Difficulty: Advanced.).

Diagnostic and Therapeutic Strategies for Stable Coronary Artery Disease Following the ISCHEMIA Trial.

Until recently, coronary revascularization with coronary artery bypass grafting or percutaneous coronary intervention has been regarded as the standard choice for stable coronary artery disease (CAD), particularly for patients with a significant burden of ischemia. However, in conjunction with remarkable advances in adjunctive medical therapy and a deeper understanding of its long-term prognosis from recent large-scale clinical trials, including ISCHEMIA (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches), the approach to stable CAD has changed drastically. Although the updated evidence from recent randomized clinical trials will likely modify the recommendations for future clinical practice guidelines, there are still unresolved and unmet issues in Asia, where prevalence and practice patterns are markedly different from those in Western countries. Herein, the authors discuss perspectives on: 1) assessing the diagnostic probability of patients with stable CAD; 2) application of noninvasive imaging tests; 3) initiation and titration of medical therapy; and 4) evolution of revascularization procedures in the modern era.

A novel transit-time flow metric, diastolic resistance index, detects subcritical anastomotic stenosis in coronary artery bypass grafting.

Objective: Transit time flow measurement (TTFM) can detect critical anastomotic stenosis during coronary artery bypass grafting. However, the identification of subcritical stenosis remains challenging. We hypothesized that diastolic resistance index (DRI), a novel TTFM metric, is more effective in evaluating subcritical stenosis than the currently available TTFM metrics. DRI is used to measure changes in the diastolic versus systolic resistance of distal anastomosis. Methods: A total of 123 coronary bypass anastomoses in 35 patients were prospectively analyzed. During coronary artery bypass grafting, the mean graft flow (Qmean), pulsatility index, and diastolic filling were obtained. DRI was calculated using the intraoperative recordings of TTFM and arterial pressure. Postoperatively, stenosis of anastomoses was categorized into successful (<50%), subcritical (50%-74%), and critical (≥75%) via multidetector computed tomography scan. Results: In total, 93 (76%), 13 (10%), and 17 (14%) anastomoses were graded as successful, subcritical, and critical, respectively. DRI and diastolic filling could distinguish subcritical from successful anastomoses (P < .01 and < .01, respectively), whereas Qmean and pulsatility index could not (P = .12 and .39, respectively). The receiver operating characteristic curves were established to evaluate the diagnostic ability for detecting ≥50% stenosis. In left anterior descending artery grafting (n = 55), DRI had the highest area under the curve (0.91), followed by diastolic filling (0.87), Qmean (0.74), and pulsatility index (0.65). Conclusions: DRI and diastolic filling had a reliable diagnostic ability for detecting ≥50% stenosis during coronary artery bypass grafting. In left anterior descending artery grafting, DRI had a more satisfactory detection capability than other TTFM metrics.

Transcatheter Occlusion of Coronary-Pulmonary Fistula With a Liquid Embolic Agent After Evaluation by FFR.

A 58-year-old man was admitted for stable angina. The coronary angiogram revealed a coronary-pulmonary fistula with a nonsignificant atheroma. We decided to perform percutaneous embolization of the fistula in view of the symptoms and the hemodynamic assessment findings. Embolization was performed using a liquid embolic agent with no residual flow. (Level of Difficulty: Intermediate.).

Differences in Plaque Characteristics and Myocardial Mass: Implications for Physiological Significance.

Background: The mechanism of the fractional flow reserve (FFR) difference according to sex has not been clearly understood. Objectives: This study sought to evaluate sex differences in coronary stenosis, plaque characteristics, and left ventricular (LV) mass and their implications for physiological significance. Methods: This was a post hoc analysis of a pooled population of multicenter, international prospective cohorts. Patients (166 women and 489 men) underwent coronary computed tomography angiography (CCTA) within 90 days before invasive FFR measurements were included. The minimal lumen area, percent of plaque burden, whole vessel plaque volume by composition, high-risk plaque characteristics, and LV mass were analyzed from CCTA images. Results: Among 1,188 vessels analyzed, the FFR value was higher in women than that in men (0.85 ± 0.13 vs 0.82 ± 0.14; P = 0.001) despite a similar percentage of diameter stenosis between the sexes (45.9% ± 18.9% vs 46.1% ± 17.7%; P = 0.920). The composition of fibrofatty plaque + necrotic core (13.1% ± 16.9% vs 21.2% ± 19.9%; P < 0.001) and frequencies of low attenuation plaque (12.7% vs 24.5%; P < 0.001) and positive remodeling (33.8% vs 45.5%; P = 0.001) were lower in women than in men. Vessel, plaque, and lumen volumes were significantly smaller in women than that in men (all P < 0.001); however, no sex difference was observed in any of these parameters after adjustment for LV mass (all P > 0.10). Sex was not an independent predictor of the FFR value after adjustment for stenosis severity, plaque characteristics, and LV mass. Conclusions: Higher FFR values for the same stenosis severity in women can be explained by fewer high-risk plaque characteristics and smaller myocardial mass in women than that in men. (CCTA-FFR Registry for Risk Prediction; NCT04037163).

Prognosis and Medical Cost of Measuring Fractional Flow Reserve in Percutaneous Coronary Intervention.

Background: There are limited data regarding comparative prognosis and medical cost between fractional flow reserve (FFR)-based and angiography-based percutaneous coronary intervention (PCI) among revascularized patients. Objectives: This study evaluates prognosis and medical cost of FFR use in revascularized patients by PCI. Methods: Using the National Health Insurance Service database, stable or unstable angina patients who underwent PCI from 2011 to 2017 were evaluated. Eligible patients were divided into 2 groups according to use of FFR in PCI. Primary outcome was a composite of all-cause death or spontaneous myocardial infarction (MI). Secondary outcomes included individual components of the primary outcome, unplanned revascularization, and medical costs. Results: Among 134,613 eligible patients, PCI was performed based on angiography (n = 129,497) and FFR (n = 5,116). During the study period, both the annual number and proportion of use of FFR in PCI increased (all P for trend <0.001). The FFR group showed significantly lower risk of the primary outcome (7.0% vs 9.5%; P < 0.001), all-cause death (5.8% vs 7.7%; P = 0.001), and spontaneous MI (1.6% vs 2.2%; P = 0.022) than the angiography group. Although the FFR group showed higher medical cost during index admission than angiography group (median: $6,265.10 vs $5,385.60; P < 0.001), cumulative medical cost after index admission was significantly lower ($2,696.50 vs. $3,142.10; P < 0.001). Conclusions: Use of FFR in PCI in stable or unstable angina patients showed significantly lower risk of all-cause death and spontaneous MI compared to angiography-based PCI. Although the FFR group had higher initial medical cost than the angiography group, cumulative medical cost after index admission was significantly lower.

Patient-specific fluid-structure simulations of anomalous aortic origin of right coronary arteries.

Objectives: Anomalous aortic origin of the right coronary artery (AAORCA) may cause ischemia and sudden death. However, the specific anatomic indications for surgery are unclear, so dobutamine-stress instantaneous wave-free ratio (iFR) is increasingly used. Meanwhile, advances in fluid-structure interaction (FSI) modeling can simulate the pulsatile hemodynamics and tissue deformation. We sought to evaluate the feasibility of simulating the resting and dobutamine-stress iFR in AAORCA using patient-specific FSI models and to visualize the mechanism of ischemia within the intramural geometry and associated lumen narrowing. Methods: We developed 6 patient-specific FSI models of AAORCA using SimVascular software. Three-dimensional geometries were segmented from coronary computed tomography angiography. Vascular outlets were coupled to lumped-parameter networks that included dynamic compression of the coronary microvasculature and were tuned to each patient's vitals and cardiac output. Results: All cases were interarterial, and 5 of 6 had an intramural course. Measured iFRs ranged from 0.95 to 0.98 at rest and 0.80 to 0.95 under dobutamine stress. After we tuned the distal coronary resistances to achieve a stress flow rate triple that at rest, the simulations adequately matched the measured iFRs (r = 0.85, root-mean-square error = 0.04). The intramural lumen remained narrowed with simulated stress and resulted in lower iFRs without needing external compression from the pulmonary root. Conclusions: Patient-specific FSI modeling of AAORCA is a promising, noninvasive method to assess the iFR reduction caused by intramural geometries and inform surgical intervention. However, the models' sensitivity to distal coronary resistance suggests that quantitative stress-perfusion imaging may augment virtual and invasive iFR studies.

Coronary CT FFR vs Invasive Adenosine and Dobutamine FFR in a Right Anomalous Coronary Artery.

We present the management of an anomalous coronary artery originating from the opposite sinus of Valsalva with comprehensive diagnostic workup including noninvasive coronary computed tomography (CT) derived fractional flow reserve (FFR) and invasive dobutamine-volume challenge-FFR/intravascular ultrasound. After surgical operation, treatment success was quantified by anatomical and functional analysis in postoperative CT. (Level of Difficulty: Advanced.).

Correlation between quantification of myocardial area at risk and ischemic burden at cardiac computed tomography.

Purpose: This study aims to investigate the correlation between myocardial area at risk at coronary computed tomography angiography (CCTA) and the ischemic burden derived from myocardial computed tomography perfusion (CTP) by using the 17-segment model. Methods: Forty-two patients with chest pain complaints who underwent a combined CCTA and CTP protocol were identified. Patients with reversible ischemia at CTP and at least one stenosis of ≥ 50% at CCTA were selected. Myocardial area at risk was calculated using a Voronoi-based segmentation algorithm at CCTA and was defined as the sum of all territories related to a ≥ 50% stenosis as a percentage of the total left ventricular (LV) mass. The latter was calculated using LV contours which were automatically drawn using a machine learning algorithm. Subsequently, the ischemic burden was defined as the number of segments demonstrating relative hypoperfusion as a percentage of the total amount of segments (=17). Finally, correlations were tested between the myocardial area at risk and the ischemic burden using Pearson's correlation coefficient. Results: A total of 77 coronary lesions were assessed. Average myocardial area at risk and ischemic burden for all lesions was 59% and 23%, respectively. Correlations for ≥ 50% and ≥ 70% stenosis based myocardial area at risk compared to ischemic burden were moderate (r = 0.564; p < 0.01) and good (r = 0.708; p < 0.01), respectively. Conclusion: The relation between myocardial area at risk as calculated by using a Voronoi-based algorithm at CCTA and ischemic burden as assessed by CTP is dependent on stenosis severity.

Percutaneous Coronary Intervention for Left Main Coronary Artery Disease: Present Status and Future Perspectives.

For several decades, coronary artery bypass grafting has been regarded as the standard choice of revascularization for significant left main coronary artery (LMCA) disease. However, in conjunction with remarkable advancement of device technology and adjunctive pharmacology, percutaneous coronary intervention (PCI) offers a more expeditious approach with rapid recovery and is a safe and effective alternative in appropriately selected patients with LMCA disease. Several landmark randomized clinical trials showed that PCI with drug-eluting stents for LMCA disease is a safe option with similar long-term survival rates to coronary artery bypass grafting surgery, especially in those with low and intermediate anatomic risk. Although it is expected that the updated evidence from recent randomized clinical trials will determine the next guidelines for the foreseeable future, there are still unresolved and unmet issues of LMCA revascularization and PCI strategy. This paper provides a comprehensive review on the evolution and an update on the management of LMCA disease.

Outcomes after coronary angiography for unstable angina compared to stable angina, myocardial infarction and an asymptomatic general population.

Background: The outcomes of real-world unstable angina (UA) in the high-sensitivity troponin era are unclear. We aimed to investigate the outcomes of UA referred to coronary angiography compared to stable angina (SA), non-ST-segment elevation myocardial infarction (NSTEMI), STEMI and a general population. Methods: We included the 9,694 patients with no prior coronary artery disease (CAD) referred to invasive or CT coronary angiography from 2013 to 2018 in Northern Norway (51% SA, 12% UA, 23% NSTEMI and 14% STEMI), and 11,959 asymptomatic individuals recruited from the Tromsø Study. We used Cox models to estimate the hazard ratios (HR) for all-cause mortality and major adverse cardiovascular events (MACE), defined as cardiovascular death, MI or obstructive CAD. Results: The median follow-up time was 2.8 years. The incidence rate of death was 8.5 per 1000 person-years (95 % confidence interval [CI] 8.0-9.0) in the general population, 9.7 (95 % CI 8.3-11.5) in SA, 14.9 (95 % CI 11.4-19.6) in UA, 29.7 (95 % CI 25.6-34.3) in NSTEMI and 36.5 (95 % CI 30.9-43.2) in STEMI. In multivariable adjusted analyses, compared with UA, SA had a 38 % lower risk of death and a non-significant lower risk of MACE (HR 0.62, 95 % CI 0.44-0.89; HR 0.86, 95 % CI 0.66-1.11). NSTEMI had a 2.4-fold higher risk of death (HR 2.39, 95 % CI 1.38-4.14) and a 1.6-fold higher risk of MACE (HR 1.62, 95 % CI 1.11-2.38) compared tox UA during the first year after coronary angiography, but a similar risk thereafter. There was no difference in the risk of death for UA with non-obstructive CAD and obstructive CAD (HR 0.78, 95 % CI 0.39-1.57). Conclusion: UA had a higher risk of death but a similar risk of MACE compared to SA and a lower 1-year risk of death and MACE compared to NSTEMI.

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

Background: Artificial intelligence enables simultaneous evaluation of plaque morphology and computational physiology from optical coherence tomography (OCT). Objectives: This study sought to appraise the predictive value of major adverse cardiovascular events (MACE) by combined plaque morphology and computational physiology. Methods: 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. Results: 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). Conclusions: 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.

Immediate impact of coronary artery bypass graft surgery on regional myocardial perfusion: Results from the Collaborative Pilot Study to Determine the Correlation Between Intraoperative Observations Using Spy Near-Infrared Imaging and Cardiac Catheterization Laboratory Physiological Assessment of Lesion Severity.

Objectives: Coronary artery bypass grafting (CABG) is performed using anatomic guidance. Data connecting the physiologic significance of the coronary vessel stenosis to the acute physiologic response to grafting are lacking. The Collaborative Pilot Study to Determine the Correlation Between Intraoperative Observations Using Spy Near-Infrared Imaging and Cardiac Catheterization Laboratory Physiological Assessment of Lesion Severity study is the first to compare preintervention coronary physiology with the acute regional myocardial perfusion change (RMP-QC) at CABG in a per-graft analysis. Methods: Non-emergent patients undergoing diagnostic catheterization suitable for multivessel CABG were enrolled. Synergy between Percutaneous Coronary Intervention with Taxus score, fractional flow reserve (FFR), instantaneous wave free ratio (iFR), and quantitative coronary angiography was documented in 75 epicardial coronary arteries, with 62 angiographically intermediate and 13 severe stenoses. At CABG, near-infrared fluorescence analysis quantified the relative change (post- vs pregrafting, termed RMP-QC) in the grafted vessel's perfusion territory. Scatter plots were constructed for RMP-QC versus quantitative coronary angiography and RMP-QC versus FFR/iFR. Exact quadrant randomization test for randomness was used. Results: There was no relationship between RMP-QC and quantitative coronary angiography percent diameter stenosis, whether all study vessels were included (P = .949) or vessels with core-lab quantitative coronary angiography only (P = .922). A significant nonrandom association between RMP-QC and FFR (P = .025), as well as between RMP-QC and iFR (P = .008), was documented. These associations remained when excluding vessels with assigned FFR and iFR values (P = .0092 and P = .0006 for FFR and iFR, respectively). Conclusions: The Collaborative Pilot Study to Determine the Correlation Between Intraoperative Observations Using Spy Near-Infrared Imaging and Cardiac Catheterization Laboratory Physiological Assessment of Lesion Severity study demonstrates there is no association between angiographic coronary stenosis severity and the acute perfusion change after grafting; there is an association between functional stenosis severity and absolute increase in regional myocardial perfusion after CABG.