Prediction of progression of coronary artery disease and clinical outcomes using vascular profiling of endothelial shear stress and arterial plaque characteristics: the PREDICTION Study

Defining "Vulnerable" in coronary artery disease: predisposing factors and preventive measures

The likelihood of a plaque to cause an acute coronary syndrome (ACS) depends on several factors, both lesion- and patient-related. One of the most investigated and established contributing factors is the presence of high-risk or "vulnerable plaque" characteristics, which have been correlated with increased incidence of major adverse cardiovascular events (MACE). The recognition, however, that a significant percentage of vulnerable plaques do not result in causing clinical events has led the scientific community towards the more multifaceted concept of "vulnerable patients". Incorporating the morphological features of an atherosclerotic plaque into its hemodynamic surroundings can better predict the chance of its disruption, as altered fluid dynamics play a significant role in plaque destabilization. The advances in coronary imaging and the field of computational fluid dynamics (CFD) can contribute to develop more accurate lesion- and patient-related ACS prediction models that take into account both the morphology of a plaque and the forces applied upon it. The aim of this review is to provide the latest data regarding the aforementioned predictive factors as well as relevant preventive measures.

Reliability of characterising coronary artery flow with the flow-split outflow strategy: Comparison against the multiscale approach

BACKGROUND

In computational modelling of coronary haemodynamics, imposing patient-specific flow conditions is paramount, yet often impractical due to resource and time constraints, limiting the ability to perform a large number of simulations particularly for diseased cases.

OBJECTIVE

To compare coronary haemodynamics quantified using a simplified flow-split strategy with varying exponents against the clinically verified but computationally intensive multiscale simulations under both resting and hyperaemic conditions in arteries with varying degrees of stenosis.

METHODS

Six patient-specific left coronary artery trees were segmented and reconstructed, including three with severe (>70 %) and three with mild (<50 %) focal stenoses. Simulations were performed for the entire coronary tree to account for the flow-limiting effects from epicardial artery stenoses. Both a 0D-3D coupled multiscale model and a flow-split approach with four different exponents (2.0, 2.27, 2.33, and 3.0) were used. The resulting prominent haemodynamic metrics were statistically compared between the two methods.

RESULTS

Flow-split and multiscale simulations did not significantly differ under resting conditions regardless of the stenosis severity. However, under hyperaemic conditions, the flow-split method significantly overestimated the time-averaged wall shear stress by up to 16.8 Pa (p = 0.031) and underestimate the fractional flow reserve by 0.327 (p = 0.043), with larger discrepancies observed in severe stenoses than in mild ones. Varying the exponent from 2.0 to 3.0 within the flow-split methods did not significantly affect the haemodynamic results (p > 0.141).

CONCLUSIONS

Flow-split strategies with exponents between 2.0 and 3.0 are appropriate for modelling stenosed coronaries under resting conditions. Multiscale simulations are recommended for accurate modelling of hyperaemic conditions, especially in severely stenosed arteries.(247/250 words).

Low endothelial shear stress is associated with increased coronary atherosclerotic plaque activity in patients that presented with acute coronary syndrome

BACKGROUND

Both coronary atherosclerotic plaque activity and low endothelial shear stress (ESS) are predictive of adverse cardiovascular events. We aimed to investigate their association and relationship with high-risk plaque features.

METHODS

Coronary computed tomography angiography (CCTA) based flow simulations were used to compute ESS in patients presenting with acute coronary syndrome proceeding percutaneous coronary intervention. Associations between ESS, CCTA plaque features and coronary plaque activity, measured by 18F-sodium fluoride (18F-NaF) positron emission tomography (PET), were investigated at the coronary segment and vessel level.

RESULTS

ESS and coronary plaque activity were both analyzed in 330 coronary segments and 123 vessels. The area of low ESS (<0.4 ​Pa), termed low shear area (LSA), was larger in 18F-NaF positive regions increasing from median 11.7 ​mm2 (IQR: 4.6-27.4) to 29.0 ​mm2 (IQR: 14.1-55.2) at the segment level (P ​< ​0.0001) and from median 27.3 ​mm2 (IQR: 8.6-65.3) to 57.8 ​mm2 (26.6-108.2) at the vessel level (P ​= ​0.0049). The maximum tissue-to-background ratio of 18F-NaF activity positively correlated with LSA at the segment level (rs ​= ​0.27; P ​< ​0.0001) and at the vessel level (rs ​= ​0.38; P ​< ​0.0001). LSA was associated with spotty calcification at both the segment (P <0.0001) and vessel level (P ​= ​0.0042) and positive remodeling at the vessel level (P ​= ​0.025).

CONCLUSIONS

In patients with acute coronary syndrome, LSA is associated with increased coronary atherosclerotic plaque activity, as measured by 18F-NaF PET.

Could Right Coronary Artery-Aorta Angle be Used to Predict Atherosclerotic Lesion Localization in Critical Site of the Right Coronary Artery in Patients With Right Dominancy?

BACKGROUND

This study aimed to evaluate the impact of the aorta-right coronary artery angle (ARA) on lesion localization and its protective effect in the critical osteal region in patients with dominant right coronary artery (RCA).

METHODS

This cross-sectional study included 294 patients who underwent elective coronary angiography for stable angina pectoris and had a single significant lumen stenosis (50%-95%) before the RCA crux. Patients with tortuous vessels, previous interventions, left-dominant circulation, or insufficient image quality were excluded. ARA, lesion criticality, length, and distance from the aorto-osteal junction were calculated using quantitative coronary analysis. Patients were categorized based on lesion location: osteal, proximal, mid, and distal regions.

RESULTS

ARA increased significantly as the lesion localization moved distally (osteal: 53.26° ± 5.65°, proximal: 60.79° ± 9.53°, mid: 82.33° ± 9.85°, distal: 93.53° ± 7.46°; p < 0.0001). A strong positive correlation was found between ARA and the distance of the lesion from the aorto-osteal junction (r = 0.759, p < 0.0001). In binary regression, ARA was the only independent risk factor for critical lesion localization in the osteal region (OR = 0.915; 95% CI 0.868-0.965, p < 0.001). ROC analysis showed that an ARA > 73.50° had 83.2% sensitivity and 81.3% specificity for excluding critical lesions in the osteal region (AUC = 0.861; 95% CI 0.815-0.907).

CONCLUSION

A narrow ARA increases the likelihood of critical lesions in the osteal RCA, while an ARA > 73.50° is protective. These findings suggest ARA could guide risk assessment and treatment planning in coronary interventions.

Engineering advanced in vitro models of endothelial dysfunction

Endothelial dysfunction is an important initiator of cardiovascular disease, the leading cause of death globally, and often manifests in arterial regions with disturbed blood flow. Experimental model advances have crucially helped unravel physiological mechanisms. While in vivo models provide a dynamic environment, they often fail to mimic human physiology precisely and face significant ethical barriers. Advanced in vitro models, including organs-on-chips and bioreactors, combine human cells and blood flow to accurately replicate endothelial dysfunction. Newer models have enhanced scalability and accuracy, with organs-on-chips commonly outperforming standard preclinical methods. Importantly, recent endothelial dysfunction discoveries leverage dynamic models to identify and evaluate clinically promising therapeutics. Here, we examine these developments and explore opportunities to develop next-generation in vitro models of endothelial dysfunction.

Role of shear stress-induced red blood cell released ATP in atherosclerosis

Altered hemodynamics is a key factor for atherosclerosis. For decades, endothelial cell (EC) responses to fluid-generated wall shear stress have been the central focus for atherogenesis. However, circulating blood is not a cell-free fluid, it contains mechanosensitive red blood cells (RBCs) that are also subjected to altered hemodynamics and release a large amount of ATP, but their impact on atherosclerosis has been overlooked. The focus of this study is the role of shear stress (SS)-induced RBC-released ATP in atherosclerosis. Hypercholesterolemic mouse models with and without RBC-Pannexin 1 deletion were used for the study. Results showed that SS-induced release of ATP from RBCs was at µM concentrations, three-orders of magnitude higher than that from other cell types. Suppression of RBC-released ATP via deletion of Pannexin 1, a mechanosensitive ATP-permeable channel, reduced high-fat diet-induced aortic plaque burden by 40%-60%. Importantly, the location and the extent of aortic atherosclerotic lesions spatially matched with the ATP deposition profile at aortic wall predicted by a computational fluid dynamic (CFD) model. Furthermore, hypercholesterolemia increases EC susceptibility to ATP with potentiated increase in [Ca2+]i, an initial signaling for aortic EC barrier dysfunction, and an essential cause for lipid accumulation and inflammatory cell infiltration. The computational prediction also provides a physics-based explanation for RBC-released ATP-induced sex disparities in atherosclerosis. Our study reveals an important role of RBC-released ATP in the initiation and progression of atherosclerosis. These novel findings provide a more comprehensive view of how altered hemodynamics and systemic risk factors synergistically contribute to atherosclerosis.NEW & NOTEWORTHY This study reveals that, in addition to fluid-derived wall shear stress, the disturbed blood flow-induced release of ATP from mechanosensitive red blood cells (RBCs), the major cellular components of blood, along with hypercholesterolemia-induced increases in endothelial cell susceptibility to ATP contribute significantly to the initiation and progression of atherosclerosis. These novel findings advance our current understanding of how altered hemodynamics and hypercholesterolemia synergistically contribute to atherosclerosis for the first time with the inclusion of RBCs.

Vulnerable or High-Risk Plaque: A JACC: Cardiovascular Imaging Position Statement

The concept of high-risk plaque emerged from pathologic and epidemiologic studies 3 decades ago that demonstrated plaque rupture with thrombosis as the predominant mechanism of acute coronary syndrome and sudden cardiac death. Thin-cap fibroatheroma, a plaque with a large lipidic core covered by a thin fibrous cap, is the prototype of the rupture-prone plaque and has been traditionally defined as "vulnerable plaque." Although knowledge on the pathophysiology of plaque instability continues to grow, the risk profile of our patients has shifted and the character of atherosclerotic disease has evolved, partly because of widespread use of lipid-lowering therapies and other preventive measures. In vivo intracoronary imaging studies indicate that superficial erosion causes up to 40% of acute coronary syndromes. This changing landscape calls for broader perspective, expanding the concept of high-risk plaque to the precursors of all major substrates of coronary thrombosis beyond plaque rupture. Other factors to take into consideration include dynamic changes in plaque composition, the importance of plaque burden, inflammatory activation (both local and systemic), healing mechanisms, regional hemodynamic pattern, properties of the fluid phase of blood, and the amount of myocardium at risk subtended by a lesion. Rather than the traditional focus limited to the thin-cap fibroatheroma, the authors advocate a more comprehensive approach that considers both morphologic features and biological activity of plaques and blood. This position paper highlights the challenges to the usual concept of high-risk plaque, proposes a broader definition, and analyzes its key morphologic features, the technological progress of plaque imaging (particularly using intracoronary imaging techniques), advances in pharmacologic therapies for plaque regression and stabilization, and the feasibility and efficacy of focal interventional treatments including preemptive plaque sealing.

Can fast wall shear stress computation predict adverse cardiac events in patients with intermediate non-flow limiting stenoses?

BACKGROUND AND AIMS

Coronary angiography-derived wall shear stress (WSS) may enable identification of vulnerable plaques and patients. A new recently introduced software allows seamless three-dimensional quantitative coronary angiography (3D-QCA) reconstruction and WSS computation within a single user-friendly platform carrying promise for clinical applications. This study examines for the first time the efficacy of this software in detecting vulnerable lesions in patients with intermediate non-flow limiting stenoses.

METHODS

This multicentre retrospective study included patients who had coronary angiography showing at least one lesion with borderline negative fractional flow reserve (FFR: 0.81-0.85). In these lesions, 3D-QCA reconstruction and blood flow simulation were performed using the CAAS Workstation WSS prototype (Pie Medical Imaging, Maastricht, Netherlands). Time averaged and multidirectional WSS were extracted across the lesion at every 3 mm segments. The primary endpoint of the study was lesion-oriented clinical events (LOCE), defined as the composite of cardiac death, target lesion related myocardial infarction (MI) or clinically indicated target lesion revascularization.

RESULTS

352 patients (355 lesions) were included in the analysis. Over a median follow-up of 4.1 years, 57 LOCE were recorded. Lesions causing events had a larger area stenosis (AS) [59.4 (54.6-67.7)% vs 52.8 (43.8-60.1)%, p < 0.001], maximum time averaged WSS (TAWSS) [11.56 (8.25-13.64)Pa vs 7.73 (5.41-11.51)Pa, p < 0.001], mean TAWSS at the minimum lumen area (MLA) [9.30 (5.44-11.94)Pa vs 6.19 (3.96-9.00)Pa, p < 0.001] and maximum transverse WSS [0.30 (0.21-0.45)Pa vs 0.23 (0.17-0.32)Pa, p=0.002] than those remaining quiescent. In multivariable models, AS was the only independent predictor of LOCE. Kaplan-Meier curves demonstrated that lesions with elevated maximum TAWSS and AS had a higher rate of LOCE than those with low TAWSS and AS values (26 % vs 7 %, p < 0.001).

CONCLUSIONS

For non-flow limiting lesions with borderline negative FFR, fast WSS computation using a dedicated software is feasible and holds potential for cardiovascular risk stratification.

Sensitivity of coronary hemodynamics to vascular structure variations in health and disease

Local hemodynamics play an essential role in the initiation and progression of coronary artery disease. While vascular geometry alters local hemodynamics, the relationship between vascular structure and hemodynamics is poorly understood. Previous computational fluid dynamics (CFD) studies have explored how anatomy influences plaque-promoting hemodynamics. For example, areas exposed to low wall shear stress (ALWSS) can indicate regions of plaque growth. However, small sample sizes, idealized geometries, and simplified boundary conditions have limited their scope. We generated 230 synthetic models of left coronary arteries and simulated coronary hemodynamics with physiologically realistic boundary conditions. We measured the sensitivity of hemodynamic metrics to changes in bifurcation angles, positions, diameter ratios, tortuosity, and plaque topology. Our results suggest that the diameter ratio between left coronary branches plays a substantial role in generating adverse hemodynamic phenotypes and can amplify the effect of other geometric features such as bifurcation position and angle, and vessel tortuosity. Introducing mild plaque in the models did not change correlations between structure and hemodynamics. However, certain vascular structures can induce ALWSS at the trailing edge of the plaque. Our analysis demonstrates that coronary artery vascular structure can provide key insight into the hemodynamic environments conducive to plaque formation and growth.

Spatial patterns of high-risk biomechanical metrics in plaques with abnormal vs. normal physiological flow indices

BACKGROUND

Plaques associated with abnormally low physiological flow reserve indices are appropriate for percutaneous coronary intervention (PCI). However, recent trials demonstrate that PCI of ischemia-producing lesions does not reduce major adverse cardiac events (MACE). Low endothelial shear stress (ESS) or high ESS gradient (ESSG) are associated with MACE wherever they occur along the plaque. This study aims to determine the presence of high-risk ESS metrics in obstructive coronary plaques with high-risk (<0.80) vs. borderline-risk (0.80-0.89) vs. normal Instantaneous Wave-free Ratio (iFR) (>0.89).

METHODS

We included 50 coronary arteries (50 patients) with variable iFR values who underwent coronary angiography and optical coherence tomography (OCT), followed by 3D reconstruction and computational fluid dynamics calculations of ESS/ESSG. The cohort was divided into 3 groups: iFR < 0.80, iFR 0.80-0.89, and iFR > 0.89. Spatial distribution of ESS metrics was reported along the course of each plaque, and high-risk ESS metrics and their location were compared among the 3 iFR subgroups.

RESULTS

High-risk ESS features (Minimal ESS, Maximum ESSG) were similarly distributed along the course of the atherosclerotic plaque in the three iFR subgroups, both in absolute value and in location: Min ESS: 0.5 ± 0.3 vs. 0.4 ± 0.2 vs. 0.4 ± 0.2 Pa respectively (p = 0.60); Max ESSG any direction: 13.7 ± 9.4 vs. 10.4 ± 10.6 vs. 10.0 ± 7.8 Pa/mm respectively (p = 0.30). ESS metrics were spatially located up to ≥18 mm from the plaque minimal luminal area (MLA) in both directions.

CONCLUSION

High-risk ESS metrics are similarly observed in plaques with normal or abnormal iFR, both in absolute value and spatial location in reference to the MLA. Utilizing iFR to identify plaques likely to cause MACE would miss the majority of plaques mechanistically at high-risk to destabilize and cause future adverse cardiac events.

Increased incidence of adverse events in diabetes mellitus patients with combined multiple vulnerable plaque features: new insights from the COMBINE OCT-FFR trial

AIMS

To evaluate the individual as well as combined impact of optical coherence tomography-detected vulnerability features (OCT-VFs) in the prediction of major adverse cardiovascular events (MACEs) in non-ischaemic lesions in patients with diabetes mellitus (DM).

METHODS AND RESULTS

The COMBINE OCT-FFR (NCT02989740) was a prospective, double-blind, international, natural-history study that included patients with DM having ≥1 lesions with a fractional flow reserve > 0.80, undergoing systematic OCT assessment. Pre-specified OCT-VFs included thin-cap fibroatheroma (TCFA), reduced minimal lumen area (r-MLA), high plaque burden (h-PB), and complicated plaque (CP). The primary endpoint (MACE) was a composite of cardiac mortality, target vessel myocardial infarction, clinically driven target lesion revascularization, or hospitalization for unstable angina up to 5 years, analysed according to the presence of these OCT-VFs, both individually and in combination. TCFA, r-MLA, h-PB, and CP were identified in 98 (25.1%), 159 (40.8%), 56 (14.4%), and 116 (29.8%) patients, respectively. The primary endpoint rate increased progressively from 6.9% to 50.0% (HR = 10.10; 95% CI, 3.37-30.25, P < 0.001) in patients without OCT-VFs compared with those with concomitant h-PB, r-MLA, CP, and TCFA. Importantly, while TCFA, h-PB, r-MLA, and CP were individually associated with the primary endpoint, the presence of two or more OCT-VFs significantly increased the likelihood of adverse events at 5 years.

CONCLUSION

In patients with DM and non-ischaemic lesions, TCFA, h-PB, r-MLA, and CP were predictors of adverse events. However, the presence of two or more OCT-VFs significantly increased the likelihood of MACE at 5 years. Further studies are warranted to confirm these findings and their potential clinical implications in a randomized fashion.

Hemodynamic effects of bifurcation and stenosis geometry on carotid arteries with different degrees of stenosis

Objective.Carotid artery stenosis (CAS) is a key factor in pathological conditions, such as thrombosis, which is closely linked to hemodynamic parameters. Existing research often focuses on analyzing the influence of geometric characteristics at the stenosis site, making it difficult to predict the effects of overall vascular geometry on hemodynamic parameters. The objective of this study is to comprehensively examine the influence of geometric morphology at different degrees of CAS and at bifurcation sites on hemodynamic parameters.Approach.A three-dimensional model is established using computed tomography angiography images, and eight geometric parameters of each patient are measured by MIMICS. Then, computational fluid dynamics is utilized to investigate 60 patients with varying degrees of stenosis (10%-95%). Time and grid tests are conducted to optimize settings, and results are validated through comparison with reference calculations. Subsequently, correlation analysis using SPSS is performed to examine the relationship between the eight geometric parameters and four hemodynamic parameters. In MATLAB, prediction models for the four hemodynamic parameters are developed using back propagation neural networks (BPNN) and multiple linear regression.Main results.The BPNN model significantly outperforms the multiple linear regression model, reducing mean absolute error, mean squared error, and root mean squared error by 91.7%, 93.9%, and 75.5%, respectively, and increasingR2from 19.0% to 88.0%. This greatly improves fitting accuracy and reduces errors. This study elucidates the correlation and patterns of geometric parameters of vascular stenosis and bifurcation in evaluating hemodynamic parameters of CAS.Significance.This study opens up new avenues for improving the diagnosis, treatment, and clinical management strategies of CAS.

A Pseudo-Spectral Method for Wall Shear Stress Estimation from Doppler Ultrasound Imaging in Coronary Arteries

PURPOSE

The Wall Shear Stress (WSS) is the component tangential to the boundary of the normal stress tensor in an incompressible fluid, and it has been recognized as a quantity of primary importance in predicting possible adverse events in cardiovascular diseases, in general, and in coronary diseases, in particular. The quantification of the WSS in patient-specific settings can be achieved by performing a Computational Fluid Dynamics (CFD) analysis based on patient geometry, or it can be retrieved by a numerical approximation based on blood flow velocity data, e.g., ultrasound (US) Doppler measurements. This paper presents a novel method for WSS quantification from 2D vector Doppler measurements.

METHODS

Images were obtained through unfocused plane waves and transverse oscillation to acquire both in-plane velocity components. These velocity components were processed using pseudo-spectral differentiation techniques based on Fourier approximations of the derivatives to compute the WSS.

RESULTS

Our Pseudo-Spectral Method (PSM) is tested in two vessel phantoms, straight and stenotic, where a steady flow of 15 mL/min is applied. The method is successfully validated against CFD simulations and compared against current techniques based on the assumption of a parabolic velocity profile. The PSM accurately detected Wall Shear Stress (WSS) variations in geometries differing from straight cylinders, and is less sensitive to measurement noise. In particular, when using synthetic data (noise free, e.g., generated by CFD) on cylindrical geometries, the Poiseuille-based methods and PSM have comparable accuracy; on the contrary, when using the data retrieved from US measures, the average error of the WSS obtained with the PSM turned out to be 3 to 9 times smaller than that obtained by state-of-the-art methods.

CONCLUSION

The pseudo-spectral approach allows controlling the approximation errors in the presence of noisy data. This gives a more accurate alternative to the present standard and a less computationally expensive choice compared to CFD, which also requires high-quality data to reconstruct the vessel geometry.

Software for optimized virtual stenting of patient-specific coronary arteries reconstructed from angiography images

Detection of clinically relevant stenosis within coronary arteries as well as planning of treatment (stent implantation) are important topics in clinical cardiology. In this study a thorough methodology for virtual stenting assistance is proposed, that includes the 3D reconstruction of a patient-specific coronary artery from X-ray angiography images, hemodynamic simulations of blood flow, computation of a fractional flow reserve (FFR) equivalent, virtual stenting procedure and an optimization of the virtual stenting, by considering not only the value of computed FFR, but also the low and high WSS regions and the state of arterial wall after stenting. The evaluation of the proposed methodology is performed in two ways: the calculated values of FFR are compared with clinically measured values; and the results obtained for automated optimized virtual stenting are compared with virtual stenting performed manually by an expert clinician for the whole considered dataset. The agreement of the results in almost all cases demonstrates the accuracy of the proposed approach, and the small discrepancies only show the capabilities and benefits this approach can offer. The automated optimized virtual stenting technique can provide information about the most optimal stent position that ensures the maximum achievable FFR, while also considering the distribution of WSS and the state of arterial wall. The proposed methodology and developed software can therefore be used as a noninvasive method for planning of optimal patient-specific treatment strategies before invasive procedures and thus help to improve the clinical outcome of interventions and provide better treatment planning adapted to the particular patient.

Coronary angiography: a review of the state of the art and the evolution of angiography in cardio therapeutics

Traditionally, coronary angiography was restricted to visual estimation of contrast-filled lumen in coronary obstructive diseases. Over the previous decades, considerable development has been made in quantitatively analyzing coronary angiography, significantly improving its accuracy and reproducibility.  Notably, the integration of artificial intelligence (AI) and machine learning into quantitative coronary angiography (QCA) holds promise for further enhancing diagnostic accuracy and predictive capabilities. In addition, non-invasive fractional flow reserve (FFR) indices, including computed tomography-FFR, have emerged as valuable tools, offering precise physiological assessment of coronary artery disease without the need for invasive procedures. These innovations allow for a more comprehensive evaluation of disease severity and aid in guiding revascularization decisions. This review traces the development of QCA technologies over the years, highlighting key milestones and current advancements. It also explores prospects that could revolutionize the field, such as AI integration and improved imaging techniques. By addressing both historical context and future directions, the article underscores the ongoing evolution of QCA and its critical role in the accurate assessment and management of coronary artery diseases. Through continuous innovation, QCA is poised to remain at the forefront of cardiovascular diagnostics, offering clinicians invaluable tools for improving patient care.

Endothelial Shear Stress Metrics Associate With Proinflammatory Pathways at the Culprit Site of Coronary Erosion

Low endothelial shear stress (ESS) and associated adverse biomechanical features stimulate inflammation, contribute to atherogenesis, and predispose to coronary plaque disruption. The mechanistic links between adverse flow-related hemodynamics and inflammatory mediators implicated in plaque erosion, however, remain little explored. We investigated the relationship of high-risk ESS metrics to culprit lesion proinflammatory/proatherogenic cells and cytokines/chemokines implicated in coronary plaque erosion in patients with acute coronary syndromes. In eroded plaques, low ESS, high ESS gradient, and steepness of plaque topographical slope associated with increased numbers of local T cells and subsets (CD4+, CD8+, natural killer T cells) as well as inflammatory mediators (interleukin [IL]-6, macrophage inflammatory protein-1β, IL-1β, IL-2).

Shear stress is uncoupled from atheroprotective KLK10 in atherosclerotic plaques

BACKGROUND AND AIMS

Physiological shear stress promotes vascular homeostasis by inducing protective molecules in endothelial cells (EC). However, physiological shear stress has been linked to atherosclerosis progression in some individuals with heightened cardiovascular risk. To address this apparent paradox, we hypothesized that diseased arteries may exhibit reduced responsiveness to the protective effects of physiological shear stress. Consequently, we compared the transcriptome of EC exposed to physiological shear stress in healthy arteries versus atherosclerotic conditions.

METHODS

Employing 3D light sheet imaging and computational fluid dynamics, we identified NOS3 as a marker of physiological shear stress in both healthy and atherosclerotic murine arteries. Single-cell RNA sequencing was performed on EC from healthy (C57BL/6) mice, mildly diseased (Apoe-/- normal diet) mice, and highly diseased (Apoe-/- high fat diet) mice. The transcriptomes of Nos3high cells (exposed to physiological shear stress) were compared among the groups.

RESULTS

Nos3high EC were associated with several markers of physiological shear stress in healthy arteries. Clustering of Nos3high EC revealed 8 different EC subsets that varied in proportion between healthy and diseased arteries. Cluster-specific nested functional enrichment of gene ontology terms revealed that Nos3high EC in diseased arteries were enriched for inflammatory and apoptotic gene expression. These alterations were accompanied by changes in several mechanoreceptors, including the atheroprotective factor KLK10, which was enriched in Nos3high EC in healthy arteries but markedly reduced in severely diseased arteries.

CONCLUSIONS

Physiological shear stress is uncoupled from atheroprotective KLK10 within atherosclerotic plaques. This sheds light on the complex interplay between shear stress, endothelial function, and the progression of atherosclerosis in individuals at risk of cardiovascular complications.

Comprehensive Risk Assessment of LAD Disease Progression in CCTA: The CLAP Score Study

BACKGROUND

a wider left main bifurcation angle (LMBA) has been linked to severe plaque development in the proximal left anterior descending artery (LAD). This study aimed to identify predictors of severe proximal LAD stenosis and major adverse cardiovascular events (MACE) using coronary computed tomography angiography (CCTA).

METHODS

from an initial cohort of 650 consecutive patients, we analyzed 499 patients who met the inclusion criteria after exclusions. Plaque morphology and characteristics were assessed by CCTA, and MACE occurrences were recorded at follow-up. A predictive score for LAD disease progression (CLAP score) was developed and validated.

RESULTS

severe proximal LAD stenosis was detected in 32% (160/499) of patients by CCTA. MACE occurred in 12.5% of patients at follow-up. Significant predictors of MACE were LMBA > 80° (HR: 4.47; 95% CI: 3.80-6.70; p < 0.001), diabetes (HR: 2.94; 95% CI: 1.54-4.63; p = 0.031), chronic kidney disease (HR: 1.71; 95% CI: 1.31-6.72; p = 0.041), high-risk plaques (HR: 2.30; 95% CI: 1.45-3.64; p < 0.01), obstructive CAD (HR: 2.50; 95% CI: 1.50 to 4.10, p = 0.01), and calcium score (CAC) (HR: 1.05; 95% CI: 1.02-1.08, p = 0.004). The CLAP score demonstrated good discriminatory power in both the development (AUC 0.91; 95% CI: 0.86-0.96) and validation cohorts (AUC 0.85; 95% CI: 0.79-0.91); Conclusions: LMBA > 80°, diabetes, chronic kidney disease, obstructive CAD, CAC score >180 and high-risk plaques were significant predictors of MACE in CCTA patients. The CLAP score effectively predicted LAD disease progression, aiding in risk stratification and optimization of intervention strategies for suspected coronary artery disease.

Patient-Specific Numerical Simulations of Coronary Artery Hemodynamics and Biomechanics: A Pathway to Clinical Use

PURPOSE

Numerical models that simulate the behaviors of the coronary arteries have been greatly improved by the addition of fluid-structure interaction (FSI) methods. Although computationally demanding, FSI models account for the movement of the arterial wall and more adequately describe the biomechanical conditions at and within the arterial wall. This offers greater physiological relevance over Computational Fluid Dynamics (CFD) models, which assume the walls do not move or deform. Numerical simulations of patient-specific cases have been greatly bolstered by the use of imaging modalities such as Computed Tomography Angiography (CTA), Magnetic Resonance Imaging (MRI), Optical Coherence Tomography (OCT), and Intravascular Ultrasound (IVUS) to reconstruct accurate 2D and 3D representations of artery geometries. The goal of this study was to conduct a comprehensive review on CFD and FSI models on coronary arteries, and evaluate their translational potential.

METHODS

This paper reviewed recent work on patient-specific numerical simulations of coronary arteries that describe the biomechanical conditions associated with atherosclerosis using CFD and FSI models. Imaging modality for geometry collection and clinical applications were also discussed.

RESULTS

Numerical models using CFD and FSI approaches are commonly used to study biomechanics within the vasculature. At high temporal and spatial resolution (compared to most cardiac imaging modalities), these numerical models can generate large amount of biomechanics data.

CONCLUSIONS

Physiologically relevant FSI models can more accurately describe atherosclerosis pathogenesis, and help to translate biomechanical assessment to clinical evaluation.

Advances in the Computational Assessment of Disturbed Coronary Flow and Wall Shear Stress: A Contemporary Review

Coronary artery blood flow is influenced by various factors including vessel geometry, hemodynamic conditions, timing in the cardiac cycle, and rheological conditions. Multiple patterns of disturbed coronary flow may occur when blood flow separates from the laminar plane, associated with inefficient blood transit, and pathological processes modulated by the vascular endothelium in response to abnormal wall shear stress. Current simulation techniques, including computational fluid dynamics and fluid-structure interaction, can provide substantial detail on disturbed coronary flow and have advanced the contemporary understanding of the natural history of coronary disease. However, the clinical application of these techniques has been limited to hemodynamic assessment of coronary disease severity, with the potential to refine the assessment and management of coronary disease. Improved computational efficiency and large clinical trials are required to provide an incremental clinical benefit of these techniques beyond existing tools. This contemporary review is a clinically relevant overview of the disturbed coronary flow and its associated pathological consequences. The contemporary methods to assess disturbed flow are reviewed, including clinical applications of these techniques. Current limitations and future opportunities in the field are also discussed.

Predicting coronary artery occlusion risk from noninvasive images by combining CFD-FSI, cGAN and CNN

Wall Shear Stress (WSS) is one of the most important parameters used in cardiovascular fluid mechanics, and it provides a lot of information like the risk level caused by any vascular occlusion. Since WSS cannot be measured directly and other available relevant methods have issues like low resolution, uncertainty and high cost, this study proposes a novel method by combining computational fluid dynamics (CFD), fluid-structure interaction (FSI), conditional generative adversarial network (cGAN) and convolutional neural network (CNN) to predict coronary artery occlusion risk using only noninvasive images accurately and rapidly. First, a cGAN model called WSSGAN was developed to predict the WSS contours on the vessel wall by training and testing the model based on the calculated WSS contours using coupling CFD-FSI simulations. Then, an 11-layer CNN was used to classify the WSS contours into three grades of occlusions, i.e. low risk, medium risk and high risk. To verify the proposed method for predicting the coronary artery occlusion risk in a real case, the patient's Magnetic Resonance Imaging (MRI) images were converted into a 3D geometry for use in the WASSGAN model. Then, the predicted WSS contours by the WSSGAN were entered into the CNN model to classify the occlusion grade.

Emerging Hybrid Intracoronary Imaging Technologies and Their Applications in Clinical Practice and Research

Intravascular ultrasound and optical coherence tomography are used with increasing frequency for the care of coronary patients and in research studies. These imaging tools can identify culprit lesions in acute coronary syndromes, assess coronary stenosis severity, guide percutaneous coronary intervention (PCI), and detect vulnerable plaques and patients. However, they have significant limitations that have stimulated the development of multimodality intracoronary imaging catheters, which provide improvements in assessing vessel wall pathology and guiding PCI. Prototypes combining 2 or even 3 imaging probes with complementary attributes have been developed, and several multimodality systems have already been used in patients, with near-infrared spectroscopy intravascular ultrasound-based studies showing promising results for the identification of high-risk plaques. Moreover, postmortem histology studies have documented that hybrid imaging catheters can enable more accurate characterization of plaque morphology than standalone imaging. This review describes the evolution in the field of hybrid intracoronary imaging; presents the available multimodality catheters; and discusses their potential role in PCI guidance, vulnerable plaque detection, and the assessment of endovascular devices and emerging pharmacotherapies targeting atherosclerosis.

A new understanding of coronary curvature and haemodynamic impact on the course of plaque onset and progression

The strong link between atherosclerosis and luminal biomechanical stresses is well established. Yet, this understanding has not translated into preventative coronary diagnostic imaging, particularly due to the under-explored role of coronary anatomy and haemodynamics in plaque onset, which we aim to address with this work. The left coronary trees of 20 non-stenosed (%diameter stenosis [%DS] = 0), 12 moderately (0 < %DS < 70) and 7 severely (%DS ≥ 70) stenosed cases were dissected into bifurcating and non-bifurcating segments for whole-tree and segment-specific comparisons, correlating nine three-dimensional coronary anatomical features, topological shear variation index (TSVI) and luminal areas subject to low time-average endothelial shear stress (%LowTAESS), high oscillatory shear index (%HighOSI) and high relative residence time (%HighRRT). We found that TSVI is the only metric consistently differing between non-stenosed and stenosed cases across the whole tree, bifurcating and non-bifurcating segments (p < 0.002, AUC = 0.876), whereas average curvature and %HighOSI differed only for the whole trees (p < 0.024) and non-bifurcating segments (p < 0.027), with AUC > 0.711. Coronary trees with moderate or severe stenoses differed only in %LowTAESS (p = 0.009) and %HighRRT (p = 0.012). This suggests TSVI, curvature and %HighOSI are potential factors driving plaque onset, with greater predictive performance than the previously recognized %LowTAESS and %HighRRT, which appears to play a role in plaque progression.

Role of the vessel morphology on the lenticulostriate arteries hemodynamics during atrial fibrillation: A CFD-based multivariate regression analysis

BACKGROUND AND OBJECTIVE

Atrial fibrillation (AF) is the most common cardiac arrhythmia, inducing accelerated and irregular beating. Beside well-known disabling symptoms - such as palpitations, reduced exercise tolerance, and chest discomfort - there is growing evidence that an alteration of deep cerebral hemodynamics due to AF increases the risk of vascular dementia and cognitive impairment, even in the absence of clinical strokes. The alteration of deep cerebral circulation in AF represents one of the least investigated among the possible mechanisms. Lenticulostriate arteries (LSAs) are small perforating arteries mainly departing from the middle cerebral artery (MCA) and susceptible to small vessel disease, which is one of the mechanisms of subcortical vascular dementia development. The purpose of this study is to investigate the impact of different LSAs morphologies on the cerebral hemodynamics during AF.

METHODS

By combining a computational fluid dynamics (CFD) analysis of LSAs with 7T high-resolution magnetic resonance imaging (MRI), we performed different CFD-based multivariate regression analyses to detect which geometrical and morphological vessel features mostly affect AF hemodynamics in terms of wall shear stress. We exploited 17 cerebral 7T-MRI derived LSA vascular geometries extracted from 10 subjects and internal carotid artery data from validated 0D cardiovascular-cerebral modeling as inflow conditions.

RESULTS

Our results revealed that few geometrical variables - namely the size of the MCA and the bifurcation angles between MCA and LSA - are able to satisfactorily predict the AF impact. In particular, the present study indicates that LSA morphologies exhibiting markedly obtuse LSA-MCA inlet angles and small MCA size downstream of the LSA-MCA bifurcation may be more prone to vascular damage induced by AF.

CONCLUSIONS

The present MRI-based computational study has been able for the first time to: (i) investigate the net impact of LSAs vascular morphologies on cerebral hemodynamics during AF events; (ii) detect which combination of morphological features worsens the hemodynamic response in the presence of AF. Awaiting necessary clinical confirmation, our analysis suggests that the local hemodynamics of LSAs is affected by their geometrical features and some LSA morphologies undergo greater hemodynamic alterations in the presence of AF.

Rapid prediction of wall shear stress in stenosed coronary arteries based on deep learning

There is increasing evidence that coronary artery wall shear stress (WSS) measurement provides useful prognostic information that allows prediction of adverse cardiovascular events. Computational Fluid Dynamics (CFD) has been extensively used in research to measure vessel physiology and examine the role of the local haemodynamic forces on the evolution of atherosclerosis. Nonetheless, CFD modelling remains computationally expensive and time-consuming, making its direct use in clinical practice inconvenient. A number of studies have investigated the use of deep learning (DL) approaches for fast WSS prediction. However, in these reports, patient data were limited and most of them used synthetic data generation methods for developing the training set. In this paper, we implement 2 approaches for synthetic data generation and combine their output with real patient data in order to train a DL model with a U-net architecture for prediction of WSS in the coronary arteries. The model achieved 6.03% Normalised Mean Absolute Error (NMAE) with inference taking only 0.35 s; making this solution time-efficient and clinically relevant.

Association Between Automated 3D Measurement of Coronary Luminal Narrowing and Risk of Future Myocardial Infarction

This study focuses on identifying anatomical markers with predictive capacity for long-term myocardial infarction (MI) in focal coronary artery disease (CAD). Eighty future culprit lesions (FCL) and 108 non-culprit lesions (NCL) from 80 patients underwent 3D quantitative coronary angiography. The minimum lumen area (MLA), minimum lumen ratio (MLR), and vessel fractional flow reserve (vFFR) were evaluated. MLR was defined as the ratio between MLA and the cross-sectional area at the proximal lesion edge, with lower values indicating more abrupt luminal narrowing. Significant differences were observed between FCL and NCL in MLR (0.41 vs. 0.53, p < 0.001). MLR correlated inversely with translesional vFFR (r =  - 0.26, p = 0.0004) and was the strongest predictor of MI at 5 years (AUC = 0.75). Lesions with MLR < 0.40 had a fourfold increased MI incidence at 5 years. MLR is a robust predictor of future adverse coronary events.

Biomechanical factors and atherosclerosis localization: insights and clinical applications

Although the entire vascular bed is constantly exposed to the same risk factors, atherosclerosis manifests a distinct intra-individual pattern in localization and progression within the arterial vascular bed. Despite shared risk factors, the development of atherosclerotic plaques is influenced by physical principles, anatomic variations, metabolic functions, and genetic pathways. Biomechanical factors, particularly wall shear stress (WSS), play a crucial role in atherosclerosis and both low and high WSS are associated with plaque progression and heightened vulnerability. Low and oscillatory WSS contribute to plaque growth and arterial remodeling, while high WSS promotes vulnerable changes in obstructive coronary plaques. Axial plaque stress and plaque structural stress are proposed as biomechanical indicators of plaque vulnerability, representing hemodynamic stress on stenotic lesions and localized stress within growing plaques, respectively. Advancements in imaging and computational fluid dynamics techniques enable a comprehensive analysis of morphological and hemodynamic properties of atherosclerotic lesions and their role in plaque localization, evolution, and vulnerability. Understanding the impact of mechanical forces on blood vessels holds the potential for developing shear-regulated drugs, improving diagnostics, and informing clinical decision-making in coronary atherosclerosis management. Additionally, Computation Fluid Dynamic (CFD) finds clinical applications in comprehending stent-vessel dynamics, complexities of coronary bifurcations, and guiding assessments of coronary lesion severity. This review underscores the clinical significance of an integrated approach, concentrating on systemic, hemodynamic, and biomechanical factors in atherosclerosis and plaque vulnerability among patients with coronary artery disease.

Application of optical coherence tomography in cardiovascular diseases: bibliometric and meta-analysis

Significance

Since the advent of Optical Coherence Tomography (OCT) two decades ago, there has been substantial advancement in our understanding of intravascular biology. Identifying culprit lesion pathology through OCT could precipitate a paradigm shift in the treatment of patients with Acute Coronary Syndrome. Given the technical prowess of OCT in the realm of cardiology, bibliometric analysis can reveal trends and research focal points in the application of OCT for cardiovascular diseases. Concurrently, meta-analyses provide a more comprehensive evidentiary base, supporting the clinical efficacy of OCT-guided Percutaneous Coronary Intervention (PCI).

Design

This study employs a dual approach of Bibliometric and Meta-analysis.

Methods

Relevant literature from 2003 to 2023 was extracted from the Web of Science Core Collection (WoSCC) and analyzed using VOSviewer, CiteSpace, and R for publication patterns, countries, institutions, authors, and research hotspots. The study compares OCT-guided and coronary angiography-guided PCI in treating adult coronary artery disease through randomized controlled trials (RCTs) and observational studies. The study has been reported in the line with PRISMA and AMSTAR Guidelines.

Results

Adhering to inclusion and exclusion criteria, 310 publications were incorporated, demonstrating a continual rise in annual output. Chinese researchers contributed the most studies, while American research wielded greater influence. Analysis of trends indicated that research on OCT and angiography-guided PCI has become a focal topic in recent cohort studies and RCTs. In 11 RCTs (n = 5,277), OCT-guided PCI was not significantly associated with a reduction in the risk of Major Adverse Cardiac Events (MACE) (Odds ratio 0.84, 95% CI 0.65-1.10), cardiac death (0.61, 0.36-1.02), all-cause death (0.7, 0.49-1.02), myocardial infarction (MI) (0.88, 0.69-1.13), target lesion revascularization (TLR) (0.94, 0.7-1.27), target vessel revascularization (TVR) (1.04, 0.76-1.43), or stent thrombosis (0.72, 0.38-1.38). However, in 7 observational studies (n = 4,514), OCT-guided PCI was associated with a reduced risk of MACE (0.66, 0.48-0.91) and TLR (0.39, 0.22-0.68).

Conclusion

Our comprehensive review of OCT in cardiovascular disease literature from 2004 to 2023, encompassing country and institutional origins, authors, and publishing journals, suggests that OCT-guided PCI does not demonstrate significant clinical benefits in RCTs. Nevertheless, pooled results from observational studies indicate a reduction in MACE and TLR.

The guardian of intracranial vessels: Why the pericyte?

Intracranial atherosclerotic stenosis (ICAS) is a pathological condition characterized by progressive narrowing or complete blockage of intracranial blood vessels caused by plaque formation. This condition leads to reduced blood flow to the brain, resulting in cerebral ischemia and hypoxia. Ischemic stroke (IS) resulting from ICAS poses a significant global public health challenge, especially among East Asian populations. However, the underlying causes of the notable variations in prevalence among diverse populations, as well as the most effective strategies for preventing and treating the rupture and blockage of intracranial plaques, remain incompletely comprehended. Rupture of plaques, bleeding, and thrombosis serve as precipitating factors in the pathogenesis of luminal obstruction in intracranial arteries. Pericytes play a crucial role in the structure and function of blood vessels and face significant challenges in regulating the Vasa Vasorum (VV)and preventing intraplaque hemorrhage (IPH). This review aims to explore innovative therapeutic strategies that target the pathophysiological mechanisms of vulnerable plaques by modulating pericyte biological function. It also discusses the potential applications of pericytes in central nervous system (CNS) diseases and their prospects as a therapeutic intervention in the field of biological tissue engineering regeneration.

Artificial intelligence-based quantitative coronary angiography of major vessels using deep-learning

BACKGROUND

Quantitative coronary angiography (QCA) offers objective and reproducible measures of coronary lesions. However, significant inter- and intra-observer variability and time-consuming processes hinder the practical application of on-site QCA in the current clinical setting. This study proposes a novel method for artificial intelligence-based QCA (AI-QCA) analysis of the major vessels and evaluates its performance.

METHODS

AI-QCA was developed using three deep-learning models trained on 7658 angiographic images from 3129 patients for the precise delineation of lumen boundaries. An automated quantification method, employing refined matching for accurate diameter calculation and iterative updates of diameter trend lines, was embedded in the AI-QCA. A separate dataset of 676 coronary angiography images from 370 patients was retrospectively analyzed to compare AI-QCA with manual QCA performed by expert analysts. A match was considered between manual and AI-QCA lesions when the minimum lumen diameter (MLD) location identified manually coincided with the location identified by AI-QCA. Matched lesions were evaluated in terms of diameter stenosis (DS), MLD, reference lumen diameter (RLD), and lesion length (LL).

RESULTS

AI-QCA exhibited a sensitivity of 89% in lesion detection and strong correlations with manual QCA for DS, MLD, RLD, and LL. Among 995 matched lesions, most cases (892 cases, 80%) exhibited DS differences ≤10%. Multiple lesions of the major vessels were accurately identified and quantitatively analyzed without manual corrections.

CONCLUSION

AI-QCA demonstrates promise as an automated tool for analysis in coronary angiography, offering potential advantages for the quantitative assessment of coronary lesions and clinical decision-making.

Vulnerable plaque features and adverse events in patients with diabetes mellitus: a post hoc analysis of the COMBINE OCT-FFR trial

BACKGROUND

Thin-cap fibroatheroma (TCFA) lesions are associated with a high risk of future major adverse cardiovascular events. However, the impact of other optical coherence tomography-detected vulnerability features (OCT-VFs) and their interplay with TCFA in predicting adverse events remains unknown.

AIMS

We aimed to evaluate the individual as well as the combined prognostic impact of OCT-VFs in predicting the incidence of the lesion-oriented composite endpoint (LOCE) in non-ischaemic lesions in patients with diabetes mellitus (DM).

METHODS

COMBINE OCT-FFR (ClinicalTrials.gov: NCT02989740) was a prospective, double-blind, international, natural history study that included DM patients with ≥1 non-culprit lesions with a fractional flow reserve>0.80 undergoing systematic OCT assessment. OCT-VFs included the following: TCFA, reduced minimal lumen area (r-MLA), healed plaque (HP), and complicated plaque (CP). The primary endpoint, LOCE - a composite of cardiac mortality, target vessel myocardial infarction, or clinically driven target lesion revascularisation up to 5 years - was analysed according to the presence of these OCT-VFs, both individually and in combination.

RESULTS

TCFA, r-MLA, HP and CP were identified in 98 (25.3%), 190 (49.0%), 87 (22.4%), and 116 (29.9%) patients, respectively. The primary endpoint rate increased progressively from 6.3% to 55.6% (hazard ratio 15.2, 95% confidence interval: 4.53-51.0; p<0.001) in patients without OCT-VFs as compared to patients with concomitant HP, r-MLA, CP, and TCFA. The coexistence of TCFA with other OCT-VFs resulted in an increased risk of the LOCE at 5 years.

CONCLUSIONS

In DM patients with non-ischaemic lesions, TCFA was the strongest predictor of future LOCE events. However, lesions that present additional OCT-VFs are associated with a higher risk of adverse events than OCT-detected TCFA alone. Further randomised studies are warranted to confirm these findings and their potential clinical implications.

Left anterior descending coronary artery-left circumflex coronary artery bifurcation angle and severity of coronary artery disease; is there any correlation? A cross-sectional study

Background and Aims

The aim of this study is to evaluate the association of coronary computed tomography angiography derived (CCTA) plaque characteristics and the left anterior descending coronary artery (LAD) and left circumflex coronary artery (LCX) bifurcation angle with severity of coronary artery disease (CAD).

Methods

All the stable patients with suspected CAD who underwent CCTA between January to December 2021 were included. Correlation between CCTA-derived aggregated plaque volume (APV), LAD-LCX angle, remodeling index (RI), coronary calcium score with Gensini score in conventional angiography were assessed. One hundred and twenty-two patients who underwent both CCTA and coronary angiography were analyzed.

Results

Our analysis showed that the median (percentile 25% to percentile 75%) of the APV, LAD-LCx angle, and calcium score were 31% (17%-47%), 58° (39°-89°), and 31 (0-186), respectively. Also, the mean ± SD of the RI was 1.05 ± 0.20. Significant correlation between LAD-LCx bifurcation angle (0.0001-0.684), APV (0.002-0.281), RI (0.0001-0.438), and calcium score (0.016-0.217) with Gensini score were detected. There was a linear correlation between the mean LAD-LCx bifurcation angle and the Gensini score. The sensitivity and specificity for the cut-off value of 47.5° for the LAD-LCX angle were 86.7% and 82.1%, respectively.

Conclusion

There is a direct correlation between the LAD-LCx angle and the Gensini score. In addition to plaque characteristics, anatomic-based CCTA-derived indices can be used to identify patients at higher risk for CAD.

Lack of Laminar Shear Stress Facilitates the Endothelial Uptake of Very Small Superparamagnetic Iron Oxide Nanoparticles by Modulating the Endothelial Surface Layer

Purpose

To study whether the absence of laminar shear stress (LSS) enables the uptake of very small superparamagnetic iron oxide nanoparticles (VSOP) in endothelial cells by altering the composition, size, and barrier function of the endothelial surface layer (ESL).

Methods and Results

A quantitative particle exclusion assay with living human umbilical endothelial cells using spinning disc confocal microscopy revealed that the dimension of the ESL was reduced in cells cultivated in the absence of LSS. By combining gene expression analysis, flow cytometry, high pressure freezing/freeze substitution immuno-transmission electron microscopy, and confocal laser scanning microscopy, we investigated changes in ESL composition. We found that increased expression of the hyaluronan receptor CD44 by absence of shear stress did not affect the uptake rate of VSOPs. We identified collagen as a previously neglected component of ESL that contributes to its barrier function. Experiments with inhibitor halofuginone and small interfering RNA (siRNA) demonstrated that suppression of collagen expression facilitates VSOP uptake in endothelial cells grown under LSS.

Conclusion

The absence of laminar shear stress disturbs the barrier function of the ESL, facilitating membrane accessibility and endocytic uptake of VSOP. Collagen, a previously neglected component of ESL, contributes to its barrier function.

Impact of triglyceride-glucose index on intracoronary thrombus burden in ST-elevation myocardial infarction patients undergoing primary percutaneous coronary intervention

BACKGROUND AND AIMS

We aimed to investigate the relationship between triglyceride glucose (TyG) index and intracoronary thrombus burden in patients with ST-elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

A total of 468 consecutive patients who were admitted with STEMI and underwent primary PCI were included in the study. TyG index was calculated as ln [fasting triglycerides (mg/dL) × fasting plasma glucose (mg/dL)/2]. According to the angiographic reclassified thrombolysis in myocardial infarction (TIMI) thrombus grade, patients were divided into two groups as small thrombus burden (STB) with TIMI thrombus grade 0-3, and large thrombus burden (LTB) with TIMI thrombus grade 4-5. TyG index was significantly higher in the LTB group than in the STB group (9.11 ± 0.86 vs 8.89 ± 0.62; p = 0.002). In multivariate analysis, TyG index was found to be an independent predictor of LTB in STEMI patients who underwent primary PCI [OR (95 % CI): 1.470 (1.090-1.982), p = 0.012]. The area under the curve (AUC) of TyG index predicting LTB was 0.568 (95 % CI 0.506-0.631; p = 0.023), with the best cut-off value of 8.87. In the classification according to TyG index cut-off value, the frequency of LTB was found to be significantly higher in the high TyG index group than in the low TyG index group (33.6 % vs 21.2 %; p = 0.003).

CONCLUSION

TyG index, a valid surrogate marker of insulin resistance, is an independent predictor of LTB in STEMI patients who underwent primary PCI and can be used as an indicator of increased intracoronary thrombus burden.

Pancoronary plaque characteristics in STEMI patients with rapid plaque progression: An optical coherence tomography study

BACKGROUND

Non-culprit plaque progression is associated with recurrent cardiac ischemic events and worse clinical outcomes. Given that atherosclerosis is a systemic disease, the pancoronary characteristics of patients with rapid plaque progression are unknown. This study aims to identify pancoronary plaque features in patients with ST-segment elevation myocardial infarction (STEMI) with and without rapid plaque progression, focused on the patient level.

METHODS AND RESULTS

From January 2017 to July 2019, 291 patients underwent 3-vessel optical coherence tomography imaging at the time of the primary procedure and a follow-up angiography interval of 12 months. The final analysis included 237 patients. Overall, 308 non-culprit lesions were found in 78 STEMI patients with rapid plaque progression, and 465 non-culprit plaques were found in 159 STEMI patients without rapid plaque progression. These patients had a higher pancoronary vulnerability (CLIMA-defined high-risk plaque: 47.4% vs. 33.3%; non-culprit plaque rupture: 25.6% vs. 14.5%) and a significantly higher prevalence of other vulnerable plaque characteristics (i.e., lipid-rich plaque, cholesterol crystal, microchannels, calcification, spotty calcification, and thrombus) at baseline versus those without rapid plaque progression. Lesions with rapid progression were highly distributed at the LAD, tending to be near the bifurcation. In multivariate analysis, age ≥ 65 years was an independent predictor of subsequent rapid lesion progression at the patient level, whereas microchannel, spotty calcification, and cholesterol crystal were independent predictors for STEMI patients ≥65 years old.

CONCLUSIONS

STEMI patients with subsequent rapid plaque progression had higher pancoronary vulnerability and commonly presented vulnerable plaque morphology. Aging was the only predictor of subsequent rapid plaque progression.

Non-Invasive Assessment of Endothelial Shear Stress in Myocardial Bridges Using Coronary Computed Tomography Angiography

Myocardial bridging (MB) is a segment of coronary arteries with an intramural course, typically spared from atherosclerosis, while the adjacent proximal segment is reported to be atherosclerosis-prone, a phenomenon contributed to local endothelial shear stress (ESS). We aimed to describe the ESS milieu in coronaries with MBs combining coronary computed tomography angiography with computational fluid dynamics and to investigate the association of atherosclerosis presence proximal to MBs with hemorheological characteristics. Patients (n = 36) were identified and 36 arteries with MBs (11 deep and 25 superficial) were analyzed. ESS did not fluctuate 5 mm proximally to MBs vs 5 mm within MBs (0.94 vs 1.06 Pa, p = .56). There was no difference when comparing ESS in the proximal versus mid versus distal MB segments (1.48 vs 1.37 vs 1.9 Pa, p = ns). In arteries with plaques (n = 12), no significant ESS variances were observed around the MB entrance, when analyzing all arteries (p = .81) and irrespective of morphological features of the bridged segment (deep MBs; p = .65, superficial MBs; p = .84). MBs are characterized by homogeneous, atheroprotective ESS, possibly explaining the absence of atherosclerosis within bridged segments. The interplay between ESS and atherosclerosis is potentially not different in arteries with MB compared with arteries without bridges.

Predicting Lipid-Rich Plaque Progression in Coronary Arteries Using Multimodal Imaging and Wall Shear Stress Signatures

BACKGROUND

Plaque composition and wall shear stress (WSS) magnitude act as well-established players in coronary plaque progression. However, WSS magnitude per se does not completely capture the mechanical stimulus to which the endothelium is subjected, since endothelial cells experience changes in the WSS spatiotemporal configuration on the luminal surface. This study explores WSS profile and lipid content signatures of plaque progression to identify novel biomarkers of coronary atherosclerosis.

METHODS

Thirty-seven patients with acute coronary syndrome underwent coronary computed tomography angiography, near-infrared spectroscopy intravascular ultrasound, and optical coherence tomography of at least 1 nonculprit vessel at baseline and 1-year follow-up. Baseline coronary artery geometries were reconstructed from intravascular ultrasound and coronary computed tomography angiography and combined with flow information to perform computational fluid dynamics simulations to assess the time-averaged WSS magnitude (TAWSS) and the variability in the contraction/expansion action exerted by WSS on the endothelium, quantifiable in terms of topological shear variation index (TSVI). Plaque progression was measured as intravascular ultrasound-derived percentage plaque atheroma volume change at 1-year follow-up. Plaque composition information was extracted from near-infrared spectroscopy and optical coherence tomography.

RESULTS

Exposure to high TSVI and low TAWSS was associated with higher plaque progression (4.00±0.69% and 3.60±0.62%, respectively). Plaque composition acted synergistically with TSVI or TAWSS, resulting in the highest plaque progression (≥5.90%) at locations where lipid-rich plaque is exposed to high TSVI or low TAWSS.

CONCLUSIONS

Luminal exposure to high TSVI, solely or combined with a lipid-rich plaque phenotype, is associated with enhanced plaque progression at 1-year follow-up. Where plaque progression occurred, low TAWSS was also observed. These findings suggest TSVI, in addition to low TAWSS, as a potential biomechanical predictor for plaque progression, showing promise for clinical translation to improve patient prognosis.

Influence of intracoronary hemodynamic forces on atherosclerotic plaque phenotypes

BACKGROUND AND AIMS

Coronary hemodynamics impact coronary plaque progression and destabilization. The aim of the present study was to establish the association between focal vs. diffuse intracoronary pressure gradients and wall shear stress (WSS) patterns with atherosclerotic plaque composition.

METHODS

Prospective, international, single-arm study of patients with chronic coronary syndromes and hemodynamic significant lesions (fractional flow reserve [FFR] ≤ 0.80). Motorized FFR pullback pressure gradient (PPG), optical coherence tomography (OCT), and time-average WSS (TAWSS) and topological shear variation index (TSVI) derived from three-dimensional angiography were obtained.

RESULTS

One hundred five vessels (median FFR 0.70 [Interquartile range (IQR) 0.56-0.77]) had combined PPG and WSS analyses. TSVI was correlated with PPG (r = 0.47, [95% Confidence Interval (95% CI) 0.30-0.65], p < 0.001). Vessels with a focal CAD (PPG above the median value of 0.67) had significantly higher TAWSS (14.8 [IQR 8.6-24.3] vs. 7.03 [4.8-11.7] Pa, p < 0.001) and TSVI (163.9 [117.6-249.2] vs. 76.8 [23.1-140.9] m-1, p < 0.001). In the 51 vessels with baseline OCT, TSVI was associated with plaque rupture (OR 1.01 [1.00-1.02], p = 0.024), PPG with the extension of lipids (OR 7.78 [6.19-9.77], p = 0.003), with the presence of thin-cap fibroatheroma (OR 2.85 [1.11-7.83], p = 0.024) and plaque rupture (OR 4.94 [1.82 to 13.47], p = 0.002).

CONCLUSIONS

Focal and diffuse coronary artery disease, defined using coronary physiology, are associated with differential WSS profiles. Pullback pressure gradients and WSS profiles are associated with atherosclerotic plaque phenotypes. Focal disease (as identified by high PPG) and high TSVI are associated with high-risk plaque features.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials,gov/ct2/show/NCT03782688.

Comprehensive biomechanical and anatomical atherosclerotic plaque metrics predict major adverse cardiovascular events: A new tool for clinical decision making

BACKGROUND AND AIMS

Anatomical imaging alone of coronary atherosclerotic plaques is insufficient to identify risk of future adverse events and guide management of non-culprit lesions. Low endothelial shear stress (ESS) and high plaque structural stress (PSS) are associated with events, but individually their predictive value is insufficient for risk prediction. We determined whether combining multiple complementary, biomechanical and anatomical plaque characteristics improves outcome prediction sufficiently to inform clinical decision-making.

METHODS

We examined baseline ESS, ESS gradient (ESSG), PSS, and PSS heterogeneity index (HI), and plaque burden in 22 lesions that developed subsequent events and 64 control lesions that remained quiescent from the PROSPECT study.

RESULTS

86 fibroatheromas were analysed from 67 patients. Lesions with events showed higher PSS HI (0.32 vs. 0.24, p<0.001), lower local ESS (0.56Pa vs. 0.91Pa, p = 0.007), and higher ESSG (3.82 Pa/mm vs. 1.96 Pa/mm, p = 0.007), while high PSS HI (hazard ratio [HR] 3.9, p = 0.006), high ESSG (HR 3.4, p = 0.007) and plaque burden>70 % (HR 2.6, p = 0.02) were independent outcome predictors in multivariate analysis. Combining low ESS, high ESSG, and high PSS HI gave both high positive predictive value (80 %), which increased further combined with plaque burden>70 %, and negative predictive value (81.6 %). Low ESS, high ESSG, and high PSS HI co-localised spatially within 1 mm in lesions with events, and importantly, this cluster was distant from the minimum lumen area site.

CONCLUSIONS

Combining complementary biomechanical and anatomical metrics significantly improves risk-stratification of individual coronary lesions. If confirmed from larger prospective studies, our results may inform targeted revascularisation vs. conservative management strategies.

Association of Coronary Artery Severity and Late In-Stent Restenosis: An Angiographic Imaging Study

Coronary in-stent restenosis (ISR) remains a challenge in interventional cardiology. We investigated the relationship between angiographic pre-interventional grade of lesion stenosis (LS) and the prognosis of late ISR. After exclusions, 110 patients with ISR and 109 patients without ISR were compared. In the ISR group, the grade of LS was greater (P < .001) and the length of the critical segment (LCS) was longer (P < .001). Stent length was longer in the ISR group (P = .008). Compared with the LCS, the grade of LS above 87.5% is 6.9 times more predictive of ISR than the LCS >10.5 mm. Kaplan-Meier curve analysis showed that the grade of initial LS >87.5% had a higher ISR rate than the grade of LS <87.5% (log-rank test P < .001) and critical lesion length over 10.5 mm had a higher ISR rate than critical lesion length under 10.5 mm (log-rank test P < .001). The present study found that the angiographic pre-interventional grades of LS and LCS were important predictors of ISR. Pre-interventional angiographic stenosis >87.5% was significantly predictive of late ISR.

Talin mechanotransduction in disease

Talin protein (Talin 1/2) is a mechanosensitive cytoskeleton protein. The unique structure of the Talin plays a vital role in transmitting mechanical forces. Talin proteins connect the extracellular matrix to the cytoskeleton by linking to integrins and actin, thereby mediating the conversion of mechanical signals into biochemical signals and influencing disease progression as potential diagnostic indicators, therapeutic targets, and prognostic indicators of various diseases. Most studies in recent years have confirmed that mechanical forces also have a crucial role in the development of disease, and Talin has been found to play a role in several diseases. Still, more studies need to be done on how Talin is involved in mechanical signaling in disease. This review focuses on the mechanical signaling of Talin in disease, aiming to summarize the mechanisms by which Talin plays a role in disease and to provide references for further studies.

Exercise-based cardiac rehabilitation in stable angina pectoris: a narrative review on current evidence and underlying physiological mechanisms

Stable angina pectoris (SAP) is a prevalent condition characterised by a high disease burden. Based on recent evidence, the need for revascularisation in addition to optimal medical treatment to reduce mortality and re-events is heavily debated. These observations may be explained by the fact that revascularisation is targeted at the local flow-limiting coronary artery lesion, while the aetiology of SAP relates to the systemic, inflammatory process of atherosclerosis, causing generalised vascular dysfunction throughout the entire vascular system. Moreover, cardiovascular events are not solely caused by obstructive plaques but are also associated with plaque burden and high-risk plaque features. Therefore, to reduce the risk of cardiovascular events and angina, and thereby improve quality of life, alternative therapeutic approaches to revascularisation should be considered, preferably targeting the cardiovascular system as a whole with a physiological approach. Exercise-based cardiac rehabilitation fits this description and is a promising strategy as a first-line treatment in addition to optimal medical treatment. In this review, we discuss the role of exercise-based cardiac rehabilitation in SAP in relation to the underlying physiological mechanisms, we summarise the existing evidence and highlight future directions.

Software that combines deep learning, 3D reconstruction and CFD to analyze the state of carotid arteries from ultrasound imaging

BACKGROUND

Ultrasound is one of the non-invasive techniques that are used in clinical diagnostics of carotid artery disease.

OBJECTIVE

This paper presents software methodology that can be used in combination with this imaging technique to provide additional information about the state of patient-specific artery.

METHODS

Overall three modules are combined within the proposed methodology. A clinical dataset is used within the deep learning module to extract the contours of the carotid artery. This data is then used within the second module to perform the three-dimensional reconstruction of the geometry of the carotid bifurcation and ultimately this geometry is used within the third module, where the hemodynamic analysis is performed. The obtained distributions of hemodynamic quantities enable a more detailed analysis of the blood flow and state of the arterial wall and could be useful to predict further progress of present abnormalities in the carotid bifurcation.

RESULTS

The performance of the deep learning module was demonstrated through the high values of relevant common classification metric parameters. Also, the accuracy of the proposed methodology was shown through the validation of results for the reconstructed parameters against the clinically measured values.

CONCLUSION

The presented methodology could be used in combination with standard clinical ultrasound examination to quickly provide additional quantitative and qualitative information about the state of the patient's carotid bifurcation and thus ensure a treatment that is more adapted to the specific patient.

Mechanical wall stress and wall shear stress are associated with atherosclerosis development in non-calcified coronary segments

BACKGROUND AND AIMS

Atherosclerotic plaque onset and progression are known to be affected by local biomechanical factors. While the role of wall shear stress (WSS) has been studied, the impact of another biomechanical factor, namely mechanical wall stress (MWS), remains poorly understood. In this study, we investigated the association of MWS, independently and combined with WSS, towards atherosclerosis in coronary arteries.

METHODS

Thirty-four human coronary arteries were analyzed using near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) and optical coherence tomography (OCT) at baseline and after 12 months. Baseline WSS and MWS were calculated using computational models, and wall thickness (ΔWT) and lipid-rich necrotic core size (ΔLRNC) change were measured in non-calcified coronary segments. The arteries were further divided into 1.5 mm/45° sectors and categorized as plaque-free or plaque sectors. For each category, associations between biomechanical factors (WSS & MWS) and changes in coronary wall (ΔWT & ΔLRNC) were studied using linear mixed models.

RESULTS

In plaque-free sectors, higher MWS (p < 0.001) was associated with greater vessel wall growth. Plaque sectors demonstrated wall thickness reduction over time, likely due to medical therapy, where higher levels of WSS and WMS, individually and combined, (p < 0.05) were associated with a greater reduction. Sectors with low MWS combined with high WSS demonstrated the highest LRNC increase (p < 0.01).

CONCLUSIONS

In this study, we investigated the association of the (largely-overlooked) biomechanical factor MWS with coronary atherosclerosis, individually and combined with WSS. Our results demonstrated that both MWS and WSS significantly correlate with atherosclerotic plaque initiation and development.

Selective ensemble methods for deep learning segmentation of major vessels in invasive coronary angiography

BACKGROUND

Invasive coronary angiography (ICA) is a primary imaging modality that visualizes the lumen area of coronary arteries for diagnosis and interventional guidance. In the current practice of quantitative coronary analysis (QCA), semi-automatic segmentation tools require labor-intensive and time-consuming manual correction, limiting their application in the catheterization room.

PURPOSE

This study aims to propose rank-based selective ensemble methods that improve the segmentation performance and reduce morphological errors that limit fully automated quantification of coronary artery using deep-learning segmentation of ICA.

METHODS

Two selective ensemble methods proposed in this work integrated the weighted ensemble approach with per-image quality estimation. The segmentation outcomes from five base models with different loss functions were ranked either by mask morphology or estimated dice similarity coefficient (DSC). The final output was determined by imposing different weights according to the ranks. The ranking criteria based on mask morphology were formulated from empirical insight to avoid frequent types of segmentation errors (MSEN), while the estimation of DSCs was performed by comparing the pseudo-ground truth generated from a meta-learner (ESEN). Five-fold cross-validation was performed with the internal dataset of 7426 coronary angiograms from 2924 patients, and prediction model was externally validated with 556 images of 226 patients.

RESULTS

The selective ensemble methods improved the segmentation performance with DSCs up to 93.07% and provided a better delineation of coronary lesion with local DSCs of up to 93.93%, outperforming all individual models. Proposed methods also minimized the chances of mask disconnection in the most narrowed regions to 2.10%. The robustness of the proposed methods was also evident in the external validation. Inference time for major vessel segmentation was approximately one-sixth of a second.

CONCLUSION

Proposed methods successfully reduced morphological errors in the predicted masks and were able to enhance the robustness of the automatic segmentation. The results suggest better applicability of real-time QCA-based diagnostic methods in routine clinical settings.

High blood viscosity in acute ischemic stroke

Background

The changes in blood viscosity can influence the shear stress at the vessel wall, but there is limited evidence regarding the impact on thrombogenesis and acute stroke. We aimed to investigate the effect of blood viscosity on stroke and the clinical utility of blood viscosity measurements obtained immediately upon hospital arrival.

Methods

Patients with suspected stroke visiting the hospital within 24 h of the last known well time were enrolled. Point-of-care testing was used to obtain blood viscosity measurements before intravenous fluid infusion. Blood viscosity was measured as the reactive torque generated at three oscillatory frequencies (1, 5, and 10 rad/sec). Blood viscosity results were compared among patients with ischemic stroke, hemorrhagic stroke, and stroke mimics diagnosed as other than stroke.

Results

Among 112 enrolled patients, blood viscosity measurements were accomplished within 2.4 ± 1.3 min of vessel puncture. At an oscillatory frequency of 10 rad/sec, blood viscosity differed significantly between the ischemic stroke (24.2 ± 4.9 centipoise, cP) and stroke mimic groups (17.8 ± 6.5 cP, p < 0.001). This finding was consistent at different oscillatory frequencies (134.2 ± 46.3 vs. 102.4 ± 47.2 at 1 rad/sec and 39.2 ± 11.5 vs. 30.4 ± 12.4 at 5 rad/sec, Ps < 0.001), suggesting a relationship between decreases in viscosity and shear rate. The area under the receiver operating curve for differentiating cases of stroke from stroke mimic was 0.79 (95% confidence interval, 0.69-0.88).

Conclusion

Patients with ischemic stroke exhibit increases in whole blood viscosity, suggesting that blood viscosity measurements can aid in differentiating ischemic stroke from other diseases.

Multislice computerized tomography coronary angiography can be a comparable tool to intravascular ultrasound in evaluating "true" coronary artery bifurcations

Aim

Coronary bifurcation atherosclerosis depends on its angles, flow, and extensive branching. We investigate the ability of CT coronary angiography (CTCA) to determine atherosclerotic plaque characteristics of "true" bifurcation compared with intravascular ultrasound (IVUS) and the influence on side branch (SB) fate after percutaneous coronary intervention (PCI).

Methods and results

The study included 70 patients with 72 "true" bifurcations. Most of the bifurcations were in the left anterior descending-diagonal (Dg) territory [50 out of 72 (69.4%)]. Longitudinal plaque evaluation at the polygon of confluence [carina and 5 mm proximal and distal in the main branch (MB)] showed that carina side MB and SB plaque had occurred with the lowest incidence with fibro-lipid structure (115 ± 63 HU and 89 ± 73 HU, p < 0.001 for all). Bland-Altman analysis showed a discrepancy in measuring mainly the lumen area between CTCA and IVUS in proximal MB [lumen 5.10, 95% CI (95% confidence interval, 4.53-5.68) mm2, p < 0.001; vessel -1.42, 95% CI (-2.63 to -0.21) mm2, p = 0.023], carina MB [lumen 3.74, 95% CI (3.37-4.10) mm2, p < 0.001; vessel -0.48, 95% CI (-1.45 to 0.48) mm2, p = 0.322], and distal MB [lumen 4.72, 95% CI (4.27-5.18) mm2, p < 0.001; vessel 0.62, 95% CI (-0.53 to 1.77) mm2, p = 0.283]. A significant correlation existed between average plaque density on CTCA with a percentage of calcified plaque on IVUS tissue characterization (proximal r = 0.307/p = 0.024, carina 0.469/0.008, distal 0.339/0.024, minimal lumen diameter 0.318/0.020). Circumferential plaque in the proximal MB segment remained an independent predictor of SB compromise [OR 3.962 (95% CI 1.170-13.418)].

Conclusion

Detection and characterization of atherosclerotic plaque by CTCA in non-left main "true" coronary bifurcations can provide useful information about bifurcation anatomy and plaque distribution that can predict outcomes after provisional stenting, thus guiding the interventional strategy to bifurcation PCI.

The plaque hypothesis: understanding mechanisms of plaque progression and destabilization, and implications for clinical management

PURPOSE OF REVIEW

Major adverse cardiac events (MACE) typically arise from nonflow-limiting coronary artery disease and not from flow-limiting obstructions that cause ischemia. This review elaborates the current understanding of the mechanism(s) for plaque development, progression, and destabilization and how identification of these high-risk features can optimally inform clinical management.

RECENT FINDINGS

Advanced invasive and noninvasive coronary imaging and computational postprocessing enhance an understanding of pathobiologic/pathophysiologic features of coronary artery plaques prone to destabilization and MACE. Early investigations of high-risk plaques focused on anatomic and biochemical characteristics (large plaque burden, severe luminal obstruction, thin cap fibroatheroma morphology, and large lipid pool), but more recent studies underscore that additional factors, particularly biomechanical factors [low endothelial shear stress (ESS), high ESS gradient, plaque structural stress, and axial plaque stress], provide the critical incremental stimulus acting on the anatomic substrate to provoke plaque destabilization. These destabilizing features are often located in areas distant from the flow-limiting obstruction or may exist in plaques without any flow limitation. Identification of these high-risk, synergistic plaque features enable identification of plaques prone to destabilize regardless of the presence or absence of a severe obstruction (Plaque Hypothesis).

SUMMARY

Local plaque topography, hemodynamic patterns, and internal plaque constituents constitute high-risk features that may be located along the entire course of the coronary plaque, including both flow-limiting and nonflow-limiting regions. For coronary interventions to have optimal clinical impact, it will be critical to direct their application to the plaque area(s) at highest risk.

Angiography and optical coherence tomography derived shear stress: are they equivalent in my opinion?

Advances in image reconstruction using either single or multimodality imaging data provide increasingly accurate three-dimensional (3D) patient's arterial models for shear stress evaluation using computational fluid dynamics (CFD). We aim to evaluate the impacts on endothelial shear stress (ESS) derived from a simple image reconstruction using 3D-quantitative coronary angiography (3D-QCA) versus a multimodality reconstruction method using optical coherence tomography (OCT) in patients' vessels treated with bioresorbable scaffolds. Seven vessels at baseline and five-year follow-up of seven patients from a previous CFD investigation were retrospectively selected for a head-to-head comparison of angiography-derived versus OCT-derived ESS. 3D-QCA significantly underestimated the minimum stent area [MSA] (-2.38mm2) and the stent length (-1.46 mm) compared to OCT-fusion method reconstructions. After carefully co-registering the region of interest for all cases with a sophisticated statistical method, the difference in MSA measurements as well as the inability of angiography to visualise the strut footprint in the lumen surface have translated to higher angiography-derived ESS than OCT-derived ESS (1.76 Pa or 1.52 times for the overlapping segment). The difference in ESS widened with a more restricted region of interest (1.97 Pa or 1.63 times within the scaffold segment). Angiography and OCT offer two distinctive methods of ESS calculation. Angiography-derived ESS tends to overestimate the ESS compared to OCT-derived ESS. Further investigations into ESS analysis resolution play a vital role in adopting OCT-derived ESS.