Symptomatic Carotid Atherosclerotic Plaques Research Articles

Improving radiomic modeling for the identification of symptomatic carotid atherosclerotic plaques using deep learning-based 3D super-resolution CT angiography

Rationale and objectivesRadiomic models based on normal-resolution (NR) computed tomography angiography (CTA) images can fail to distinguish between symptomatic and asymptomatic carotid atherosclerotic plaques. This study aimed to explore the effectiveness of a deep learning-based three-dimensional super-resolution (SR) CTA radiomic model for improved identification of symptomatic carotid atherosclerotic plaques. Materials and methodsA total of 193 patients with carotid atherosclerotic plaques were retrospectively enrolled and allocated into either a symptomatic (n = 123) or an asymptomatic (n = 70) groups. SR CTA images were derived from NR CTA images using deep learning-based three-dimensional SR technology. Handcrafted radiomic features were extracted from both the SR and NR CTA images and three risk models were developed based on manually measured quantitative CTA characteristics and NR and SR radiomic features. Model performances were assessed via receiver operating characteristic, calibration, and decision curve analyses. ResultsThe SR model exhibited the optimal performance (area under the curve [AUC] 0.820, accuracy 0.802, sensitivity 0.854, F1 score 0.847) in the testing cohort, outperforming the other two models. The calibration curve analyses and Hosmer–Lemeshow test demonstrated that the SR model exhibited the best goodness of fit, and decision curve analysis revealed that SR model had the highest clinical value and potential patient benefits. ConclusionsDeep learning-based three-dimensional SR technology could improve the CTA-based radiomic models in identifying symptomatic carotid plaques, potentially providing more accurate and valuable information to guide clinical decision-making to reduce the risk of ischemic stroke.

Single-nucleus RNA sequencing reveals that macrophages and smooth muscle cells promote carotid atherosclerosis progression through mitochondrial autophagy.

Carotid atherosclerotic plaques are the manifestation of atherosclerosis in the carotid arteries and can significantly increase the incidence of cerebrovascular disease. Macrophages and smooth muscle cells are crucial for their development. To reveal the mechanism of carotid atherosclerotic plaque formation, we performed single-nucleus RNA sequencing of the carotid plaque tissue and identified 11 cell types, and the macrophages were divided into 5 different macrophage subpopulations. The macrophages and smooth muscle cells in the patients with symptomatic carotid atherosclerotic plaques caused intraplaque cell death via the mitochondrial autophagic pathway, resulting in plaque instability and rupture, which in turn led to clinical cardiovascular and cerebrovascular events. The findings provide new insights into carotid atherosclerosis formation, and this may provide new directions for the prevention and treatment of carotid atherosclerosis.

Characteristics of the gut microbiota of patients with symptomatic carotid atherosclerotic plaques positive for bacterial genetic material.

The gut microbiota (GM) is believed to be closely associated with symptomatic carotid atherosclerosis (SCAS), yet more evidence is needed to substantiate the significant role of GM in SCAS. This study, based on the detection of bacterial DNA in carotid plaques, explores the characteristics of GM in SCAS patients with plaque bacterial genetic material positivity, aiming to provide a reference for subsequent research. We enrolled 27 healthy individuals (NHF group) and 23 SCAS patients (PFBS group). We utilized 16S rDNA V3-V4 region gene sequencing to analyze the microbiota in fecal samples from both groups, as well as in plaque samples from the carotid bifurcation extending to the origin of the internal carotid artery in all patients. Our results indicate significant differences in the gut microbiota (GM) between SCAS patients and healthy individuals. The detection rate of bacterial DNA in plaque samples was approximately 26%. Compared to patients with negative plaques (PRSOPWNP group), those with positive plaques (PRSOPWPP group) exhibited significant alterations in their GM, particularly an upregulation of 11 bacterial genera (such as Klebsiella and Streptococcus) in the gut, which were also present in the plaques. In terms of microbial gene function prediction, pathways such as Fluorobenzoate degradation were significantly upregulated in the GM of patients with positive plaques. In summary, our study is the first to identify significant alterations in the gut microbiota of patients with positive plaques, providing crucial microbial evidence for further exploration of the pathogenesis of SCAS.

Increased Piezo1 expression in myofibroblasts in patients with symptomatic carotid atherosclerotic plaques undergoing carotid endarterectomy: A pilot study.

We aimed to investigate Piezo1 expression in myofibroblasts in symptomatic and asymptomatic patients undergoing carotid endarterectomy and its relationship with atherosclerotic plaque formation. This cross-sectional study analyzed carotid plaques of 17 randomly selected patients who underwent carotid endarterectomy from May 2015 to August 2017. In total, 51 sections (the most stenotic lesion, and the sections 5-mm proximal and distal) stained with hematoxylin-eosin and elastica-Masson were examined. Immunohistochemistry was performed using antibodies to Piezo1. The Piezo1 score of a section was calculated semiquantitatively, averaged across 30 randomly selected myofibroblasts in the fibrous cap of the plaque. Of 17 patients (mean age: 74.2 ± 7.1 years), 15 were men, 9 had diabetes mellitus, and 13 had hypertension. Symptomatic patients had higher mean Piezo1 score than asymptomatic patients (1.78 ± 0.23 vs 1.34 ± 0.17, p < .001). Univariate linear regression analyses suggested an association between plaque rupture, thin-cap fibroatheroma and microcalcifications and the Piezo1 score (p = .001, .008, and 0.003, respectively). Increased Piezo1 expression of myofibroblasts may be associated with atherosclerotic carotid plaque instability. Further study is warranted to support this finding.

Machine learning-based identification of symptomatic carotid atherosclerotic plaques with dual-energy computed tomography angiography

ObjectiveThis study aimed to develop and validate a machine learning model incorporating both dual-energy computed tomography (DECT) angiography quantitative parameters and clinically relevant risk factors for the identification of symptomatic carotid plaques to prevent acute cerebrovascular events. MethodsThe data of 180 patients with carotid atherosclerosis plaques were analysed from January 2017 to December 2021; 110 patients (64.03±9.58 years old, 20 women, 90 men) were allocated to the symptomatic group, and 70 patients (64.70±9.89 years old, 50 women, 20 men) were allocated to the asymptomatic group. Overall, five machine learning models using the XGBoost algorithm, based on different CT and clinical features, were developed in the training cohort. The performances of all five models were assessed in the testing cohort using receiver operating characteristic curves, accuracy, recall rate, and F1 score. ResultsThe shapley additive explanation (SHAP) value ranking showed fat fraction (FF) as the highest among all CT and clinical features and normalised iodine density (NID) as the 10th. The model based on the top 10 features from the SHAP measurement showed optimal performance (area under the curve [AUC] .885, accuracy .833, recall rate .933, F1 score .861), compared with the other four models based on conventional CT features (AUC .588, accuracy .593, recall rate .767, F1 score .676), DECT features (AUC .685, accuracy .648, recall rate .667, F1 score .678), conventional CT and DECT features (AUC .819, accuracy .740, recall rate .867, F1 score .788), and all CT and clinical features (AUC .878, accuracy .833, recall rate .867, F1 score .852). ConclusionFF and NID can serve as useful imaging markers of symptomatic carotid plaques. This tree-based machine learning model incorporating both DECT and clinical features could potentially comprise a non-invasive method for identification of symptomatic carotid plaques to guide clinical treatment strategies.

Clinical Application of High-Frame-Rate Vector Flow Imaging in Evaluation of Carotid Atherosclerotic Stenosis.

This study seeks to evaluate the value of the high-frame-rate vector flow imaging technique in assessing the hemodynamic changes of carotid atherosclerotic stenosis in aging people (>60 years old). Aging patients diagnosed with carotid atherosclerotic stenosis who underwent carotid high-frame-rate vector flow imaging examination were prospectively enrolled. A Mindray Resona7s ultrasound machine equipped with high-frame-rate vector flow function was used for ultrasound evaluation. First, B mode ultrasound and color Doppler flow imaging were used to evaluate carotid stenosis. Then, the vector arrows and flow streamline detected by V Flow were analyzed and the wall shear stress values (Pa) at the carotid stenosis site were measured. All patients were divided into symptomatic and asymptomatic groups according to whether they had acute/subacute stroke or other clinical symptoms within 2 weeks before ultrasound examination. The results of digital subtraction angiography or computed tomography angiography were used as the gold standard. The stenosis rate was calcified, according to North American Symptomatic Carotid Endarterectomy Trial criteria. The diagnostic values of wall shear stress, conventional ultrasound, and the combined diagnosis in carotid atherosclerotic stenosis were compared. Finally, 88 patients with carotid atherosclerotic plaque were enrolled (71 males (80.7%), mean age 67.6 ± 5.4 years). The success rate of high-frame-rate vector flow imaging was 96.7% (88/91). The WSS value of symptomatic carotid stenosis (1.4 ± 0.15 Pa) was significantly higher than that of asymptomatic carotid stenosis (0.80 ± 0.08 Pa) (p < 0.05). Taking the wall shear stress value > 0.78 Pa as the diagnostic criteria for symptomatic carotid atherosclerotic plaque, the area under receiver operating characteristic curves was 0.79 with 87.1% sensitivity and 69.6% specificity. The area under receiver operating characteristic curves of the combined diagnosis (0.966) for differentiating severe carotid atherosclerotic stenosis was significantly higher than that of conventional ultrasound and WSS value, with 89.7% sensitivity and 93.2% specificity (p < 0.05). As a non-invasive imaging method, the high-frame-rate vector flow imaging technique showed potential value in the preoperative assessment of the symptomatic carotid atherosclerotic stenosis and diagnosing carotid atherosclerotic stenosis in aging patients.

Mass Spectrometry Imaging as a Tool to Investigate Region Specific Lipid Alterations in Symptomatic Human Carotid Atherosclerotic Plaques.

Atherosclerosis is characterized by fatty plaques in large and medium sized arteries. Their rupture can causes thrombi, occlusions of downstream vessels and adverse clinical events. The investigation of atherosclerotic plaques is made difficult by their highly heterogeneous nature. Here we propose a spatially resolved approach based on matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging to investigate lipids in specific regions of atherosclerotic plaques. The method was applied to a small dataset including symptomatic and asymptomatic human carotid atherosclerosis plaques. Tissue sections of symptomatic and asymptomatic human carotid atherosclerotic plaques were analyzed by MALDI mass spectrometry imaging (MALDI MSI) of lipids, and adjacent sections analyzed by histology and immunofluorescence. These multimodal datasets were used to compare the lipid profiles of specific histopathological regions within the plaque. The lipid profiles of macrophage-rich regions and intimal vascular smooth muscle cells exhibited the largest changes associated with plaque outcome. Macrophage-rich regions from symptomatic lesions were found to be enriched in sphingomyelins, and intimal vascular smooth muscle cells of symptomatic plaques were enriched in cholesterol and cholesteryl esters. The proposed method enabled the MALDI MSI analysis of specific regions of the atherosclerotic lesion, confirming MALDI MSI as a promising tool for the investigation of histologically heterogeneous atherosclerotic plaques.

Abstract 15301: Peripheral CD56 bright Natural Killer Cells Associate With Increased Atheroburden and Unstable Plaque Features in Humans

Background: Atherosclerotic plaques in mice and humans contain natural killer (NK) cells. Data on the role of NK cells in atherosclerosis using different transgenic mice models is inconsistent. Some studies showed that NK cells augment atherosclerosis through their cytotoxic potential, while others reported no effect. Evidence in humans indicates that NK cells are atherogenic. Frequency of NK cells and expression of the activating NK cell receptors are associated with severe disease and symptomatic carotid atherosclerotic plaques in humans. Hypothesis: We tested if coronary artery disease (CAD) subjects with necrotic plaques have a higher frequency of the circulating NK cells. Methods: We performed mass cytometry on peripheral blood mononuclear cells from matched CAD subjects with low and high (n=9 each) necrotic plaque content as determined by intravascular ultrasound-virtual histology. Results: CAD subjects with high necrotic plaques have significantly higher atheroburden, stenosis, calcium, fatty plaque content, and lower plaque fibrosis. Interestingly, CAD subjects with high necrotic plaques exhibited a significantly higher frequency of the CD56 bright NK cells as compared to those with low necrotic plaques (4.618 ± 0.625 vs 2.481 ± 0.37; p=0.011). Moreover, frequency of CD25 + NK cells also trended to be higher in subjects with high necrotic plaques. The frequency of the cytotoxic CD56 dim NK cells did not differ between the two groups. Correlation analyses demonstrated a significant positive association of CD56 bright NK cells with atheroburden (r=0.43; p=0.04), stenosis (r=0.58; p=0.005), plaque necrotic (r=0.71; p=0.002), calcium contents (r=0.73; p=0.0001), and a negative association with the plaque fibrous content (r=0.71; p= 0.0003). CD25 + NK cells also showed similar trending associations with burden, stenosis and plaque features. Conclusions: Our data provides yet another evidence of the atherogenic role of NK cells in humans and indicates that the CD56 bright NK cells may contribute to the development of a vulnerable plaque. CD56 bright NK cells produce proinflammatory cytokines including IFN-γ and TNF-α and cytotoxic enzymes that may contribute to increased inflammation, cell activation, and apoptosis within the plaque.

Factor VII Activating Protease Expression in Human Platelets and Accumulation in Symptomatic Carotid Plaque.

BackgroundFactor VII activating protease (FSAP) is of interest as a marker for vascular inflammation and plaque destabilization. The aim of this study was to analyze the expression profile of FSAP in endarterectomy specimens that were taken from patients with asymptomatic and symptomatic carotid atherosclerotic plaques and to compare them with circulating FSAP levels.Methods and ResultsPlasma FSAP concentration, activity, and mRNA expression were measured in endarterectomy specimens and in monocytes and platelets. Plaque and plasma FSAP levels were higher in symptomatic patients (n=10) than in asymptomatic patients (n=14). Stronger FSAP immunostaining was observed in advanced symptomatic lesions, in intraplaque hemorrhage‐related structures, and in lipid‐rich areas within the necrotic core. FSAP was also colocalized with monocytes and macrophages (CD11b/CD68‐positive cells) and platelets (CD41‐positive cells) of the plaques. Moreover, human platelets expressed FSAP in vitro, at both the mRNA and protein levels. Expression is stimulated by thrombin receptor‐activating peptide and ADP and reduced by acetylsalicylic acid.ConclusionsPlasma FSAP levels were significantly increased in patients with symptomatic carotid stenosis and thus may be involved in plaque development This plaque‐associated FSAP may be produced by platelets or macrophages or may be taken up from the circulation. To establish FSAP’s utility as a circulating or plaque biomarker in patients with symptomatic carotid atherosclerotic plaques, further studies are needed.

Comparison of the Values of MRI in the Differential Diagnosis of Symptomatic Carotid Stenosis and Atherosclerotic Plaque

Objective: To evaluate the values of Carotid Magnetic Resonance Imaging (MRI) in the differential diagnosis of symptomatic carotid stenosis and atherosclerotic plaque. Methods: 56 patients with ischemic cerebrovascular disease admitted in our hospital from October 2018 to October 2019 were selected and treated with Carotid MRI and digital subtraction angiography (DSA) examinations. According to the two examination results recorded and the “gold standard” of DSA examination, values of Carotid MRI in the differential diagnosis of symptomatic carotid stenosis were evaluated. Results: According to the “gold standard” of DSA examination, the sensitivity and specificity of MRI examination for carotid stenosis were: Mild: 92.54% and 97.78%; Moderate: 85.71% and 88.78%; Severe: 100.00% and 97.8%; and complete occlusion: 100.00% and 100.00%; The proportions of intraplaque haemorrhage and ruptured fibrous cap in different degrees of carotid artery stenosis were: Mild: 30.16% and 22.22%; Moderate: 43.48% and 39.13%; And severe: 57.89% and 52.63%. Conclusion: MRI examination can evaluate the degree of symptomatic carotid artery stenosis, and show the characteristics of atherosclerotic plaque at the same time to provide a reference for early clinical differential diagnosis and treatment.

Symptomatic Carotid Atherosclerotic Plaques Are Associated With Increased Infiltration of Natural Killer (NK) Cells and Higher Serum Levels of NK Activating Receptor Ligands.

A wide array of immune cells, including lymphocytes, is known to be present and to play a pathogenetic role in atherosclerotic lesions. However, limited information is currently available regarding the presence of Natural Killer (NK) cell subsets within vessel plaque, and more in general, regarding their role in human atherosclerosis. We evaluated the distribution of NK cells in human carotid atherosclerotic plaques, dissecting asymptomatic and symptomatic patients (identified as affected by stroke, transient ischemic attack, or amaurosis fugax within 6 months) with the aim of shedding light on the putative contribution of NK cells to the pathogenic process that leads to plaque instability and subsequent clinical complications. We observed that carotid plaques were consistently infiltrated by NK cells and, among them, CD56brightperforinlow NK cells were abundantly present and displayed different markers of tissue residency (i.e., CD103 CD69 and CD49a). Interestingly, carotid atherosclerotic plaques of symptomatic patients showed a higher content of NK cells and an increased ratio between CD56brightperforinlow NK cells and their CD56dimperforinhigh counterpart. NK cells isolated from plaques of symptomatic patients were also stronger producers of IFN-γ. Analysis of the expression of NK activating receptor ligands (including MICA/B, ULBP-3, and B7-H6) in atherosclerotic carotid plaques revealed that they were abundantly expressed by a HLA-DR+CD11c+ myeloid cell population resident in the plaques. Remarkably, sera of symptomatic patients contained significant higher levels of soluble ligands for NK activating receptors. Our observations indicate that CD56bright NK cells accumulate within human atherosclerotic lesions and suggest a possible contribution of NK cells to the process determining plaque instability.

Abstract 226: Statin Therapy is Associated With Decreased Neovascularization in Symptomatic Carotid Atherosclerotic Plaque: A Pathological Analysis

Background: Statin treatment has been shown to be associated with decreased intraplaque neovascularization in human carotid arteries by various imaging modalities or in animal models by pathological analysis. However, whether statin treatment attenuates intraplaque neovascularization in human carotid plaque has not been fully described. The aim of this study was to analyze the possible relationships between statin treatment and intraplaque microvessels (MVs) in patients undergoing carotid endarterectomy (CEA). Methods: Among consecutive 79 patients with advanced carotid artery stenosis (&gt;70%) between May 2015 and February 2017, 66 patients without statin therapy (group 1) and 13 patients with statin therapy (group 2) were analyzed. The specimens were stained with hematoxylin/eosin and elastica-Masson. Immunohistochemistry was performed, using an endothelial specific antibody to CD31, CD34 and PDGFRβ. The number of intraplaque MVs was analyzed in each specimen. MV density was defined as number of MVs per mm 2 . Results: The mean number of MVs was fewer in group 2 when compared with that in group 1 (25.8±17.6 vs. 50.8±31.8 /section, P&lt;0.001). The mean MV density was lower in group 2 when compared with that in group 1 (1.06±0.84 vs. 2.19±1.43 /mm 2 , P&lt;0.001). There was no significant difference in the mean concentration of low-density lipoprotein cholesterol between group 1 and group 2 (121±32 mg/dl vs. 105±37 mg/dl, P=0.118). Conclusions: This pathological analysis of carotid atherosclerotic plaque suggests that statin therapy is associated with decreased intraplaque neovascularization in symptomatic patients undergoing CEA. This plaque stability might be derived from pleiotropic effect beyond lipid lowering of statin therapy.

No Association between Thrombin Generation and Intra-Plaque Haemorrhage in Symptomatic Carotid Atherosclerotic Plaques: The Plaque at RISK (PARISK) Study.

Carotid atherosclerosis is an important cause of stroke. Intra-plaque haemorrhage (IPH) on magnetic resonance imaging (MRI) increases stroke risk. Development of IPH is only partly understood. Thrombin is an essential enzyme in haemostasis. Experimental animal studies have shown conflicting results on the relation between thrombin and plaque vulnerability. We hypothesize that decreased thrombin generation (TG) is associated with IPH and plaque vulnerability. This article investigates whether TG is associated with IPH and other features of plaque vulnerability in stroke patients. Recently symptomatic stroke patients underwent carotid MRI and blood sampling. MRI plaque features include plaque burden, presence of IPH, amount of lipid-rich necrotic core (LRNC), calcified tissue and fibrous tissue (% of total wall volume). TG was assessed in platelet-poor plasma and expressed as: peak height (PH) and endogenous thrombin potential (ETP). MR images could be analysed in 224 patients. Blood samples were available in 161 of 224 patients. Binary multivariate logistic and linear regression were used to investigate the association between TG and MRI plaque features. IPH and LRNC were present in 65 (40%) and 102 (63%) of plaques. There were no significant associations between TG and IPH; PH odds ratio (OR) = 1, 95% confidence interval (CI): 0.76 to 1.45 and ETP OR = 1, 95% CI: 0.73 to 1.37. After correction for age, sex and hypercholesterolaemia, the association was weak but non-significant; PH: OR = 0.76, 95% CI: 0.52 to 1.10 and ETP: OR = 0.73, 95% CI: 0.53 to 1.37. Features of carotid plaque on MRI show no significant association with TG in stroke patients. Systemic TG does not seem to be an important factor in IPH development.

Assessment of Carotid Artery Plaque Components With Machine Learning Classification Using Homodyned-K Parametric Maps and Elastograms

Quantitative ultrasound (QUS) imaging methods, including elastography, echogenicity analysis, and speckle statistical modeling, are available from a single ultrasound (US) radio-frequency data acquisition. Since these US imaging methods provide complementary quantitative tissue information, characterization of carotid artery plaques may gain from their combination. Sixty-six patients with symptomatic ( n = 26 ) and asymptomatic ( n = 40 ) carotid atherosclerotic plaques were included in the study. Of these, 31 underwent magnetic resonance imaging (MRI) to characterize plaque vulnerability and quantify plaque components. US radio-frequency data sequence acquisitions were performed on all patients and were used to compute noninvasive vascular US elastography and other QUS features. Additional QUS features were computed from three types of images: homodyned-K (HK) parametric maps, Nakagami parametric maps, and log-compressed B-mode images. The following six classification tasks were performed: detection of 1) a small area of lipid; 2) a large area of lipid; 3) a large area of calcification; 4) the presence of a ruptured fibrous cap; 5) differentiation of MRI-based classification of nonvulnerable carotid plaques from neovascularized or vulnerable ones; and 6) confirmation of symptomatic versus asymptomatic patients. Feature selection was first applied to reduce the number of QUS parameters to a maximum of three per classification task. A random forest machine learning algorithm was then used to perform classifications. Areas under receiver-operating curves (AUCs) were computed with a bootstrap method. For all tasks, statistically significant higher AUCs were achieved with features based on elastography, HK parametric maps, and B-mode gray levels, when compared to elastography alone or other QUS alone ( ). For detection of a large area of lipid, the combination yielding the highest AUC (0.90, 95% CI 0.80-0.92, ) was based on elastography, HK, and B-mode gray-level features. To detect a large area of calcification, the highest AUC (0.95, 95% CI 0.94-0.96, ) was based on HK and B-mode gray level features. For other tasks, AUCs varied between 0.79 and 0.97. None of the best combinations contained Nakagami features. This study shows the added value of combining different features computed from a single US acquisition with machine learning to characterize carotid artery plaques.

Stabilization of symptomatic carotid atherosclerotic plaques by statins: a clinico-pathological analysis

Human and animal studies have revealed a stabilization of atherosclerotic plaques by statins. However, the stabilization of human carotid plaques has not been thoroughly described pathologically. This analysis explored the relationship between statin therapy and plaque stability in carotid endarterectomy (CEA) specimens. We analyzed specimens harvested between May 2015 and February 2017, from 79 consecutive patients presenting with > 70% carotid artery stenoses, of whom 66 were untreated (group 1) and 13 treated (group 2) with a statin. Immunohistochemistry was performed, using an endothelial specific antibody to CD31, CD34 and platelet derived growth factor receptor-β. The prevalence of plaque ruptures (P = 0.009), lumen thrombi (P = 0.009), inflammatory cells (P = 0.008), intraplaque hemorrhages (P = 0.030) and intraplaque microvessels (P < 0.001) was significantly lower in group 2 than in group 1. Among 66 patients presenting with strokes and infarct sizes > 1.0 cm3 on magnetic resonance imaging, the mean infarct volume was significantly smaller (P = 0.031) in group 2 (4.2 ± 2.5 cm3) than in group 1 (8.2 ± 7.1 cm3). The difference in mean concentration of low-density lipoprotein cholesterol between group 1 (121 ± 32 mg/dl) and group 2 (105 ± 37 mg/dl) was non-significant (P = 0.118). This analysis of plaques harvested from patients undergoing CEA suggests that statin therapy mitigates the plaque instability, which, in patients presenting with strokes, might decrease infarct volume.

Abstract 338: Statin Therapy is Associated with Decreased Plaque Instability in Symptomatic Carotid Atherosclerotic Plaque: a Clinicopathological Analysis

Background: Statin therapy has been shown to deplete atherosclerotic plaque instability in human carotid arteries by various imaging modalities or in animal models by pathological analysis. However, whether statin therapy attenuates plaque instability in human carotid plaque has not been fully described in a pathological analysis. The aim of this study was to analyze pathologically the possible relationships between statin therapy and plaque stability in patients undergoing carotid endarterectomy (CEA). Methods: Among consecutive 79 patients with advanced carotid artery stenosis (&gt;70%) between May 2015 and February 2017, 66 patients without statin therapy (group 1) and 13 patients with statin therapy (group 2) were analyzed. The specimens were stained with hematoxylin/eosin and elastica-Masson. Immunohistochemistry was performed, using an endothelial specific antibody to CD31, CD34 and PDGFRβ. Results: Plaques from group 2 had significantly less plaque rupture (P=0.009), lumen thrombus (P=0.009), inflammatory cells (P=0.008), intraplaque hemorrhage (P=0.030) and intraplaque microvessels (P&lt;0.001), compared with those from group 1. Among stroke patients with infarct size &gt;1.0 cm 3 in MRI, the mean infarct volume in group 2 (4.2 ± 2.5 cm 3 ) was significantly smaller than that in group 1 (8.2 ± 7.1 cm 3 , p = 0.031). There was no significant difference in the mean concentration of low-density lipoprotein cholesterol between group 1 and group 2 (121 ± 32 mg/dl vs. 105 ± 37 mg/dl, P=0.118). Conclusions: This clinicopathological analysis of carotid atherosclerotic plaque suggests that statin therapy is associated with decreased plaque instability, which might result in smaller infarct volume in stroke patients undergoing CEA. This plaque stability might be derived from pleiotropic effect beyond lipid lowering of statin therapy.

The Nature of Iron Deposits Differs between Symptomatic and Asymptomatic Carotid Atherosclerotic Plaques.

Iron within atherosclerotic plaque has been implicated as a catalyst of oxidative stress that causes progression of plaque, and plaque rupture. Iron is believed to accumulate within plaque by incorporation of erythrocytes following plaque rupture and hemorrhage. There is only indirect evidence to support this hypothesis. Plaque specimens were obtained from ten symptomatic and fifteen asymptomatic patients undergoing carotid endarterectomy at a single institution. Plaques were sectioned for study using synchrotron radiation induced X-ray fluorescence the study the distribution of zinc, calcium and iron. Histologic staining was carried out with Prussian Blue, and immunohistochemical staining was done to localize macrophages with CD68. Data were compared against patient clinical variables. Ten symptomatic (15 ± 10 days between index symptoms and surgery) and fifteen asymptomatic carotid plaques were studied. Zinc and calcium co-localized in mineralized areas of symptomatic and asymptomatic plaque. Iron was identified away from zinc and calcium in both symptomatic and asymptomatic plaques. Within the symptomatic plaques, iron was found within the thrombus associated with plaque rupture and hemorrhage. It did not stain with Prussian Blue, but was found in association with CD68 positive macrophages. In symptomatic plaques, the abundance of iron showed an association with the source patient’s LDL cholesterol (R2 = 0.39, Significance F = 0.05). Iron in asymptomatic plaque was present as hemosiderin/ferritin that stained positive with Prussian Blue, and was observed in association with CD68 positive macrophages. Iron in acutely symptomatic plaques is found within thrombus, in the presence of macrophages. The abundance of iron in symptomatic plaques is associated with the source patient’s LDL cholesterol. Within asymptomatic plaques, iron is found in association with macrophages, as hemosiderin/ferritin.

Vascular Endothelial Growth Factor and Monocyte Chemoattractant Protein-1 Levels Unaltered in Symptomatic Atherosclerotic Carotid Plaque Patients from North India

We aimed to identify the role of vascular endothelial growth factor (VEGF) and monocyte chemoattractant protein (MCP-1) as a serum biomarker of symptomatic carotid atherosclerotic plaque in North Indian population. Individuals with symptomatic carotid atherosclerotic plaque have high risk of ischemic stroke. Previous studies from western countries have shown an association between VEGF and MCP-1 levels and the incidence of ischemic stroke. In this study, venous blood from 110 human subjects was collected, 57 blood samples of which were obtained from patients with carotid plaques, 38 neurological controls without carotid plaques, and another 15 healthy controls who had no history of serious illness. Serum VEGF and MCP-1 levels were measured using commercially available enzyme-linked immunosorbent assay. We also correlated the data clinically and carried out risk factor analysis based on the detailed questionnaire obtained from each patient. For risk factor analysis, a total of 70 symptomatic carotid plaque cases and equal number of age and sex matched healthy controls were analyzed. We found that serum VEGF levels in carotid plaque patients did not show any significant change when compared to either of the controls. Similarly, there was no significant upregulation of MCP-1 in the serum of these patients. The risk factor analysis revealed that hypertension, diabetes, and physical inactivity were the main correlates of carotid atherosclerosis (p < 0.05). Prevalence of patients was higher residing in urban areas as compared to rural region. We also found that patients coming from mountain region were relatively less vulnerable to cerebral atherosclerosis as compared to the ones residing at non mountain region. On the contrary, smoking, obesity, dyslipidemia, alcohol consumption, and tobacco chewing were not observed as the determinants of carotid atherosclerosis risk in North India (p > 0.05). We conclude that the pathogenesis of carotid plaques may progress independent of these inflammatory molecules. In parallel, risk factor analysis indicates hypertension, diabetes, and sedentary lifestyle as the most significant risk factors of ischemic stroke identified in North India. This could be helpful in early identification of subjects at risk for stroke and devising health care strategies.

TCT-195 Novel Quantitative Virtual Histology Parameters in the Asymptomatic and Symptomatic Carotid Atherosclerotic Plaque Imaging: Data from the First 222 Patients in CRACK-VH Study

TCT-195 Novel Quantitative Virtual Histology Parameters in the Asymptomatic and Symptomatic Carotid Atherosclerotic Plaque Imaging: Data from the First 222 Patients in CRACK-VH Study

Increased vascularization of shoulder regions of carotid atherosclerotic plaques from patients with diabetes

Increased vascularization is considered an important contributing factor for plaque vulnerability. Microvascular proliferative disease in patients with diabetes results in renal damage and visual loss. We assessed the hypothesis that vascularization in carotid atherosclerotic tissue is increased in diabetic patients, especially in the critical shoulder regions of the plaque. Carotid endarterectomy specimens, clinical data, and blood samples were collected from patients with symptomatic carotid artery stenosis (median 85 days after clinical event) and pharmacologic treatment for diabetes (n = 26) or no diabetes (n = 85). Plaques were fixed in formalin and transverse tissue sections prepared. Histopathology and immunohistochemistry were performed for detection of endothelial cells (anti-CD34), macrophages (anti-CD68), vascular endothelial growth factor (VEGF), and its receptor (VEGFR-2). Neovascularization was assessed as CD34(+) neovessel density in the entire section area and by the presence or absence of CD34(+) vessels in the shoulder and cap regions of the plaques. The patient groups did not differ significantly in neovascularization in the entire transverse sections (2.0 vs 2.1 vessels/mm(2); P = .61) or in the fibrous cap (52% of the patients in both groups; P = .95). Neovascularization of the plaque shoulder regions was observed in 52% of the diabetic patients and in 26% of the nondiabetic patients (P = .028). VEGF-stained areas were similar in the two patient groups (0.4% and 0.2% of shoulder area; P = .61). Patients with diabetes had more VEGFR-2 (1.0% vs 0.2% of shoulder area; P < .016) and less CD68 staining (0.4% vs 3.6% of shoulder area; P < .008). Time from clinical event to surgery was positively associated with neovascularization of the plaque shoulder regions (≤90 days, 18% of patients; >90 days, 50% of patients; P = .002), independently of diabetes status. Diabetes was associated with increased vascularization of the shoulder regions in patients with symptomatic carotid atherosclerotic plaques. This was accompanied by increased expression of VEGFR-2. The increased vascularization of the plaque shoulder regions may help explain why patients with diabetes are at increased risk of atherosclerotic complications.