Symptomatic Plaques Research Articles

VALIDATION OF [18F]-SODIUM FLUORIDE AS A MARKER OF ACTIVE CALCIFICATION AND HIGH-RISK CAROTID PLAQUE: A SUB-STUDY OF THE CANADIAN ATHEROSCLEROSIS IMAGING NETWORK (CAIN-2)

[18F]-sodium fluoride (NaF) positron emission tomography (PET) uptake may serve as an imaging-derived biomarker of active calcification. It is postulated that NaF binds to hydroxyapatite molecules that are expressed in regions with active calcification. We aimed to: 1. Validate NaF uptake imaged with PET/CT, as a direct marker of active calcification within carotid plaque, as determined by its association with intraplaque expression of hydroxyapatite; and 2. Determine whether NaF uptake is related to cerebrovascular events. Eleven patients (69 ± 5 years, 3 females) scheduled for carotid endarterectomy were prospectively recruited. Patients underwent NaF PET and contrast-enhanced CTA imaging of carotid vasculature. The bifurcation of the common carotid was used as a reference point; maximum NaF uptake normalized to blood (tissue to blood ratio - TBR) was measured at every PET slice extending 2 cm above and below the bifurcation. Following endarterectomy, excised carotid plaque was fixed, sectioned and stained with Goldner’s Trichrome (marker of hydroxyapatite expression). An electronic algorithm was applied to quantify hydroxyapatite expression on whole-slide digitized images. Using the distance from the bifurcation, pathology was aligned with CTA and co-registered with PET. To determine the relationship between NaF uptake and cerebrovascular events, bilateral carotid plaque was classified as either symptomatic (associated with cerebrovascular events) or clinically silent, asymptomatic plaque. Carotid endarterectomy was performed in 11 patients; one patient received a 2nd carotid endarterectomy due to bilateral disease. Two patients were excluded (intolerance to CT contrast agent and PET/CT misalignment). Staining was available for 8 excised plaques. NaF uptake was related to intraplaque hydroxyapatite expression (r=0.45, p<0.001) (Figure 1). NaF uptake was greater at the side of carotid endarterectomy (endarterectomy: 3.73±1.1 TBR vs. contralateral: 2.82±0.6 TBR, p=0.030). Symptomatic carotid plaque had evidence for greater NaF uptake (symptomatic plaque: 3.75±1.1 TBR vs. asymptomatic plaque: 2.79±0.6 TBR p=0.04) NaF uptake imaged with PET/CT is related to intraplaque expression of hydroxyapatite, which is expressed in regions with active calcific activity. NaF uptake was greater in plaque that was scheduled for endarterectomy, as well as symptomatic plaque associated with cerebrovascular events. NaF PET/CT may serve as a novel biomarker of active calcification and enable identification of high-risk patients. Larger outcome based follow-up studies are underway.

Characterization of intracranial atherosclerotic stenosis using high-resolution MRI study--rationale and design.

Intracranial atherosclerosis is a leading cause of stroke, but little is known about the composition of the intracranial atherosclerotic lesion and how intracranial plaque morphology is related to the risk of stroke. High-resolution magnetic resonance imaging (HR MRI) has been used in patients with extracranial carotid atherosclerosis as an invivo tool to identify, with high-interrater agreement, histologically defined plaque components (i.e., intraplaque hemorrhage, fibrous cap, and lipid core), which have been shown to be predictors of recurrent stroke. With careful imaging the components ofatherosclerotic plaque can be visualized in the intracranial arteries using HRMRI, but there are no reports of reproducibility or interrater reliability. The Characterization of intracranial atherosclerotic stenosis using high-resolution MRI (CHIASM) study is a single-center NIH-funded prospective observational study, to (1) demonstrate high -interrater agreement for identifying intracranial plaque components on HR MRI, (2) determine the frequency of these components in symptomatic versus asymptomatic plaques, and (3) estimate the 1-year rate of stroke in the territory of high-risk plaque components. CHIASM will recruit 90 patients with 50-99% intracranial atherosclerosis to undergo HRMRI of the intracranial artery plaque at enrollment and 1-year follow-up. Both symptomatic and asymptomatic subjects will be recruited. Determination of good interrater reliability is an important first step in the development of HR MRI as a tool to predict risk in patients with intracranial atherosclerosis. This study will inform the design of future multicenter studies to determine the prevalence and prognosis of intracranial atherosclerotic plaque components. Such studies could lead to new understanding of the pathophysiological mechanisms of cerebral ischemia in patients with atherosclerotic intracranial stenosis, improvements in risk stratification, and potentially to new treatments of this common and serious disease.

In silico analyses of metagenomes from human atherosclerotic plaque samples.

BackgroundThrough several observational and mechanistic studies, microbial infection is known to promote cardiovascular disease. Direct infection of the vessel wall, along with the cardiovascular risk factors, is hypothesized to play a key role in the atherogenesis by promoting an inflammatory response leading to endothelial dysfunction and generating a proatherogenic and prothrombotic environment ultimately leading to clinical manifestations of cardiovascular disease, e.g., acute myocardial infarction or stroke. There are many reports of microbial DNA isolation and even a few studies of viable microbes isolated from human atherosclerotic vessels. However, high-resolution investigation of microbial infectious agents from human vessels that may contribute to atherosclerosis is very limited. In spite of the progress in recent sequencing technologies, analyzing host-associated metagenomes remain a challenge.ResultsTo investigate microbiome diversity within human atherosclerotic tissue samples, we employed high-throughput metagenomic analysis on: (1) atherosclerotic plaques obtained from a group of patients who underwent endarterectomy due to recent transient cerebral ischemia or stroke. (2) Presumed stabile atherosclerotic plaques obtained from autopsy from a control group of patients who all died from causes not related to cardiovascular disease. Our data provides evidence that suggest a wide range of microbial agents in atherosclerotic plaques, and an intriguing new observation that shows these microbiota displayed differences between symptomatic and asymptomatic plaques as judged from the taxonomic profiles in these two groups of patients. Additionally, functional annotations reveal significant differences in basic metabolic and disease pathway signatures between these groups.ConclusionsWe demonstrate the feasibility of novel high-resolution techniques aimed at identification and characterization of microbial genomes in human atherosclerotic tissue samples. Our analysis suggests that distinct groups of microbial agents might play different roles during the development of atherosclerotic plaques. These findings may serve as a reference point for future studies in this area of research.Electronic supplementary materialThe online version of this article (doi:10.1186/s40168-015-0100-y) contains supplementary material, which is available to authorized users.

Ultrasound Characteristics of Symptomatic Carotid Plaques: A Systematic Review and Meta-Analysis

Background: Ultrasound is the most commonly used imaging modality for assessing carotid artery stenosis. A number of studies have demonstrated that surface irregularities, heterogeneous echotexture and hypoechoic plaques are risk factors for acute ischemic stroke. We performed a systematic review and meta-analysis of the literature to better define the risk of stroke based on the sonographic characteristics of carotid plaques. Materials and Methods: We performed a comprehensive search for studies reporting imaging findings of symptomatic and asymptomatic carotid plaques on ultrasound using MEDLINE and EMBASE. We included both case-control and cohort studies examining the relationship between complex plaque and acute ischemic stroke or transient ischemic attack. Complex plaque was defined as plaque that had any of the following characteristics: heterogeneous echogenicity, echolucency, neovascularization, surface irregularity, ulceration, and intraplaque motion. Meta-analyses using the random-effects model were performed for complex plaque and each of the individual complex plaque characteristics. p < 0.05 was considered statistically significant. We explored the impact of publication bias by constructing funnel plots and testing their symmetry. We conducted the meta-analysis using Comprehensive Meta-analysis version 2.2, Englewood, N.J., USA. Results: A total of 1,013 articles were screened and 23 studies with 6,706 carotid plaques were included. Ultrasound plaque characteristics with a higher prevalence in individuals with symptomatic compared to asymptomatic carotid artery stenosis included plaque neovascularity (OR = 19.68, 95% CI = 3.14-123.16), complex plaque (OR = 5.12, 95% CI = 3.42-7.67), plaque ulceration (OR = 3.58, 95% CI = 1.66-7.71), plaque echolucency (OR = 3.99, 95% CI = 3.06-5.19) and intraplaque motion (OR = 1.57, 95% CI = 1.02-2.41). Variables not associated with symptom status included heterogenous echotexture (OR = 2.68, 95% CI = 0.56-12.80) and surface irregularity without ulceration (OR = 2.38, 95% CI = 0.70-8.11). No evidence of publication bias was observed based on Eggers test (p value of 0.05 for complex plaque and 0.53 for plaque echolucency). The remaining plaque features had insufficient data to assess for publication bias. Conclusions: Our meta-analysis and systematic review of the literature demonstrated that plaques with complex features, particularly those with echolucency, neovascularization, ulceration and intraplaque motion are associated with ischemic symptoms. Assessment of carotid plaque on ultrasound may provide stroke risk information beyond measurement of luminal stenosis. Thus, sonographic evaluation of carotid artery stenosis should focus on the detection of these plaque characteristics in addition to quantifying the degree of stenosis.

Blockade of Ets-1 attenuates epidermal growth factor-dependent collagen loss in human carotid plaque smooth muscle cells.

Although degradation of extracellular matrix by matrix metalloproteinases (MMPs) is thought to be involved in symptomatic (S) carotid plaques in atherosclerosis, the mechanisms of MMP expression are poorly understood. Here, we demonstrate that collagen loss in vascular smooth vessel cells (VSMCs) isolated from S plaques was induced by epidermal growth factor (EGF) through the activation of p38-MAPK and JNK-MAPK pathways. Inhibitors of p38-MAPK and JNK-MAPK signaling pathways downregulated the expression of MMP-1 and MMP-9. In addition, we examined whether v-ets erythroblastosis virus E26 oncogene homologue 1 (Ets-1), an important regulator of different genes, is involved in destabilizing S plaques in patients with carotid stenosis. We demonstrate that EGF induces Ets-1 expression and decreases interstitial and basement membrane collagen in vascular smooth muscle cells (VSMCs) from patients with carotid stenosis. Increased expression of MMP-1 and -9 and decreased collagen mRNA transcripts were also found in Ets-1-overexpressed VSMCs. Transfection with both dominant-negative form of Ets-1 and small interfering RNA blocked EGF-induced MMP-1 and -9 expressions and increased the mRNA transcripts for collagen I (α1) and collagen III (α1) in S compared with asymptomatic (AS) carotid plaques. Inhibitors of p38-MAPK (SB202190) and JNK-MAPK (SP600125) signaling pathways decreased the expression of Ets-1, MMP-1, and MMP-9 and increased collagen type I and III expression in EGF-treated VSMCs. This study provides a mechanistic insight into the role of Ets-1 in the plaque destabilization in patients with carotid stenosis involving p38-MAPK and JNK signaling pathways.

Prediction of the time period of stroke based on ultrasound image analysis of initially asymptomatic carotid plaques.

Non-invasive ultrasound imaging of carotid plaques can provide information on the characteristics of the arterial wall including the size, morphology and texture of the atherosclerotic plaques. Several studies were carried out that demonstrated the usefulness of these feature sets for differentiating between asymptomatic and symptomatic plaques and their corresponding cerebrovascular risk stratification. The aim of this study was to develop predictive modelling for estimating the time period of a stroke event by determining the risk for short term (less or equal to three years) or long term (more than three years) events. Data from 108 patients that had a stroke event have been used. The information collected included clinical and ultrasound imaging data. The prediction was performed at base line where patients were still asymptomatic. Several image texture analysis and clinical features were used in order to create a classification model. The different features were statistically analyzed and we conclude that image texture analysis features extracted using Spatial Gray Level Dependencies method had the best statistical significance. Several predictive models were derived based on Binary Logistic Regression (BLR) and Support Vector Machines (SVM) modelling. The best results were obtained with the SVM modelling models with an average correct classifications score of 77±7% for differentiating between stroke event occurrences within 3 years versus more than 3 years. Further work is needed in investigating additional multiscale texture analysis features as well as more modelling techniques on more subjects.

MicroRNA deregulation in symptomatic carotid plaque

Embolization of carotid stenotic plaques is the direct cause of stroke in nearly 20% of cases. Genetic mechanisms and especially the roles played by microRNAs in the regulation of plaque destabilization and rupture are mostly unknown. The aim of this pilot study was to compare the expression of seven microRNAs allegedly involved in plaque growth and instability (miR-100, 125a, 127, 133a, 145, 155, and 221), between symptomatic and asymptomatic human carotid plaques. Thirty patients undergoing carotid endarterectomy in our department were prospectively included. Carotid plaques were subdivided into symptomatic (n= 15) and asymptomatic (n= 15) according to the presence or absence of stroke. After isolation of total RNA from atherosclerotic plaques, microRNAs were quantified by real-time polymerase chain reaction. The two groups of patients were comparable in terms of age, gender, risk factors for cerebral ischemia, medication, and stenosis severity. All seven microRNAs were quantified in extracted carotid plaques. miR-100, miR-125a, miR-127, miR-133a, miR-145, and miR-221 were significantly overexpressed in symptomatic vs asymptomatic plaques. miR-125a expression was significantly inversely correlated with the circulating level of low-density lipoprotein cholesterol in the symptomatic group. This pilot study evaluated the expression of seven selected miRNAs in human carotid plaques from a small group of patients and suggested a potential regulatory role for these miRNAs in evolution of the plaque towards growth, instability and rupture. Studies based on larger sample sizes are required to determine the potential use of miR-100, miR-125a, miR-127, miR-133a, miR-145, and miR-221 as biomarkers or therapeutic targets for stroke.

Investigating the Effect of a Single Infusion of Reconstituted High-Density Lipoprotein in Patients with Symptomatic Carotid Plaques

BackgroundElevation of plasma high-density lipoprotein (HDL) cholesterol concentration reduces cardiovascular mortality and morbidity. HDLs have been shown to possess acute anti-inflammatory, antioxidant, and antithrombotic properties. We hypothesize that HDL therapy can acutely alter local and systemic manifestations of plaque instability.MethodsForty patients with early symptomatic carotid disease were randomized to either receive reconstituted HDL (rHDL) 40 mg/kg (n = 20) or placebo (n = 20). Carotid endarterectomies were performed 24 hr later. Plaques were obtained intraoperatively and used for measurement of thrombomodulatory genes expression. Plasma samples were collected before the infusion, 24 and 48 hr later to measure changes in systemic markers of plaque instability.ResultsNo significant differences were noted in thrombomodulatory genes expression between the 2 groups. Systemic levels of tissue factor, matrix metalloproteinase 9 (MMP-9), and monocyte chemotactic factor-1 (MCP-1) were significantly reduced in the rHDL group. However, the effects on MMP-9 and MCP-1 were abolished in the immediate postoperative period. Although rHDL did not affect plasma interleukin-6 levels 24 hr following the infusion, it prevented the significant postoperative elevation seen in the placebo group.ConclusionsA single infusion of rHDL can acutely alter plasma biomarkers associated with plaque instability and cardiovascular morbidity.

64 Cu-DOTATATE PET/MRI for Detection of Activated Macrophages in Carotid Atherosclerotic Plaques

Objective— A feature of vulnerable atherosclerotic plaques of the carotid artery is high activity and abundance of lesion macrophages. There is consensus that this is of importance for plaque vulnerability, which may lead to clinical events, such as stroke and transient ischemic attack. We used positron emission tomography (PET) and the novel PET ligand [ 64 Cu] [1,4,7,10-tetraazacyclododecane- N , N ′, N ″, N ‴-tetraacetic acid]- d -Phe1,Tyr3-octreotate ( 64 Cu-DOTATATE) to specifically target macrophages via the somatostatin receptor subtype-2 in vivo. Approach and Results— Ten patients underwent simultaneous PET/MRI to measure 64 Cu-DOTATATE uptake in carotid artery plaques before carotid endarterectomy. 64 Cu-DOTATATE uptake was significantly higher in symptomatic plaque versus the contralateral carotid artery ( P &lt;0.001). Subsequently, a total of 62 plaque segments were assessed for gene expression of selected markers of plaque vulnerability using real-time quantitative polymerase chain reaction. These results were compared with in vivo 64 Cu-DOTATATE uptake calculated as the mean standardized uptake value. Univariate analysis of real-time quantitative polymerase chain reaction and PET showed that cluster of differentiation 163 (CD163) and CD68 gene expression correlated significantly but weakly with mean standardized uptake value in scans performed 85 minutes post injection ( P &lt;0.001 and P =0.015, respectively). Subsequent multivariate analysis showed that CD163 correlated independently with 64 Cu-DOTATATE uptake ( P =0.031) whereas CD68 did not contribute significantly to the final model. Conclusions— The novel PET tracer 64 Cu-DOTATATE accumulates in atherosclerotic plaques of the carotid artery. CD163 gene expression correlated independently with 64 Cu-DOTATATE uptake measured by real-time quantitative polymerase chain reaction in the final multivariate model, indicating that 64 Cu-DOTATATE PET is detecting alternatively activated macrophages. This association could potentially improve noninvasive identification and characterization of vulnerable plaques.

Expression of fibromodulin in carotid atherosclerotic plaques is associated with diabetes and cerebrovascular events.

The small leucine-rich proteoglycans fibromodulin and lumican are functionally related extracellular matrix proteins involved in the regulation of collagen fiber formation. Fibromodulin-deficient apolipoprotein E-null mice have decreased vascular retention of lipids and reduced development of atherosclerosis suggesting that fibromodulin may influence the disease process. The aim of the present study was to investigate if fibromodulin and lumican are expressed in human carotid plaques and to determine if their expression is associated with the occurrence of preoperative symptoms and with risk for postoperative cardiovascular events. 153 plaques (51% symptomatic) obtained by carotid endarterectomy were included in this study. Plaque content was analyzed by immunohistochemistry and plaque cytokine content by multiplex technology. Fibromodulin and lumican were widely expressed in plaques and fibromodulin expression was significantly higher in symptomatic plaques. Expression of fibromodulin was significantly higher in plaques obtained from patients with diabetes and a high fibromodulin expression was associated with a higher incidence of post-operative cerebrovascular events, whereas no such associations were seen for lumican. Fibromodulin expression also correlated with plaque lipids and several pro-inflammatory cytokines. In addition, fibromodulin expression correlated with low levels of smooth muscle cells and the anti-inflammatory cytokine IL-10. These observations support previous experimental findings in mice for a role of fibromodulin in atherosclerosis and provide clinical evidence of the involvement of fibromodulin in the inflammatory processes that characterize atherosclerotic plaque vulnerability. They also suggest that this is of particular importance in diabetes.

18F]-sodium fluoride PET/CT is an imaging-derived biomarker of hydroxyapatite expression in carotid plaque: sub-study of the Canadian Atherosclerosis Imaging Network (CAIN-2)

Background: It has been hypothesized that [18F]-sodium fluoride (NaF) uptake imaged with positron emission tomography (PET) binds to hydroxyapatite molecules expressed in regions with active calcification. Therefore, we aimed to validate NaF as a marker of hydroxyapatite expression in high-risk carotid plaque. Methods: Eleven patients (69 ± 5 years, 3 female) scheduled for carotid endarterectomy were prospectively recruited for NaF PET/CT. One patient received a second contralateral endarterectomy; two patients were excluded (intolerance to contrast media and PET/CT misalignment). The bifurcation of the common carotid was used as the reference point; NaF uptake (tissue to blood ratio - TBR) was measured at every PET slice extending 2 cm above and below the bifurcation. Excised plaque was immunostained with Goldner’s Trichrome and whole-slide digitized images were used to quantify hydroxyapatite expression. Pathology was co-registered with PET. Results: NaF uptake was related to the extent of hydroxyapatite expression (r=0.45, p&lt;0.001). Upon classifying bilateral plaque for symptomatology, symptomatic plaque was associated with cerebrovascular events (3.75±1.1 TBR, n=9) and had greater NaF uptake than clinically silent asymptomatic plaque (2.79±0.6 TBR, n=11) (p=0.04). Conclusion: NaF uptake is related to hydroxyapatite expression and is increased in plaque associated with cerebrovascular events. NaF may serve as a novel biomarker of active calcification and plaque vulnerability.

The shape of middle cerebral artery and plaque location: high-resolution MRI finding.

The location of plaque may be associated with the vascular geometry. We aimed to examine the relationship between the geometry of middle cerebral artery and the plaque location detected by high-resolution magnetic resonance imaging. Among patients with a single subcortical infarction without a significant middle cerebral artery stenosis on magnetic resonance angiography, those with a plaque detected from high-resolution magnetic resonance imaging were prospectively enrolled. The shape of middle cerebral artery was measured from the coronal view, and was classified as straight, U-shaped, inverted U-shaped, and S-shaped. The location of the plaque was divided into superior and inferior, and analyzed according to the shape of middle cerebral artery. Among the 40 patients, the shape of middle cerebral artery was straight in 7 (17·5%), U-shaped in 10 (15·0%), inverted U-shaped in 11 (27·5%), and S-shaped in 12 patients (30·0%). The superior plaque was more closely associated with straight (85·7%) or U-shaped middle cerebral arteries (90·0%), whereas inverted U-shaped (81·8%) and S-shaped middle cerebral arteries (75·0%) were more often associated with inferior plaque. The prevalence of symptomatic plaque was higher in superior than inferior plaques (70·0% vs. 25·0%, P = 0·004). Multivariate analysis showed that straight and U-shaped middle cerebral artery was the only significant factor associated with the superior plaque. The shape of middle cerebral artery may be a factor determining the location of early atherosclerotic plaque.

0377 : Phosphoinositide 3-kinase gamma: a potential clinical target in the prevention of vascular damages inuced by arterial injury

Angioplasty with stent placement, used to treat symptomatic atherosclerosis plaques, is frequently complicated by restenosis. This pathology is characteried by fibroproliferative and immuno-inflammatory mechanisms of the arterial wall, called intimal hyperplasia (IH). Our previous results demonstrated that phosphoinositide 3-kinase (??(PI3K(??) was a key mediator of inflammatory processes of the arterial wall leading to atherosclerosis. We now proposed this enzyme as a potential clinical target to prevent vascular damages occuring after arterial lesion leading to IH. As cellular and molecular aspects of IH are still incompletely described, we intended to offer a better understanding ofimmune responses involved in this pathology. Using a mouse model of arterial mechanical injury, we showed that PI3K(?-deficient mice and mice expressing a catalytically-inactive PI3K(?(PI3K(?KD) showed reduced arterial occlusion and accumulation of monocytes and T cells around site of vascular lesion. The transfer of PI3K(?KD CD4 + T cells into Rag2-deficient mice greatly reduced vascular occlusion compared to WT cells, clearly demonstrating the involvement of PI3K(?in CD4 + T cells during IH formation. In addition, we found that IH is associated with increased levels of Th1 and Th17 cytokines. A specific decrease in the Th1 response was observed in the absence of PI3K(?activity, leading to decreased chemokine production by smooth muscle cells. Finally, we show that a short period of treatment with a PI3K(?inhibitor decreased IH development in arterial mechanical injury in mice but also in a rat carotid artery balloon injury model demonstrating the therapeutic potential of this inhibitor. Our work pintpoint PI3K(?as a good target for IH prevention and brings new insights in the immune biology of the disease.

Is cadmium exposure associated with the burden, vulnerability and rupture of human atherosclerotic plaques?

The general population is exposed to cadmium from food and smoking. Cadmium is a widely spread toxic pollutant that seems to be associated with cardiovascular diseases, although little is known if it contributes to the occurrence of atherosclerotic plaques and the process whereby plaques become vulnerable and are prone to rupture. We tested the hypotheses that cadmium exposure is associated not only with an increased subclinical burden of atherosclerotic plaques in different vascular territories and early signs of plaque vulnerability, but also with cadmium content and plaque-rupture in the clinical phase of the disease. Ultrasound technique was used to measure plaque prevalence and echogenicity in the carotid and femoral arteries in a population sample of women (n = 599) in whom blood cadmium was measured. In addition cadmium was measured in snap-frozen endarterectomies and whole blood obtained from patients who were referred to surgery because of symptomatic carotid plaques (n = 37). Sixteen endarterectomies were divided into three parts corresponding to different flow conditions and plaque vulnerability. In the population sample blood cadmium was associated with the number of vascular territories with plaques (p = 0.003 after adjustment for potential confounders). The cadmium concentrations in symptomatic plaques were 50-fold higher in plaque tissue than in blood. Cadmium levels in blood and plaque correlated, also after adjustment for smoking and other cardiovascular risk factors (p<0.001). Compared with the other parts of the plaque, the cadmium content was double as high in the part where plaque rupture usually occurs. In conclusion, the results show that cadmium exposure is associated with the burden of subclinical atherosclerosis in middle-aged women with different degrees of glucose tolerance, and that the content of cadmium in symptomatic plaques in patients is related to that in blood, but much higher, and preferentially located in the part of plaque where rupture often occurs.

Increased aldehyde-modification of collagen type IV in symptomatic plaques – A possible cause of endothelial dysfunction

ObjectiveSubendothelial LDL-adhesion and its subsequent oxidation are considered as key events in the development of atherosclerotic lesions. During oxidation of LDL, reactive aldehydes such as malondialdehyde (MDA) are formed, which modify apolipoprotein B100. However, the possibility that these reactive aldehydes could leak out of the LDL-particle and modify surrounding extracellular matrix proteins has been largely unexplored. We have investigated if aldehyde-modification of collagen type IV, one of the major basement membrane components, in plaques is associated with cardiovascular events. MethodsThe amount of MDA-modified collagen type IV and native collagen type IV were determined in homogenates from 155 carotid artery lesions, removed by endarterectomy from patients with or without previous cerebrovascular events. ResultsPlaque MDA-collagen type IV, but not native collagen type IV, correlated with oxidized LDL (r = 0.31, P < 0.001) and lipoprotein-associated phospholipase A2 (r = 0.44, P < 0.001). MDA-collagen type IV was increased in lesions from symptomatic patients compared to lesions from asymptomatic patients. Auto-antibodies against MDA-collagen type IV in plasma correlated with the amount of MDA-collagen type IV in lesions. MDA-modification of collagen type IV decreased endothelial cell attachment. In addition, culture of endothelial cells with MDA-modified collagen type IV increased vascular cell adhesion molecule expression and reduced the anti-coagulant proteins thrombomodulin and endothelial protein C receptor. In the lesions native collagen type IV, but not MDA-collagen type IV, was positively associated with thrombomodulin. ConclusionThe present observations imply that aldehyde-modification of collagen type IV, associated with LDL oxidation, in atherosclerotic plaques may cause endothelial dysfunction and increase the risk of clinical events.

Detection of Symptomatic Carotid Plaque Using Source Data from MR and CT Angiography: A Correlative Study

Background: Carotid plaque MRI has been a useful method to characterize vulnerable atherosclerotic plaque elements. Recent investigations have suggested that source images from CT angiography (CTA) and MR angiography (MRA) can identify the simple high-risk features of symptom-producing carotid artery plaque. We studied the correlation and relative diagnostic accuracies of CTA and MRA source images in detecting symptomatic carotid artery plaque. Methods: Subjects were eligible if they had carotid stenosis between 50 and 99% and had MRA and CTA exams performed within 10 days of one another. We measured the soft (non-calcified) plaque and hard (calcified) plaque thickness on CTA axial source images and intraplaque high-intensity signal (IHIS) on 3D-time-of-flight MRA source images in subjects. We assessed whether a correlation existed between increasing CTA soft plaque thicknesses and the presence of MRA IHIS using the Student's t-test. We calculated the differences in sensitivity and specificity measures of CTA and MRA source-imaging data with the occurrence of recent ipsilateral stroke or transient ischemic attack (TIA) as the reference standard. We also performed logistic regression analyses to evaluate the predictive strength of plaque showing both IHIS and increased CTA soft plaque thickness in predicting symptomatic disease status. Results: Of 1994 screened patients, 48 arteries met the final inclusion criteria with MRA and CTA performed within 10 days of one another. The mean and median time between CTA and MRA exams were 2.0 days and 1 day, respectively. A total of 34 of 48 stenotic vessels (70.8%) were responsible for giving rise to ipsilateral stroke or TIA. CTA mean soft plaque thickness was significantly greater (4.47 vs. 2.30 mm, p < 0.0001) in patients with MRA-defined IHIS, while CTA hard plaque thickness was significantly greater (2.09 vs. 1.16 mm, p = 0.0134) in patients without MRA evidence of IHIS. CTA soft plaque thickness measurements were more sensitive than MRA IHIS (91.2 vs. 67.6%, p = 0.011) in detecting symptomatic plaque, while differences in specificity were not significantly different (p = 0.1573). In the subset of patients with both IHIS on MRA and plaque thickness >2.4 mm on CTA, the odds ratio of detecting symptomatic plaque, corrected for stenosis severity, was 45.3 (p < 0.0005). Conclusions: Unprocessed source images from CTA and MRA, which are routinely evaluated for clinical studies demonstrate the highly correlated presence of IHIS and increasing soft plaque thickness. In particular, plaque that shows high-risk features on both MRA and CTA are very strongly associated with symptom-producing carotid plaque. With further validation, such techniques are promising practical methods of extracting risk information from routine neck angiographic imaging.

Abstract T P104: Remodeling of Intracranial Atherosclerotic Plaques

Background: Rupture-prone plaques may cause recurrent thrombo-embolic stroke. Little is known how symptomatic intracranial atherosclerotic plaques would remodel under current treatment. Method: We recruited acute stroke patients with high-grade (&gt;70%) symptomatic intracranial atherosclerotic stenosis for optimal medical treatment. Interval changes of plaque morphology were assessed by 3D-rotational angiography at baseline and 12 months. Morphological parameters included plaque surface (smooth/irregular/ulcerated), thickness, length (total length, maximal stenosis length), maximal stenosis distribution (proximal/central/distal), thickness-to-length ratio (ratio=thickness/total length), eccentricity, and plaque upstroke angulation. We stratified angiographic outcomes into 1) Progressive (surface morphology evolved from smooth to become irregular/ulcerated); 2) Static (surface morphology unchanged); and 3) Regressive (surface morphology from irregular/ulcerated to smooth). Results: Among the recruited 32 patients (age 66.3±8.9yrs, male 71.9%), we observed significant difference in plaque surface (ulcerated: 21.9% to 9.4%, p=0.01), thickness (1.54±0.41mm to 1.33±0.45mm, p=0.01), maximal stenosis distribution (central: 50.0% to 65.6%, p&lt;0.001), and thickness-to-length ratio (0.30±0.13 to 0.26±0.10, p=0.046). Plaque surface morphology remained unchanged in 25 patients (78.1%), progressive in 2 patients (6.3%), and regressive in 5 patients (15.6%, Figure). One patient (3%) developed recurrent ischemic stroke. Conclusion: Symptomatic intracranial atherosclerotic plaques may regress with medical therapy alone. Healing of ulcers and positive remodeling are evident in some plaques.

Abstract T MP29: Contrast-Enhanced Ultrasound is Useful for Detection of Vulnerable Plaques

Background and Purpose: Vulnerable plaques of carotid arteries are characterized as the presence of large necrotic core, intraplaque hemorrhage (IPH), intraplaque neovascularization (IPN), and active inflammation with thin fibrous cap. MRI is widely used for the qualitative evaluation of the plaques in vivo and the high-intensity plaques (HIP) on magnetization-prepared rapid acquisition with gradient echo (MPRAGE) images indicate containing necrotic cores with IPH, which indicates vulnerable plaques. However, we encounter the symptomatic cases without the presence of HIP on MPRAGE in clinical practice. Recent studies showed the efficacy for the evaluation of IPN using contrast-enhanced ultrasound (CEUS). We aimed to assess the vulnerability of the plaques without high intensity on MPRAGE images using CEUS. Methods: Between July 2010 and June 2014, we enrolled 69 patients with internal carotid artery stenosis who underwent carotid endarterectomy (CEA) and preoperatively examined CEUS and MRI (MPRAGE). All plaques were evaluated with CEUS and the contrast effects were classified semi-quantitatively (grade 0: absent, 1: small, 2: large, 3: extensive). We also divided the plaques into two groups (HIP group or non-HIP group) based on the signal intensity of the plaques on MPRAGE images. The results of MRI and CEUS were compared with histopathological findings of CEA specimens. Results: Fifty-eight plaques of all 69 patients showed HIP (41 were symptomatic), and eleven plaques were non-HIP (five were symptomatic: amaurosis fugax in three, cerebral infarction in two). In non-HIP group, symptomatic plaques were more enhanced (three in grade 2, two in grade 3) than asymptomatic plaques (one in grade 0, five in grade 1) using CEUS. Histopathological findings of all five CEA specimens from symptomatic patients showed that extensive IPN, large necrotic core, and active inflammation with thin fibrous cap which indicated vulnerable plaques, but small amount of IPH. These histological findings were compatible with the results of CEUS and MRI findings. Conclusion: CEUS may be useful for diagnosis of vulnerable plaques without high intensity on MPRAGE images.

Abstract T P180: Ultrasound Characteristics of Symptomatic Carotid Plaques: A Systematic Review and Meta-analysis

Background and Purpose: Ultrasound is the most commonly used imaging modality for assessment of carotid artery stenosis. A number of studies have demonstrated that surface irregularities, heterogeneous echotexture and hypoechoic plaques are risk factors for acute ischemic stroke. We performed a systematic review and meta-analysis of the literature to better define the risk of stroke based off of the sonographic characteristics of carotid plaques. Materials and Methods: We performed a comprehensive literature search evaluating the association of carotid plaque characteristics on ultrasound with ischemic outcomes. We included both case-control and cohort studies examining the relationship between complex plaque and acute ischemic stroke. Complex plaque was defined as plaque that had any of the following characteristics: heterogeneous plaque echogenicity, hypoechoic plaque, plaque neovascularization, plaque surface irregularity, plaque ulceration, and intraplaque motion. Meta-analyses using the random-effects model were performed for complex plaque and each of the individual complex plaque characteristics. Results: A total of 1013 articles were screened and 30 studies with 11528 patients (3054 symptomatic and 8474 asymptomatic) were included. The odds ratios for the association between complex plaque and ischemic symptoms was 5.18 (95%CI=4.63-5.79). Heterogeneous echotexture (OR=11.72, 95%CI=9.82-13.98), intraplaque motion (OR=1.57, 95%CI=1.02-2.41), plaque echolucency (OR=3.23, 95%CI=2.72-3.84), plaque neovascularity (OR=5.66, 95%CI=3.15-10.16) and plaque ulceration (OR=2.65, 95%CI=1.89-3.73) were all associated with ischemic symptoms. Surface irregularity without frank ulceration was not associated with ischemic symptoms (OR=1.35, 95%CI=0.98-1.86). Conclusions: Complex plaque, heterogeneous plaque echogenicity, hypoechoic plaque, plaque neovascularization, plaque ulceration and intraplaque motion are associated with ischemic symptoms. Assessment of carotid plaque on ultrasound provides stroke risk information beyond measurement of luminal stenosis.

Evolution of intracranial atherosclerotic disease under modern medical therapy.

Understanding how symptomatic intracranial atherosclerotic disease (ICAD) evolves with current medical therapy may inform secondary stroke prevention. In a prospective academic-initiated study, we recruited 50 patients (mean age = 63.4 ± 9.0 years) with acute strokes attributed to high-grade (≥70%) intracranial atherosclerotic stenosis for 3-dimensional rotational angiograms before and after intensive medical therapy for 12 months. Treatment targets included low-density lipoprotein ≤ 70mg/dl, glycosylated hemoglobin (HbA1c) ≤ 6.5%, and systolic blood pressure ≤ 140 mmHg. We analyzed infarct topography and monitored microembolic signal in recurrent strokes. The reference group was a published cohort of 143 ICAD patients. Overall, the stenoses regressed from 79% at baseline (interquartile range [IQR] = 71-87%) to 63% (IQR = 54-74%) in 1 year (p < 0.001). Specifically, the qualifying lesions (n = 49) regressed (stenosis reduced >10%) in 24 patients (49%), remained quiescent (stenosis same or ±10%) in 21 patients (43%), and progressed (stenosis increased >10%) in 4 patients (8%). There was no difference in intensity of risk factor control between groups of diverging clinical or angiographic outcomes. Higher HbA1c at baseline predicted plaque regression at 1 year (odds ratio = 4.4, 95% confidence interval = 1.4-14.5, p = 0.006). Among the 6 patients with recurrent strokes pertaining to the qualifying stenosis, 5 patients had solitary or rosarylike acute infarcts along the internal or anterior border zones, and 2 patients showed microembolic signals in transcranial Doppler ultrasound. A majority of symptomatic high-grade intracranial plaques had regressed or remained quiescent by 12 months under intensive medical therapy. Artery-to-artery thromboembolism with impaired washout at border zones was a common mechanism in stroke recurrence.