Morphological and Serological Criteria of Plaque Vulnerability: Risk Assessment for Symptomatic and Asymptomatic Carotid Artery Stenosis

Study Overview
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Brief Summary
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The aim of this study is to investigate the association of sonographic and histological features of the plaque among each other and with biomarkers of cardiovascular risk. The predictive value of these factors concerning the long-term clinical outcome after carotid endarterectomy will also be assessed. This may help to improve the identification of patients with carotid artery stenosis who will benefit most from carotid endarterectomy. The investigators major hypothesis is that the morphology of carotid plaques is associated with objectifiable sonographic parameters, in particular with the greyscale median. Second, the investigators hypothesize that sonographic and histological plaque morphology are associated with certain biomarkers of cardiovascular risk. Identification of 'vulnerable plaques' on the basis of a peripheral blood draw and a sonographic investigation may enable the treating physician to focus resources on patients who will benefit most form therapeutic interventions for primary prevention of ischemic stroke.

Detailed Description
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The indication for revascularization of carotid artery stenoses is typically based on the degree of stenosis and the presence of symptoms. Recent evidence suggests that the risk of embolization from an atherosclerotic plaque may be associated with plaque density as assessed sonographically by determination of the greyscale median. Also, an association of serum proteins vascular endothelial growth factor (VEGF), hypoxia inducible factor (HIF) and pigment epithelium-derived factor (PEDF), matrix metalloproteinases 2, 8 and 9 with unstable plaques has been reported. The VUCAP study will include patients undergoing carotid endarterectomy for symptomatic or asymptomatic carotid artery disease. Sonographic and serological markers of plaque vulnerability will be compared with histological features of the plaque and clinical presentation (symptomatic vs. asymptomatic). Preoperatively, the greyscale median of the plaque is assessed. Histomorphological investigation of the carotid plaques will be performed. Serological investigations will include markers of inflammation, thrombo-modulatory factors, lipid fractions and other parameters that have been associated with unstable plaques. The aim of the present study is to assess the ability of pigment epithelium-derived factor (PEDF), vascular endothelial growth factor (VEGF), hypoxia-induced factor 1 alpha (HIF 1-α), matrix metalloproteinases 2, 8 and 9 to differentiate between vulnerable and stable carotid artery plaques. Identification of 'vulnerable plaques' on the basis of a peripheral blood draw and a sonographic investigation may enable the treating physician to focus resources on patients who will benefit most form therapeutic interventions for primary prevention of ischemic stroke.

Official Title
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Morphological and Serological Criteria of Plaque Vulnerability: Risk Assessment for Symptomatic and Asymptomatic Carotid Artery Stenosis

Conditions
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Atherosclerosis, Carotid Artery Disease

Intervention / Treatment
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* Procedure: Carotid endarterectomy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: asymptomatic stenosis of internal carotid artery >70% symptomatic stenosis of internal carotid artery >60% planed surgical treatment of the stenosis Exclusion Criteria: pregnancy symptomatic coronary heart disease myocardial infarction or acute coronary syndrome in the past 3 months acute peripheral artery occlusion in the past 3 months immaturity existence of a guardianship

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| carotid artery stenosis<br>Patients with symptomatic or asymptomatic carotid artery stenosis indicated for carotid endarterectomy, who provide written informed consent, will be included in this study. The investigators will compare patients ultrasonographic data, serum laboratory analyses and histomorphological preferances to look for biomarkers for the plaque instability. | Procedure: Carotid endarterectomy<br>* Carotid endarterectomy is a surgery used to reduce the risk of stroke, by correcting stenosis in the carotid artery. Endarterectomy is the removal of material on the inside (end-) of an artery.An incision is made on the midline side of the Sternocleidomastoid muscle. The incision is between 5 and 10 cm in length. Then the patients get 5000 IU heparin by the anesthesia. The internal, common and external carotid arteries are carefully identified, controlled with vessel loops, and clamped. The lumen of the internal carotid artery is opened, and the atheromatous plaque removed. The artery is closed using suture. The procedure is performed under local anesthesia. Local anesthesia, opposite to general, allows for direct monitoring of neurological status by intra-operative verbal contact and testing of grip strength.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| serum levels of PEDF, VEGF, HIF-1 alpha, MMP-2, -8 and -9 compared to histomorphological classification of the plaque based on AHA classification and ultrasonographic data- grey scale median (GSM) | Extended sonomorphological investigation will be performed by a sonographer blinded to patients' characteristics, for the assessment of grey scale median (GSM). After removal plaques will be fixated in RNAlater for further RNA-determinations. In addition, histomorphological characterization of the plaque will be performed and the plaque classified based on the American Heart Association (AHA) classification. RNA-determination will focus on the expression levels of PEDF. VEGF, HIF-1 alpha, MMP-2, -8 and -9. For that purpose we will perform RNA isolation from the tissue, transcription to cDNA and also a quantitative real-time PCR. Furthermore immunostaining of the plaque with PEDF, VEGF, HIF-1 alpha, MMP-2, -8 and -9 antibodies to determine the distribution of those proteins within the plaques will be done. | ultrasonographical data are assessed a day before the surgery, carotid artery plaque will be taken during the surgery, whole blood on the day of operation, | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change in blood serum levels as well as protein level expression of PEDF, VEGF, HIF-1 alpha, MMP-2, -8 and -9 after plaque removal | enzyme-linked immunosorbent assay (ELISA) will be done for the determination of PEDF, VEGF, HIF-1 alpha, before and after surgery | serum blood levels are evaluated from the whole blood twice: on the day of surgery and 6 weeks after removal of the plaque | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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stroke, biomarkers, vulnerable plaque, carotid endarterectomy, carotid artery disease