Ten-year risk of stroke in patients with previous cerebral infarction and the impact of carotid surgery in the Asymptomatic Carotid Surgery Trial

Optimised medical therapy alone versus optimised medical therapy plus revascularisation for asymptomatic or low-to-intermediate risk symptomatic carotid stenosis (ECST-2): 2-year interim results of a multicentre randomised trial

BACKGROUND

Carotid revascularisation, comprising either carotid endarterectomy or stenting, is offered to patients with carotid stenosis to prevent stroke based on the results of randomised trials conducted more than 30 years ago. Since then, medical therapy for stroke prevention has improved. We aimed to assess whether patients with asymptomatic and symptomatic carotid stenosis with a low or intermediate predicted risk of stroke, who received optimised medical therapy (OMT), would benefit from additional revascularisation.

METHODS

The Second European Carotid Surgery Trial (ECST-2) is a multicentre randomised trial with blinded outcome adjudication, which was conducted at 30 centres with stroke and carotid revascularisation expertise in Europe and Canada. Patients aged 18 years or older with asymptomatic or symptomatic carotid stenosis of 50% or greater, and a 5-year predicted risk of ipsilateral stroke of less than 20% (estimated using the Carotid Artery Risk [CAR] score), were recruited. Patients were randomly assigned to either OMT alone or OMT plus revascularisation (1:1) using a web-based system. The primary outcome for this 2-year, interim analysis was a hierarchical outcome composite of: (1) periprocedural death, fatal stroke, or fatal myocardial infarction; (2) non-fatal stroke; (3) non-fatal myocardial infarction; or (4) new silent cerebral infarction on imaging. Analysis was by intention-to-treat using the win ratio-ie, each patient in the OMT alone group was compared as a pair with each patient in the OMT plus revascularisation group, with a win declared for the patient with a better outcome within the pair (a tie was declared if neither patient in the pair had a better outcome). The win ratio was calculated as the number of wins in the OMT alone group divided by the number of wins in the OMT plus revascularisation group. This trial is registered with the ISRCTN Registry (ISRCTN97744893) and is ongoing.

FINDINGS

Between March 1, 2012, and Oct 31, 2019, 429 patients were randomly assigned to OMT alone (n=215) or OMT plus revascularisation (n=214). One patient allocated to OMT alone withdrew consent within 48 h and was not considered further. The median age of patients was 72 years (IQR 65-78); 296 (69%) were male and 133 (31%) female. No benefit was recorded in favour of either treatment group with respect to the primary hierarchical outcome assessed 2 years after randomisation, with 5228 (11·4%) wins for the OMT alone group, 5173 (11·3%) wins for the OMT plus revascularisation group, and 35 395 (77·3%) ties between groups (win ratio 1·01 [95% CI 0·60-1·70]; p=0·97). For OMT alone versus OMT plus revascularisation, four versus three patients had periprocedural death, fatal stroke, or fatal myocardial infarction; 11 versus 16 had non-fatal stroke; seven versus five had non-fatal myocardial infarction; and 12 versus seven had new silent cerebral infarction on imaging. One periprocedural death occurred in the OMT plus revascularisation group, which was attributed to decompensated aortic stenosis 1 week after carotid endarterectomy.

INTERPRETATION

No evidence for a benefit of revascularisation in addition to OMT was found in the first 2 years following treatment for patients with asymptomatic or symptomatic carotid stenosis of 50% or greater with a low or intermediate predicted stroke risk (assessed by the CAR score). The results support treating patients with asymptomatic and low or intermediate risk symptomatic carotid stenosis with OMT alone until further data from the 5-year analysis of ECST-2 and other trials become available.

FUNDING

National Institute for Health and Care Research; Stroke Association; Swiss National Science Foundation; Dutch Organisation for Knowledge and Innovation in Health, Healthcare and Well-Being; Leeds Neurology Foundation.

Long-Term Stroke Risk in Patients With New Ischemic Brain Lesions on MRI After Carotid Revascularization

BACKGROUND

Carotid artery revascularization can result in new ischemic brain lesions on diffusion-weighted magnetic resonance imaging. This study aimed to investigate the relationship between periprocedural ischemic diffusion-weighted imaging (DWI) lesions after carotid artery revascularization and recurrent long-term cerebrovascular events.

METHODS

A secondary observational prospective cohort analysis of existing clinical trial data was performed on 162 patients with symptomatic carotid stenosis that were previously randomized to carotid artery stenting or carotid endarterectomy in the ICSS (International Carotid Stenting Study) and included in the magnetic resonance imaging substudy. Magnetic resonance imagings were performed 1 to 7 days before and 1 to 3 days after treatment. The primary composite clinical outcome was the time to any stroke or transient ischemic attack during follow-up. Patients with new diffusion-weighted imaging (DWI) lesions on posttreatment magnetic resonance imaging scan (DWI+) were compared with patients without new lesions (DWI-).

RESULTS

The median time of follow-up was 8.6 years (interquartile range, 5.0-12.5). Kaplan-Meier cumulative incidence for the primary outcome after 12.5-year follow-up was 35.3% (SE, 8.9%) in DWI+ patients and 31.1% (SE, 5.6%) in DWI- patients. Uni- and multivariable regression analyses did not show significant differences (hazard ratio, 1.50 [95% CI, 0.76-2.94] and hazard ratio, 1.30 [95% CI, 0.10-1.02], respectively). Higher event rate of the primary outcome in DWI+ patients in the overall cohort was mainly caused by events in the carotid artery stenting group.

CONCLUSIONS

Based on our outcome analysis within the ICSS magnetic resonance imaging substudy, DWI lesions following carotid revascularization did not seem to have a relationship with long-term stroke risk.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: ISRCTN 25337470.

Contemporary Treatment of the Asymptomatic Carotid Patient

Stroke is a persistent leading cause of morbidity and mortality, and carotid artery atherosclerosis remains a treatable cause of future stroke. Although most patients with asymptomatic carotid artery disease may be at a relatively low risk for future stroke, most completed strokes are unheralded; thus, the identification and appropriate treatment of patients with asymptomatic carotid artery disease remains a critical part of overall stroke prevention. Select patients with asymptomatic carotid artery stenosis with an increased risk of future stroke based on the degree of stenosis and other imaging or patient-related characteristics are appropriate to consider for carotid artery intervention.

Cohort study on the prognosis of acute cerebral infarction in different circulatory systems at 1-year follow-up

Background

To evaluate the prognosis of acute cerebral infarction at 1-year follow-up in different circulation infarctions.

Methods

Clinical data of 858 consecutive patients with acute cerebral infarction were collected. Of the 858 cases, 21 (2.45%) were lost to follow-up and 837 completed follow-up and thus were enrolled in this study. At 1-year follow-up, death or moderate-to-severe dysfunction (modified Rankin Scale (mRS) ≥ 3 points) was regarded as the poor prognostic endpoint. Univariate analysis and multivariate logistic stepwise regression analysis were performed to assess the prognosis. The prediction probability of indicators was obtained for the multivariate model, and the receiver operating characteristic curve was delineated to calculate the area under the curve (AUC) to predict the fitness of the model.

Results

The older the age, the greater the probability of a poor prognosis. Patients with previous diabetes and cerebral infarction had a poor prognosis. The higher the National Institutes of Health Stroke Scale and mRS scores and the lower the Barthel index at admission, the worse the prognosis of the patients. The longer the hospital stay, the worse the prognosis of the patients. The prognosis of different circulation infarctions was different. The AUC of the multivariate model was AUC = 0.893, and the 95% confidence interval was 0.870–0.913, indicating a good fit. The prognosis of anterior circulation infarction (ACI) was worse than that of posterior circulation infarction (PCI) (P < 0.05). The prognosis of patients with ACI and PCI was not significantly different from that of patients with ACI or PCI alone (P > 0.05).

Conclusions

Diabetes, the Barthel index at admission and previous cerebral infarction are poor prognostic factors of acute cerebral infarction. The prognosis of ACI is worse than that of PCI. Different factors affect the prognosis of different circulatory system infarctions.

The TAXINOMISIS Project: A multidisciplinary approach for the development of a new risk stratification model for patients with asymptomatic carotid artery stenosis

INTRODUCTION

Asymptomatic carotid artery stenosis (ACAS) may cause future stroke and therefore patients with ACAS require best medical treatment. Patients at high risk for stroke may opt for additional revascularization (either surgery or stenting) but the future stroke risk should outweigh the risk for peri/post-operative stroke/death. Current risk stratification for patients with ACAS is largely based on outdated randomized-controlled trials that lack the integration of improved medical therapies and risk factor control. Furthermore, recent circulating and imaging biomarkers for stroke have never been included in a risk stratification model. The TAXINOMISIS Project aims to develop a new risk stratification model for cerebrovascular complications in patients with ACAS and this will be tested through a prospective observational multicentre clinical trial performed in six major European vascular surgery centres.

METHODS AND ANALYSIS

The risk stratification model will compromise clinical, circulating, plaque and imaging biomarkers. The prospective multicentre observational study will include 300 patients with 50%-99% ACAS. The primary endpoint is the three-year incidence of cerebrovascular complications. Biomarkers will be retrieved from plasma samples, brain MRI, carotid MRA and duplex ultrasound. The TAXINOMISIS Project will serve as a platform for the development of new computer tools that assess plaque progression based on radiology images and a lab-on-chip with genetic variants that could predict medication response in individual patients.

CONCLUSION

Results from the TAXINOMISIS study could potentially improve future risk stratification in patients with ACAS to assist personalized evidence-based treatment decision-making.

Impact of cerebral ischemic lesions on the outcome of carotid endarterectomy

Patients with carotid artery stenosis (CAS) are commonly defined as asymptomatic or symptomatic according with their neurological conditions, however, emerging evidences suggest stratifying patients according also with the presence of cerebral ischemic lesions (CIL). In asymptomatic patients, the presence of CIL increases the risk of future neurologic event from 1% to 4% per year, leading to a stronger indication to carotid revascularization. In symptomatic patients, the presence of CIL does not seem to influence the outcome of the carotid revascularization if the volume of the lesion is small (<4,000 mm³); the benefit of the revascularization is also more significant if performed within 2 weeks from the index event. However, high volume (>4,000 mm³) CIL are associated in some experiences with a higher risk of carotid revascularization suggesting to delay the carotid revascularization for at least 4 weeks. As a matter of fact, the evaluation of CIL dimensions and characteristics in patients with CAS gives to the physician involved in the treatment a valuable adjunctive tool in the choice of the ideal treatment.

Predictors and Consequences of Silent Brain Infarction in Patients with Asymptomatic Carotid Stenosis

AIM

Silent brain infarction (SBI) is associated with an increased risk of stroke in patients with asymptomatic carotid stenosis (ACS), and is therefore one of the criteria for performing carotid endarterectomy (CEA). Despite an extensive literature, this issue is still a matter of debate. Aim of the present work was to evaluate incidence and predictors of SBI in patients undergoing CEA for ACS, and to investigate its possible impact on CEA outcome.

METHODS

All patients submitted to CEA in a single academic center from 2005 to 2019 were prospectively inserted into a specific database. The presence of SBI was evaluated by preoperative computed tomography (CT), considering exclusively infarctions in the carotid territories from an athero-embolic source. Preoperative characteristics were investigated as possible risk factor for SBI at the uni- and multivariate analysis. The impact of SBI on stroke occurrence after CEA was also evaluated.

RESULTS

In the designated period, over a total of 1288 ACS considered and submitted to CEA, 105 (8.2%) were associated with SBI. Male sex, hypertension, dyslipidaemia, smoking, contralateral carotid occlusion and severity of carotid stenosis were associated with SBI at the univariate analysis; preoperative statin therapy showed to be a protective factor. At the multivariate analysis, contralateral carotid occlusion and severity of stenosis were independently associated with SBI (OR: 3.16, 95%CI 1.62-6.18, P=.001; OR: 1.04, 95%CI 1.01-1.07, P=.004, respectively), with statin therapy confirmed as a protective factor (OR: 0.60, 95%CI: 0.40-0.92, P=.002). Overall post-CEA stroke rate was 0.9%, with a higher post-operative risk independently predicted by the presence of SBI (OR:4.23, 95%CI: 1.40-12.73, P=.01).

CONCLUSION

SBI is present in 8% of patients with ACS, and is significantly associated with contralateral carotid occlusion and severity of the carotid stenosis. Statin therapy reduces the occurrence of this phenomenon. The presence of SBI should be carefully considered in indication to CEA since it significantly increases the surgical risk.

Cerebral Small Vessel Disease in Standard Pre-operative Imaging Reports Is Independently Associated with Increased Risk of Cardiovascular Death Following Carotid Endarterectomy

OBJECTIVE

Cerebral white matter lesions (WMLs) and lacunar infarcts are surrogates of cerebral small vessel disease (SVD). WML severity as determined by trained radiologists predicts post-operative stroke or death in patients undergoing carotid endarterectomy (CEA). It is unknown whether routine pre-operative brain imaging reports as part of standard clinical practice also predict short and long term risk of stroke and death after CEA.

METHODS

Consecutive patients from the Athero-Express biobank study that underwent CEA for symptomatic high degree stenosis between March 2002 and November 2014 were included. Pre-operative brain imaging (computed tomography [CT] or magnetic resonance imaging [MRI]) reports were reviewed for reporting of SVD, defined as WMLs or any lacunar infarcts. The primary outcome was defined as any stroke or any cardiovascular death over three year follow up. The secondary outcome was defined as the 30 day peri-operative risk of stroke or cardiovascular death.

RESULTS

A total of 1038 patients were included (34% women), of whom 659 (63.5%) had CT images and 379 (36.5%) MRI images available. Of all patients, 697 (67%) had SVD reported by radiologists. Patients with SVD had a higher three year risk of cardiovascular death than those without (6.5% vs. 2.1%, adjusted HR 2.52 [95% CI 1.12-5.67]; p = .026) but no association was observed for the three year risk of stroke (9.0% vs. 6.7%, for patients with SVD vs. those without, adjusted HR 1.24 [95% CI 0.76-2.02]; p = .395). No differences in 30 day peri-operative risk were observed for stroke (4.4% vs. 2.9%, for patients with vs. those without SVD; adjusted HR 1.49 [95% CI 0.73-3.05]; p = .28), and for the combined stroke/cardiovascular death risk (4.4% vs. 3.5%, adjusted HR 1.20 [95% CI 0.61-2.35]; p = .59).

CONCLUSION

Presence of SVD in pre-operative brain imaging reports can serve as a predictor for the three year risk of cardiovascular death in symptomatic patients undergoing CEA but does not predict peri-operative or long term risk of stroke.

Gadolinium Enhancement of the Aneurysm Wall in Extracranial Carotid Artery Aneurysms

BACKGROUND AND PURPOSE

The natural history and optimal treatment of extracranial carotid artery aneurysms are unknown. Gadolinium enhancement of the aneurysm wall may reflect aneurysm wall inflammation and instability. In this study, we investigated the feasibility of extracranial carotid artery aneurysm wall imaging and explored a potential relationship of aneurysm wall enhancement with aneurysm growth and the presence of (silent) brain infarcts and white matter lesions.

MATERIALS AND METHODS

Fourteen conservatively treated patients with 15 asymptomatic extracranial carotid artery aneurysms underwent gadolinium-enhanced 3T MR imaging at 2 time points with a 12-month interval. Primary outcome was growth of the aneurysm sac (≥2.0 mm); secondary outcomes were the presence of (silent) brain infarcts and white matter lesions at baseline and follow-up. MR images were reviewed by 2 independent observers, and inter- and intraobserver reproducibility was assessed.

RESULTS

Seven (50%) patients were men; the median age was 55 years (range, 40-69 years). Eleven extracranial carotid artery aneurysms (73%) were saccular (median size, 11 mm; range, 5.0-38.5 mm), and 4 were fusiform (median size, 21.5 mm; range, 10.0-40.0 mm). Eleven of 15 aneurysms (73%) exhibited gadolinium enhancement at baseline. Four aneurysms (27%) showed growth at follow-up imaging, 2 gadolinium-positive (+) and 2 gadolinium-negative (-) (P = .245). Three patients (21%) had ipsilateral brain infarcts at baseline; 1 of them showed a new silent brain infarct at follow-up imaging (gadolinium+). Nine patients (64%) showed bilateral white matter lesions at baseline. In 3 patients, increased white matter lesion severity was observed at follow-up (2 gadolinium+). All observations showed excellent inter- and intraobserver reproducibility.

CONCLUSIONS

In this explorative study, we demonstrated that extracranial carotid artery aneurysm wall imaging was feasible. Future well-powered studies are needed to investigate whether extracranial carotid artery aneurysm gadolinium enhancement predicts aneurysm growth and thromboembolic complications.

Poor long-term outcomes after carotid endarterectomy: a retrospective analysis of two portuguese centers

Objetives. Carotid endarterectomy (CEA) is an established treatment for carotid stenosis (CS). However, this procedure is not risk-free and it is insufficient to control disseminated atherosclerosis. Our aim was to determine long-term cardiovascular morbidity and mortality after CEA and identify associated risk predictors. Design. Consecutive cohorts of CEAs performed between 2010 and 2018 in two Portuguese hospitals were retrospectively analysed. The major end-points were acute myocardial infarction (AMI), stroke, all-cause death and major adverse cardiovascular events (MACE). Results. 248 patients (mean age 69 years; 79% male) were enrolled in the study. 24% had postoperative complications. At 52 months median follow-up, 9 ± 2.0% (mean ± standard error) of patients experienced an acute myocardial infarction (AMI), 12 ± 2.4% a stroke and 26 ± 3.2% a MACE. All-cause mortality rate was 21 ± 3.0%. Multivariate analysis identified coronary artery disease (CAD) as significant predictor of AMI (p < .001; Hazard Ratio (HR):9.628; 95% Confidence Interval (95%CI):2.805-33.046), whereas no statistically significant risk factor of stroke was found. Predictors of death included left sided CS (p = .042; HR:1.886; 95%CI:1.024-3.475), chronic kidney disease (CKD) (p = .007; HR:2.352; 95%CI:1.266-4.372) and anticoagulant medication (p = .015; HR:2.107; 95%CI:1.216-6.026), while statin use was significantly protective (p = .049; HR:0.482; 95%CI:0.233-0.998). Concerning MACE, male gender (p = .040; HR:1.709; 95%CI:1.025-2.849), tobacco use (p = .004; HR:2.181; 95%CI:1.277-3.726), CAD (p = .002; HR:2.235; 95%CI:1.340-3.727) and CKD (p < .001; HR:3.029; 95%CI:1.745-5.258) were risk predictors. Conclusions. Patients continue to have high rates of AMI, MACE and death after CEA. Prior CAD is a risk factor for future AMI, whereas CKD is a significant predictor of MACE and death. Aggressive best medical treatment and risk factors modification should be advised in all patients with systemic atherosclerosis.

Asymptomatic carotid stenosis and concomitant silent brain infarctions

Objectives

This review aims to clarify (1) the definition of silent brain infarct (SBI), (2) the diagnostic criteria of SBI using magnetic resonance imaging (MRI), (3) the prevalence of patients with asymptomatic carotid stenosis and SBI based on MRI assessment, (4) the association of SBI and asymptomatic carotid stenosis and the risk of stroke compared to patients without SBI, (5) the association between development of dementia/cognitive impairment in people with asymptomatic carotid stenosis and SBI, and (6) the evidence for treating patients with carotid stenosis and SBI.

Methods

A systematic search of PubMed and Scopus including all studies published from 2000 to 2018 and written in English.

Results

No consensus of the definition and diagnostic criteria for SBI was found. The prevalence of SBI in asymptomatic carotid patients is 17–33.3%. SBI is a significant risk factor for future stroke, OR 4.6 (95% CI: 3.0–7.2; p < 0.0001). One substudy showed that immediate CEA is beneficial compared to delayed CEA in these patients, showing a 45% reduction in annual stroke rate from 1.5%/year to 0.7%/year.

Conclusion

This review emphasizes the need to standardize the definition and diagnostic criteria of SBI on MRI. Current evidence suggests an increased risk and a small potential benefit of offering carotid endarterectomy to patient with silent brain infarct. Prospective studies are warranted to elucidate these issues further.

Identifying asymptomatic patients at high-risk for stroke

Carotid endarterectomy and carotid artery stenting, in addition to good medical therapy, halve long-term stroke risk in asymptomatic patients with carotid artery stenosis. Since the absolute benefits following successful intervention are moderate, identification of asymptomatic patients at high-risk of future stroke could maximize the effectiveness of carotid interventions. The aim of this paper is to summarize the evidence for high-risk features associated with increased long-term stroke risk in asymptomatic patients. There is a paucity of reliable data describing the effect of clinical features, imaging findings and plaque characteristics on increased long-term stroke risk. Clinical and imaging features such as contralateral symptoms, silent brain infarcts/embolic signals, progression of stenosis and impaired cerebrovascular reactivity may be associated with increased future risk of stroke. Plaque characteristics such as echolucency, large plaque size (≥80 mm), intra-plaque hemorrhage, lipid-rich necrotic core and thinned/ruptured fibrous cap may also increase future risk of stroke. Whilst these form the basis for European guidelines targeting carotid intervention in asymptomatic patients with tight stenosis, conclusive evidence of their utility is lacking. Results from ongoing large, multicenter randomized clinical trials comparing carotid endarterectomy and carotid artery stenting with good medical therapy may be consistent with earlier trials, showing a halving of the long-term risk of stroke following successful carotid revascularization. However, they may well lack sufficient statistical power to identify higher-risk subgroups in whom the absolute gains of treatment are significantly higher. Large contemporary cohort studies are needed to provide further clarity regarding high-risk features associated with increased long-term stroke risk in asymptomatic patients with carotid artery stenosis.

The Asymptomatic Carotid Surgery Trial-2 (ACST-2): an ongoing randomised controlled trial comparing carotid endarterectomy with carotid artery stenting to prevent stroke

BACKGROUND

A successful open surgical operation to remove atheromatous carotid artery narrowing that has not yet caused a stroke (asymptomatic carotid stenosis) carries some procedural risk but, if completed successfully, halves patients' future annual stroke risk for at least 10 years. A newer, less invasive alternative is carotid stenting, which also carries some procedural risk, especially if the carotid lesion has recently given rise to a stroke (symptomatic carotid stenosis). For both surgery and stenting, improvements in technique (and in medication) have reduced risk. Early studies showed that treating carotid narrowing by stenting, particularly for symptomatic lesions, caused more procedural minor strokes than surgery, but more recent trials in symptomatic and in asymptomatic patients found that both procedures might now be equally safe and effective. However, low patient numbers, short follow-up of the long-term effects on stroke rates and wide confidence intervals mean that worldwide uncertainty persists between carotid surgery and carotid stenting, and national and international guidelines remain unclear as to which is generally better.

OBJECTIVES

The second Asymptomatic Carotid Surgery Trial (ACST-2) compares carotid endarterectomy (CEA) with carotid artery stenting (CAS) directly, randomising patients with asymptomatic carotid stenosis for whom a carotid procedure is considered definitely necessary; both procedures seem anatomically feasible, and there is substantial uncertainty as to which of the two would be better for such individuals. Although it will compare procedural risks, the trial's primary aim is to compare the long-term durability of protection against strokes occurring in the years post procedure due to any remaining or recurrent carotid disease.

DESIGN

Randomised controlled trial comparing CEA with CAS.

SETTING

Hospitals in the UK and worldwide, in which carotid procedures are common.

PARTICIPANTS

Men and women with severely stenotic atherosclerotic carotid artery disease, with or without previous stroke but with no recent symptoms from the randomised artery.

INTERVENTIONS

CEA and CAS.

OUTCOMES

(1) Periprocedural risk defined as myocardial infarction, stroke or death within 30 days after the randomised procedure and (2) long-term rates of disabling or fatal stroke during follow-up of patients.

MEASUREMENT OF COSTS AND OUTCOMES

Measurement of intervention costs and stroke costs (periprocedural and during follow-up) and of quality of life [EuroQol-5 Dimensions (EQ-5D^®)] for patients in the top six recruiting countries (UK, Italy, Belgium, Germany, Serbia and Sweden), who currently constitute 85% of those randomised.

PROGRESS SO FAR

By the end of March 2016, ACST-2 had included 2125 patients, nearly two-thirds of the planned recruitment of 3600; 1061 were randomly allocated to CEA and 1064 to CAS.

CONCLUSIONS

Further funding has been secured and recruitment continues, with completion anticipated by the end of 2019. ACST-2 will report initial results in 2021.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN21144362.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 57. See the NIHR Journals Library website for further project information. Funding was also received from BUPA Foundation [BUPAF/33(a)/05].

Endothelial vascular cell adhesion molecule 1 is a marker for high-risk carotid plaques and target for ultrasound molecular imaging

BACKGROUND

Molecular imaging of carotid plaque vulnerability to atheroembolic events is likely to lead to improvements in selection of patients for carotid endarterectomy (CEA). The aims of this study were to assess the relative value of endothelial inflammatory markers for this application and to develop molecular ultrasound contrast agents for their imaging.

METHODS

Human CEA specimens were obtained prospectively from asymptomatic (30) and symptomatic (30) patients. Plaques were assessed by semiquantitative immunohistochemistry for vascular cell adhesion molecule 1 (VCAM-1), lectin-like oxidized low-density lipoprotein receptor 1, P-selectin, and von Willebrand factor. Established small peptide ligands to each of these targets were then synthesized and covalently conjugated to the surface of lipid-shelled microbubble ultrasound contrast agents, which were then evaluated in a flow chamber for binding kinetics to activated human aortic endothelial cells under variable shear conditions.

RESULTS

Expression of VCAM-1 on the endothelium of CEA specimens from symptomatic patients was 2.4-fold greater than that from asymptomatic patients (P < .01). Expression was not significantly different between groups for P-selectin (P = .43), von Willebrand factor (P = .59), or lectin-like oxidized low-density lipoprotein receptor 1 (P = .99). Although most plaques from asymptomatic patients displayed low VCAM-1 expression, approximately one in five expressed high VCAM-1 similar to plaques from symptomatic patients. In vitro flow chamber experiments demonstrated that VCAM-1-targeted microbubbles bind cells that express VCAM-1, even under high-shear conditions that approximate those found in human carotid arteries, whereas binding efficiency was lower for the other agents.

CONCLUSIONS

VCAM-1 displays significantly higher expression on high-risk (symptomatic) vs low-risk (asymptomatic) carotid plaques. Ultrasound contrast agents bearing ligands for VCAM-1 can sustain high-shear attachment and may be useful for identifying patients in whom more aggressive treatment is warranted.

Relationship between Calcification and Vulnerability of the Carotid Plaques

BACKGROUND

Carotid plaques with a high degree of calcification are usually considered at low embolic risk. However, since a precise evaluation of the extent of calcification is not possible preoperatively through duplex ultrasound and postoperatively by conventional histological examination due to the decalcification process, the relationship between the amount of calcium involvement and plaque vulnerability has not been evaluated yet. This study aims to correlate the extent of carotid plaque calcification with clinical, radiological, and histological complications.

METHODS

Symptomatic and asymptomatic consecutive patients submitted to carotid endarterectomy between January to December 2014 were included in the study. The amount of carotid calcification was assessed at preoperative computed tomography (CT) through measurement of thickness and circumferential calcium extension and graded from 1 to 8 accordingly (Babiarz classification). Patients were then categorized into 2 groups (low-level group: grade 1-5; high-level group: grade 6-8) and correlated with clinical characteristics and ipsilateral cerebral ischemic lesions at CT. Vulnerability of the plaque was assessed histologically according with American Heart Association (AHA) Classification. Results were overall blindly correlated.

RESULTS

One hundred five patients (81% male; age: 73 ± 8 years) were enrolled in the study. Forty (38%) were symptomatic and 43 (40%) had an ipsilateral focal lesion at preoperative cerebral CT. Thirty-six (38%) patients had high-level carotid calcification degree at CT scan. At histological analysis, 56 (56%) plaques were considered complicated (AHA type VI). Patients with high-level and low-level carotid calcification had similar epidemiological risk factors, preoperative neurological symptoms, and histological complications (17% vs. 15%, P = 0.76 and 50% vs. 55%, P = 0.62, respectively). The high-level calcification group showed a significantly higher incidence of ipsilateral cerebral lesions at preoperative CT (56% vs. 32%, P = 0.01).

CONCLUSIONS

A high level of calcification of the carotid plaque is not necessarily associated with lower vulnerability: the incidence of preoperative neurological symptoms and histological complications is similar in patients with and without extensive carotid plaque calcification. Cerebral ischemic lesions may be even more frequent in the presence of highly calcified plaques.