Relationship of Carotid Plaque Echomorphology to Presenting Symptom

Carotid plaque surface echogenicity predicts cerebrovascular events: An Echographic Multicentric Swiss Study

BACKGROUND AND PURPOSE

To determine the prognostic value for ischemic stroke or transitory ischemic attack (TIA) of plaque surface echogenicity alone or combined to degree of stenosis in a Swiss multicenter cohort METHODS: Patients with ≥60% asymptomatic or ≥50% symptomatic carotid stenosis were included. Grey-scale based colour mapping was obtained of the whole plaque and of its surface defined as the regions between the lumen and respectively 0-0.5, 0-1, 0-1.5, and 0-2 mm of the outer border of the plaque. Red, yellow and green colour represented low, intermediate or high echogenicity. Proportion of red color on surface (PRCS) reflecting low echogenictiy was considered alone or combined to degree of stenosis (Risk index, RI).

RESULTS

We included 205 asymptomatic and 54 symptomatic patients. During follow-up (median/mean 24/27.7 months) 27 patients experienced stroke or TIA. In the asymptomatic group, RI ≥0.25 and PRCS ≥79% predicted stroke or TIA with a hazard ratio (HR) of respectively 8.7 p = 0.0001 and 10.2 p < 0.0001. In the symptomatic group RI ≥0.25 and PRCS ≥81% predicted stroke or TIA occurrence with a HR of respectively 6.1 p = 0.006 and 8.9 p = 0.001. The best surface parameter was located at 0-0.5mm. Among variables including age, sex, degree of stenosis, stenosis progression, RI, PRCS, grey median scale values and clinical baseline status, only PRCS independently prognosticated stroke (p = 0.005).

CONCLUSION

In this pilot study including patients with at least moderate degree of carotid stenosis, PRCS (0-0.5mm) alone or combined to degree of stenosis strongly predicted occurrence of subsequent cerebrovascular events.

Roadmap Consensus on Carotid Artery Plaque Imaging and Impact on Therapy Strategies and Guidelines: An International, Multispecialty, Expert Review and Position Statement

Current guidelines for primary and secondary prevention of stroke in patients with carotid atherosclerosis are based on the quantification of the degree of stenosis and symptom status. Recent publications have demonstrated that plaque morphology and composition, independent of the degree of stenosis, are important in the risk stratification of carotid atherosclerotic disease. This finding raises the question as to whether current guidelines are adequate or if they should be updated with new evidence, including imaging for plaque phenotyping, risk stratification, and clinical decision-making in addition to the degree of stenosis. To further this discussion, this roadmap consensus article defines the limits of luminal imaging and highlights the current evidence supporting the role of plaque imaging. Furthermore, we identify gaps in current knowledge and suggest steps to generate high-quality evidence, to add relevant information to guidelines currently based on the quantification of stenosis.

Ficolin-2 serum levels predict the occurrence of acute coronary syndrome in patients with severe carotid artery stenosis

BACKGROUND AND PURPOSE

erosion of vulnerable atherosclerotic plaques may cause life-threatening thromboembolic complications. There is indeed an urgent need to recognize a clear-cut biomarker able to identify vulnerable plaques. Here, we focused on circulating proteins belonging to the lectin pathway (LP) of complement activation.

METHODS

we analyzed mannose-binding lectin (MBL), ficolin-1, -2 and -3 (LP initiators) levels by ELISA in sera from n = 240 of an already published cohort of patients undergoing endarterectomy for severe carotid stenosis and followed-up until 18 months after surgery. Immunofluorescence followed by confocal and polarized light microscopy was used to detect LP initiator intraplaque localization. Spearman's rank test was drawn to investigate correlation between serum LP levels and circulating inflammatory proteins or intraplaque components. Survival analyses were then performed to test the predictive role of LP on long-term adverse outcome.

RESULTS

ficolins, but not MBL, correlated positively with 1) high circulating levels of inflammatory markers, including MPO, MMP-8, MMP-9, ICAM-1, osteopontin, neutrophil elastase, and; 2) immune cell intraplaque recruitment. Immunofluorescence showed ficolins in calcified plaques and ficolin-2 in cholesterol-enriched plaque regions in association with macrophages. In the multivariate survival analysis, ficolin-2 serum levels predicted a major adverse cardiovascular event during the follow-up, independently of symptomatic status and inflammatory markers (hazard ratio 38.6 [95 % CI 3.9-385.2]).

CONCLUSIONS

ficolins support intraplaque immune cell recruitment and inflammatory processes ultimately leading to plaque vulnerability. Especially for ficolin-2 a strong predictive value toward adverse cardiovascular events was demonstrated. This evidence offers potentially new pharmacological target to dampen the inflammatory mechanisms leading to plaque vulnerability.

Ultrasonographical Features Associated with Progression of Atherosclerosis in Patients with Moderate Internal Carotid Artery Stenosis

Carotid artery stenosis (CAS) is a leading cause of ischemic stroke. Plaque stabilization is a major management approach. Information about the ultrasonographical and clinical features associated with the progression of moderate internal carotid artery (ICA) stenosis (50-69%) could assist with prognostication and risk factor modifications. We evaluated 287 patients with moderate ICA stenosis (50-69%) and subsequently evaluated them at follow-up points at 12, 24, and 36 months. Patients were divided into three groups according to the degree of ICA stenosis: progression (70-99%, n = 48), stable (50-69%, n = 210), and regression (< 50%, n = 29). Responsible plaque thickness (RPT) across groups during follow-up was compared using a repeated measure ANOVA test. An ordinal regression was subsequently applied to identify risk factors for atherosclerosis progression. Male (P = 0.04), hypoechoic plaque (P < 0.01), smoking (P = 0.02), plaque ulceration (P = 0.05), and contralateral severe CAS or occlusions (P = 0.04) on ultrasound was more frequent in the progression group vs. other two groups. The ordinal regression revealed that only hypoechoic plaque (OR, 7.03; 95% CI, 3.34-14.81; P < 0.01) and contralateral ICA severe stenosis or occlusion (OR, 2.86; 95% CI, 1.41-5.80; P < 0.01) were independently associated with stenosis progression, while statin use was inversely associated with stenosis progression (OR, 0.26; 95% CI, 0.13-0.54; P < 0.01). Of note, symptomatic vs. asymptomatic moderate CAS at baseline was not associated with progression. For patients with moderate CAS, hypoechoic plaque, contralateral severe stenosis or occlusion on ultrasonography, and statin use are independently related to stenosis progression. Statin use may delay the progression of carotid stenosis.

Lectin Pathway of Complement Activation Is Associated with Vulnerability of Atherosclerotic Plaques

Inflammatory mechanisms may be involved in atherosclerotic plaque rupture. By using a novel histology-based method to quantify plaque instability here, we assess whether lectin pathway (LP) of complement activation, a major inflammation arm, could represent an index of plaque instability. Plaques from 42 consecutive patients undergoing carotid endarterectomy were stained with hematoxylin-eosin and the lipid core, cholesterol clefts, hemorrhagic content, thickness of tunica media, and intima, including or not infiltration of cellular debris and cholesterol, were determined. The presence of ficolin-1, -2, and -3 and mannose-binding lectin (MBL), LP initiators, was assessed in the plaques by immunofluorescence and in plasma by ELISA. LP activation was assessed in plasma by functional in vitro assays. Patients presenting low stenosis (≤75%) had higher hemorrhagic content than those with high stenosis (>75%), indicating increased erosion. Increased hemorrhagic content and tunica media thickness, as well as decreased lipid core and infiltrated content were associated with vulnerable plaques and therefore used to establish a plaque vulnerability score that allowed to classify patients according to plaque vulnerability. Ficolins and MBL were found both in plaques’ necrotic core and tunica media. Patients with vulnerable plaques showed decreased plasma levels and intraplaque deposition of ficolin-2. Symptomatic patients experiencing a transient ischemic attack had lower plasma levels of ficolin-1. We show that the LP initiators are present within the plaques and their circulating levels change in atherosclerotic patients. In particular, we show that decreased ficolin-2 levels are associated with rupture-prone vulnerable plaques, indicating its potential use as marker for cardiovascular risk assessment in atherosclerotic patients.

Identification of Ultrasonic Echolucent Carotid Plaques Using Discrete Fréchet Distance Between Bimodal Gamma Distributions

OBJECTIVE

Echolucent carotid plaques are associated with acute cardiovascular and cerebrovascular events (ACCEs) in atherosclerotic patients. The aim of this study was to develop a computer-aided method for identifying echolucent plaques.

METHODS

A total of 315 ultrasound images of carotid plaques (105 echo-rich, 105 intermediate, and 105 echolucent) collected from 153 patients were included in this study. A bimodal gamma distribution was proposed to model the pixel statistics in the gray scale images of plaques. The discrete Fréchet distance features (DFDFs) of each plaque were extracted based on the statistical model. The most discriminative features (MDFs) were obtained from DFDFs by the linear discriminant analysis, and a k-nearest-neighbor classifier was implemented for classification of different types of plaques.

RESULTS

The classification accuracy of the three types of plaques using MDFs can reach 77.46%. When a receiver operating characteristics curve was produced to identify echolucent plaques, the area under the curve was 0.831.

CONCLUSION

Our results indicate potential feasibility of the method for identifying echolucent plaques based on DFDFs.

SIGNIFICANCE

Our method may potentially improve the ability of noninvasive ultrasonic examination in risk prediction of ACCEs for patients with plaques.

Correlation of ABCD2 score with degree of internal carotid artery stenosis: an observational pilot study

BACKGROUND

ABCD(2) is a validated scoring system that predicts the risk of stroke after a transient ischemic attack (TIA). International guidelines suggest that patients with a low score can be investigated on an outpatient basis. The ABCD2 score, however, cannot identify which patients have significant internal carotid artery (ICA) disease, and this group of patients could benefit from rapid access carotid endarterectomy (RACE). Studies have shown that patients with significant carotid artery disease have a higher risk of neurologic events or recurrent stroke. The aim of this study was to document the range of ABCD2 scores in patients with carotid artery-related TIA, and investigate any correlation between the ABCD2 scores and ICA stenosis.

METHODS

Patients undergoing carotid duplex ultrasound scan for TIA from January 2009 to May 2010 from two vascular units were identified from the vascular database retrospectively. Clinical notes were reviewed and outcomes measures were recorded: ABCD2 scores (age, blood pressure, clinical features, diabetes, and duration) and carotid plaque morphology.

RESULTS

Ninety-seven patients with a mean age of 74 (range 56-90) years had ICA stenoses of ≥50% up to 100%. Fifty-seven patients had an ABCD2 score of ≤4. There was no significant correlation between ABCD2 scores and degree of ICA stenosis nor carotid plaque morphology (P=0.2, r=1.0, and P=1.0, r=0.0007, respectively).

CONCLUSIONS

Because no correlation between ABCD2 scores and the degree of ICA stenosis was found, all patients with carotid territory TIA should undergo urgent imaging of the carotid arteries because a high proportion of these patients may benefit from RACE.

Comparison of grey scale median (GSM) measurement in ultrasound images of human carotid plaques using two different softwares

Grey scale median (GSM) measured on ultrasound images of carotid plaques has been used for several years now in research to find the vulnerable plaque. Centres have used different software and also different methods for GSM measurement. This has resulted in a wide range of GSM values and cut-off values for the detection of the vulnerable plaque. The aim of this study was to compare the values obtained with two different softwares, using different standardization methods, for the measurement of GSM on ultrasound images of carotid human plaques. GSM was measured with Adobe Photoshop(®) and with Artery Measurement System (AMS) on duplex ultrasound images of 100 consecutive medium- to large-sized carotid plaques of the Beta-blocker Cholesterol-lowering Asymptomatic Plaque Study (BCAPS). The mean values of GSM were 35·2 ± 19·3 and 55·8 ± 22·5 for Adobe Photoshop(®) and AMS, respectively. Mean difference was 20·45 (95% CI: 19·17-21·73). Although the absolute values of GSM differed, the agreement between the two measurements was good, correlation coefficient 0·95. A chi-square test revealed a kappa value of 0·68 when studying quartiles of GSM. The intra-observer variability was 1·9% for AMS and 2·5% for Adobe Photoshop. The difference between softwares and standardization methods must be taken into consideration when comparing studies. To avoid these problems, researcher should come to a consensus regarding software and standardization method for GSM measurement on ultrasound images of plaque in the arteries.

Accuracy of a Novel Risk Index Combining Degree of Stenosis of the Carotid Artery and Plaque Surface Echogenicity

Background and Purpose—

The purpose of this study was to determine the accuracy of a risk index in symptomatic or asymptomatic carotid stenoses.

Methods—

Consecutive patients presenting 50% to 99% carotid stenoses were included. A semiautomated gray scale-based color mapping (red, yellow, and green) of the whole plaque and of its surface was achieved. Surface was defined as the region located between the lumen (Level 0) and, respectively, 0.5, 1, 1.5, and 2 mm. Risk index was based on a combination of degree of stenosis and the proportion of the red color (reflecting low echogenicity) on the surface or on the whole plaque.

Results—

There were 67 (36%) symptomatic and 117 (64%) asymptomatic carotid stenoses. Risk index values were higher among symptomatic stenoses (0.46 mean versus 0.29; P <0.0001); on receiver operating characteristic curves, risk index presented a stronger predictive power compared with degree of stenosis or surface echogenicity alone. Also, in a regression model including age, gender, degree of stenosis, surface echogenicity, gray median scale of the whole plaque, and risk index, risk index measured within the surface region located at 0.5 mm from the lumen was the only parameter significantly associated with the presence of symptoms (OR, 4.89; 95% CI, 2.7–8.7; P =0.0000002). The best criterion to differentiate between symptomatic and asymptomatic stenoses was a risk index value >0.36 (sensitivity and specificity of 78% and 65%, respectively).

Conclusions—

Risk index was significantly higher in the presence of symptoms and could therefore be a valuable tool to assess the clinical risk of a carotid plaque.