Carotid artery endarterectomy in patients with symptomatic non-stenotic carotid artery disease

Imaging of non-stenotic carotid plaque for embolic stroke of undetermined source

PURPOSE

Ischemic stroke is a significant cause of death and disability. Embolic Stroke of Undetermined Source (ESUS) accounts for a large proportion of acute ischemic strokes. A clear etiology is crucial for the treatment and prevention of stroke. The pathogenic mechanism of non-stenotic carotid plaque (NSCP) in ESUS is not yet fully understood. This study used computed tomographic angiography (CTA) to assess the correlation between NSCP and ESUS.

METHOD

Eighty-one patients with unilateral anterior circulation ESUS were retrospectively enrolled between June 2020 and June 2022. The prevalence of NSCP, degree of stenosis, plaque thickness, plaque type, plaque irregularity, plaque ulceration, focal areas of hypodensity within the plaque, and positive remodeling were evaluated in both carotid arteries on CTA. Univariate and multivariate logistic regression were used to determine the relationship between NSCP, plaque characteristics, and ipsilateral stroke.

RESULTS

Among 81 patients with unilateral anterior circulation ESUS, the incidence of NCSP was significantly higher in the ipsilateral carotid artery than in the contralateral side (76.5 % vs. 60.5 %, P = 0.028). Plaque type, plaque thickness, plaque thickness >3 mm, and focal areas of hypodensity within the plaque were remarkably different between two sides of carotid plaques (all P < 0.05). In addition, multifactorial logistic regression showed that intraplaque hypodensity (aOR = 6.449 [95 % CI, 1.818-22.878]) and greater plaque thickness (aOR = 2.476 [95 % CI, 1.14-5.38]) were significantly associated with ESUS.

CONCLUSIONS

The prevalence of NSCP ipsilateral to stroke is higher in ESUS patients, and more complex plaque features were found on the ipsilateral side. Greater plaque thickness and hypodensity within the plaque were significantly associated with ESUS, and these plaques may be an important embolization source of ESUS.

Symptomatic non-stenotic carotid disease: current challenges and opportunities for diagnosis and treatment

Symptomatic non-stenotic carotid plaques (SyNC) are an under-researched and under-recognized source of stroke. Various imaging markers of non-stenotic carotid plaques that are associated with stroke risk have been identified, but these causal relationships need to be confirmed in additional prospective studies. Currently, there exists neither a standardized SyNC definition nor a dedicated set of imaging protocols, although researchers have started to address these shortcomings. Moreover, many neuroradiologists are still unaware of the condition, and hence do not comment on high-risk plaque features other than stenosis in their reports. Regarding SyNC treatment, scant data exist as to whether and to what extent medical, interventional and surgical treatments could influence the course of the disease; the relative lack of data on the 'natural' history of untreated SyNC makes treatment comparisons difficult. In our opinion, endovascular SyNC treatment represents the most promising treatment option for SyNC, since it allows for targeted elimination of the embolic source, with few systemic side effects and without the need for general anesthesia. However, currently available carotid devices are designed to treat stenotic lesions, and thus are not optimally designed for SyNC. Developing a device specifically tailored to SyNC could be an important step towards establishing endovascular SyNC treatment in clinical practice. In this review, we provide an overview of the current state of evidence with regard to epidemiological, clinical and imaging features of SyNC, propose a SyNC definition based on imaging and clinical features, and outline a possible pathway towards evidence-based SyNC therapies, with a special focus on endovascular SyNC treatment.

MR Imaging of Carotid Artery Atherosclerosis: Updated Evidence on High-Risk Plaque Features and Emerging Trends

MR imaging is well-established as the criterion standard for carotid artery atherosclerosis imaging. The capability of MR imaging to differentiate numerous plaque components has been demonstrated, including those features that are associated with a high risk of sudden changes, thrombosis, or embolization. The field of carotid plaque MR imaging is constantly evolving, with continued insight into the imaging appearance and implications of various vulnerable plaque characteristics. This article will review the most up-to-date knowledge of these high-risk plaque features on MR imaging and will delve into 2 major emerging topics: the role of vulnerable plaques in cryptogenic strokes and the potential use of MR imaging to modify carotid endarterectomy treatment guidelines.

Dickkopf-1 promotes vascular smooth muscle cell foam cell formation and atherosclerosis development through CYP4A11/SREBP2/ABCA1

Vascular smooth muscle cells (VSMCs) are considered to be a crucial source of foam cells in atherosclerosis due to their low expression level of cholesterol exporter ATP-binding cassette transporter A1 (ABCA1) intrinsically. While the definite regulatory mechanisms are complicated and have not yet been fully elucidated, we previously reported that Dickkopf-1 (DKK1) mediates endothelial cell (EC) dysfunction, thereby aggravating atherosclerosis. However, the role of smooth muscle cell (SMC) DKK1 in atherosclerosis and foam cell formation remains unknown. In this study, we established SMC-specific DKK1-knockout (DKK1SMKO ) mice by crossbreeding DKK1flox/flox mice with TAGLN-Cre mice. Then, DKK1SMKO mice were crossed with APOE-/- mice to generate DKK1SMKO /APOE-/- mice, which exhibited milder atherosclerotic burden and fewer SMC foam cells. In vitro loss- and gain-of-function studies of DKK1 in primary human aortic smooth muscle cells (HASMCs) have proven that DKK1 prevented oxidized lipid-induced ABCA1 upregulation and cholesterol efflux and promoted SMC foam cell formation. Mechanistically, RNA-sequencing (RNA-seq) analysis of HASMCs as well as chromatin immunoprecipitation (ChIP) experiments showed that DKK1 mediates the binding of transcription factor CCAAT/enhancer-binding protein delta (C/EBPδ) to the promoter of cytochrome P450 epoxygenase 4A11 (CYP4A11) to regulate its expression. In addition, CYP4A11 as well as its metabolite 20-HETE-promoted activation of transcription factor sterol regulatory element-binding protein 2 (SREBP2) mediated the DKK1 regulation of ABCA1 in SMC. Furthermore, HET0016, the antagonist of CYP4A11, has also shown an alleviating effect on atherosclerosis. In conclusion, our results demonstrate that DKK1 promotes SMC foam cell formation during atherosclerosis via a reduction in CYP4A11-20-HETE/SREBP2-mediated ABCA1 expression.

Nonstenotic Carotid Plaques and Embolic Stroke of Undetermined Source: A Multimodality Review

Symptomatic nonstenotic carotid artery disease has been increasingly recognized as a thromboembolic source in patients who would otherwise be classified as having embolic stroke of undetermined source. Evidence suggests that certain plaque features seen on sonography, CT, and MR imaging in nonstenotic carotid artery disease may predispose to recurrent stroke in patients with embolic stroke of undetermined source. We performed a focused literature review to further study plaque features in the context of embolic stroke of undetermined source and to determine which plaque features may be associated with ipsilateral ischemic events in such patients. Plaque thickness as seen on both ultrasound and CT appears to have a consistent association with ipsilateral stroke in patients with embolic stroke of undetermined source across multiple studies. Intraplaque hemorrhage as seen on MR imaging is now understood to have a strong association with ipsilateral stroke in patients with embolic stroke of undetermined source. Continued study of various plaque features as seen on different modalities is warranted to uncover other potential associations.