Associations Between Features of Nonstenosing Carotid Plaque on Computed Tomographic Angiography and Ischemic Stroke Subtypes

Prevalence of non-stenotic vulnerable carotid plaques in embolic stroke of undetermined source

INTRODUCTION

The latest research in ischaemic stroke pathogenesis is directed to unveil what is inside embolic stroke of undetermined source (ESUS). Whether vulnerable non stenotic carotid plaques (NSTEPS), i.e. atherosclerotic lesions in carotid arteries determining a stenosis lower than 50%, may represent a cause of stroke in ESUS is a matter of debate. We aimed to study the prevalence of NSTEPS in an ESUS population.

PATIENTS AND METHODS

We retrospectively identified a consecutive ESUS population admitted to the Stroke-Unit of Careggi Hospital, Italy from 2019 to 2022. Characteristics of atherosclerotic plaques (thickness, ulceration, hypodensity) and their location (ipsilateral versus contralateral to the stroke) were studied on carotid CT angiography (CTA). Follow-up data were recorded up to 24 months after stroke.

RESULTS

We identified 57 ESUS patients with unilateral ischaemic lesions studied with CTA; 53 (93%) had an ipsilateral carotid plaque, 81% contralateral, (p = 0.754) and 74% both. Plaques ipsilateral to stroke were ≥ 3 mm thick in 15 (28%) patients; hypodense in 14 (26%) and ulcerated in 5 (9%). The frequency of hypodensity was higher in ipsilateral compared to contralateral plaques (26% vs. 13%, p = 0.039) and ulceration was around four times more frequent, although not statistically significant (9% vs. 2%, p = 0.219). At follow-up, six patients had stroke recurrence (11%), 2 of them were in the same vascular territory of the former.

DISCUSSION AND CONCLUSIONS

Our data suggest that plaques ipsilateral to stroke seem to be more frequently vulnerable and consequently more prone to embolization. Prospective data are needed to clarify the causal role of NSTEPS in ESUS.

Nonstenotic carotid artery plaques on computed tomography angiography in embolic stroke of undetermined source

This study aims to evaluate the role of <50% stenotic cervical carotid artery plaques in embolic stroke of undetermined source (ESUS), focusing on plaque characteristics in symptomatic versus asymptomatic carotid arteries (contralateral). In this cross-sectional observational study, 81 patients who met the diagnostic criteria for ESUS and underwent were retrospectively analyzed. Carotid plaques causing <50% stenosis were examined, noting features such as plaque thickness, degree of luminal stenosis, irregularity, ulceration, calcification, and hypodensity. These characteristics were compared between the ipsilateral and contralateral carotid arteries. The study involved 33 men and 48 women, with plaques ≥3mm thick significantly more common in the ipsilateral carotid arteries (P < .05). Notable features such as plaque ulceration, irregularity, noncalcified plaque, and hypodensity were significantly more frequent ipsilaterally (P < .05). Of the plaque patients, 54.3% (44/81) were on the ipsilateral side, compared to 29.6% (24/81) on the contralateral side (P = .0024). Our findings underscore the potential significance of non-stenotic carotid plaques in ESUS. These plaques, especially those with certain high-risk characteristics, are more prevalent ipsilaterally and should be considered in clinical evaluations and treatment of ESUS.

Explainable machine-learning model to classify culprit calcified carotid plaque in embolic stroke of undetermined source

Background

Embolic stroke of undetermined source (ESUS) may be associated with carotid artery plaques with <50% stenosis. Plaque vulnerability is multifactorial, possibly related to intraplaque hemorrhage (IPH), lipid-rich-necrotic-core (LRNC), perivascular adipose tissue (PVAT), and calcification morphology. Machine-learning (ML) approaches in plaque classification are increasingly popular but often limited in clinical interpretability by black-box nature. We apply an explainable ML approach, using noncalcified plaque components and calcification features with SHapley Additive exPlanations (SHAP) framework to classify calcified carotid plaques as culprit/non-culprit.

Methods

In this retrospective cross-sectional study, patients with unilateral anterior circulation ESUS who underwent neck CT angiography and had calcific carotid plaque were analyzed. Calcification-level features were derived from manual segmentations. Plaque-level features were assessed by a neuroradiologist blinded to stroke-side and by semi-automated software. Calcifications/plaques were classified as culprit if ipsilateral to stroke-side. Eight baseline ML models were compared. Three CatBoost models were trained: Plaque-level, Calcification-level, and Combined. SHAP was incorporated to explain model decisions.

Results

70 patients yielded 116 calcific carotid plaques (60 ipsilateral to stroke; 270 calcifications (146 ipsilateral)). 17 plaque-level and 15 calcification-level features were extracted. Baseline CatBoost model outperformed other models. Combined model achieved test AUC 0.77 (95% CI: 0.59-0.92), accuracy 0.82 (95% CI: 0.71 - 0.91), mean cross-validation AUC 0.78. Plaque-level and calcification-level models performed lower (AUC 0.41 95% CI: 0.15-0.68, 0.60 95% CI 0.44-0.76). Combined model utilized five features: plaque thickness, IPH/LRNC volume ratio, PVAT volume, calcification minimum density, and total calcification volume over mean density ratio. Plaque thickness was most important feature based on SHAP values, with potential threshold at >2.6 mm.

Conclusions

ML model trained with noncalcified plaque and calcification features can classify culprit calcific carotid plaque with greater accuracy than models trained using only plaque-level or calcification-level features. Model using clinically interpretable features with SHAP framework provides explanations for its decisions and allows identification of potential thresholds for high-risk features.

The role of non-stenosing carotid artery plaques in embolic stroke of undetermined source, is it a silent offender? A review of literature

PURPOSE

Atherosclerotic cervical internal carotid artery disease is one of the major causes of ischemic stroke and transient ischemic attacks. The risk of stroke from mild to moderate stenoses (i.e. <50% stenosis) might be underestimated. There is increasing evidence that plaque morphological features reflect plaque instability that may harbor high risk for embolization. In this narrative review, we will review the literature on plaque features that predict vulnerability beyond the degree of stenosis, discuss the clinical association with stroke, and evaluate the evidence that these lesions serve as a source for embolic stroke of unknown source (ESUS).

METHODS

We performed a literature search using PubMed, EMBASE, and Web of Science. The terms "embolic stroke of undetermined source" and "plaque morphology" were used either alone or in combination with "non-flow limiting stenosis," "non-stenosing plaques," "high-risk plaque features" or "internal carotid artery plaque." Data on plaque morphology and ESUS were mainly taken from review articles, observational studies including retrospective cohort and cross-sectional studies, meta-analyses, and systematic reviews.

CONCLUSION

Nonstenosing carotid artery plaques with high-risk features carry a remarkable risk for stroke occurrence and randomized clinical trials are warranted for further evaluation of using carotid artery stenting or carotid endarterectomy to mitigate the risk of stroke.

High-Risk Plaque Features in the Non-stenosing Carotid Artery, How Frequently is This Reported? A Retrospective Study

Background

High-risk features of non-stenosing (ie, <50%) carotid plaques are emerging as a possible source of embolism in patients with embolic stroke of undetermined source (ESUS). However, in the absence of hemodynamically significant stenosis, neuroradiology reports rarely describe these morphological features. Our aim was to determine how often high-risk features of non-stenosing plaques are included in diagnostic imaging reports.

Methods

In this retrospective study, we evaluated computed tomography angiography (CTA) reports associated with the CTA imaging results for a previously published cohort study. Plaque features reporting frequencies were calculated and defined as the number of times specific plaque features were included in the CTA reports (Thickness, ulceration, length, soft component and calcification) divided by the number of occurrences of high-risk plaque features (Thickness >0.3 cm; ulceration; length >1.0 cm), soft component, or calcification identified in the CTA results. We used Fisher exact test to compare the reporting frequencies of the 5 plaque features.

Results

We analyzed 152 CTA reports. The frequency of reporting plaque thickness (0/40; 0%), ulceration (3/37; 8.1%), and length (7/29; 24.1%) was significantly lower than the reporting of plaque calcification (122/122; 100%) and presence of soft component (31/34; 72.1%) when these features were present in CTA imaging results (all P < 0.001).

Conclusion

When carotid plaques are not causing hemodynamically significant stenosis, neuroradiology reports frequency mention plaque density but often exclude other characteristics. Neuroradiologists and neurologists should collaborate to create algorithms, scoring systems and prediction models to accurately determine which plaque features are highly associated with embolism.

Identification of vulnerable carotid plaque with CT-based radiomics nomogram

AIM

To develop and validate a radiomics nomogram for identifying high-risk carotid plaques on computed tomography (CT) angiography (CTA).

MATERIALS AND METHODS

A total of 280 patients with symptomatic (n=131) and asymptomatic (n=139) carotid plaques were divided into a training set (n=135), validation set (n=58), and external test set (n=87). Radiomic features were extracted from CTA images. A radiomics model was constructed based on selected features and a radiomics score (rad-score) was calculated. A clinical factor model was constructed by demographics and CT findings. A radiomics nomogram combining independent clinical factors and the rad-score was constructed. The diagnostic performance of three models was evaluated and validated by region of characteristic curves.

RESULTS

Calcification and maximum plaque thickness were the independent clinical factors. Twenty-four features were used to build the radiomics signature. In the validation set, the nomogram (area under the curve [AUC], 0.977; 95% CI, 0.899-0.999) performed better (p=0.017 and p=0.031) than the clinical factor model (AUC, 0.862; 95% CI, 0.746-0.938) and radiomics signature (AUC, 0.944; 95% CI, 0.850-0.987). In external test set, the nomogram (AUC, 0.952; 95% CI, 0.884-0.987) and radiomics signature (AUC, 0.932; 95% CI, 0.857-0.975) showed better discrimination capability (p=0.002 and p=0.037) than clinical factor model (AUC, 0.818; 95% CI, 0.721-0.892).

CONCLUSION

The CT-based nomogram showed satisfactory performance in identification of high-risk plaques in carotid arteries, and it may serve as a potential non-invasive tool to identify carotid plaque vulnerability and risk stratification.

Extracranial Carotid Plaque Calcification and Cerebrovascular Ischemia: A Systematic Review and Meta-Analysis

BACKGROUND

Although coronary calcification quantification is an established approach for cardiovascular risk assessment, the value of quantifying carotid calcification is less clear. As a result, we performed a systematic review and meta-analysis to evaluate the association between extracranial carotid artery plaque calcification burden and ipsilateral cerebrovascular ischemic events.

METHODS

A comprehensive literature search was performed in the following databases: Ovid MEDLINE(R) 1946 to July 6, 2022; OVID Embase 1974 to July 6, 2022; and The Cochrane Library (Wiley). We performed meta-analyses including studies in which investigators performed a computed tomography assessment of calcification volume, percentage, or other total calcium burden summarizable in a single continuous imaging biomarker and determined the association of these features with the occurrence of ipsilateral stroke or transient ischemic attack.

RESULTS

Our overall meta-analysis consisted of 2239 carotid arteries and 9 studies. The presence of calcification in carotid arteries ipsilateral to ischemic stroke or in stroke patients compared with asymptomatic patients did not demonstrate a significant association with ischemic cerebrovascular events (relative risk of 0.75 [95% CI, 0.44-1.28]; P=0.29). When restricted to studies of significant carotid artery stenosis (>50%), the presence of calcification was associated with a reduced risk of ischemic stroke (relative risk of 0.56 [95% CI, 0.38-0.85]; P=0.006). When the analysis was limited to studies of patients with mainly nonstenotic plaques, there was an increased relative risk of ipsilateral ischemic stroke of 1.72 ([95% CI, 1.01-2.91]; P=0.04). Subgroup meta-analyses of total calcium burden and morphological features of calcium showed wide variability in their strength of association with ischemic stroke and demonstrated significant heterogeneity.

CONCLUSIONS

The presence of calcification in carotid plaque confers a reduced association with ipsilateral ischemic events, although these results seem to be limited among carotid arteries with higher degrees of stenosis. Adoption of carotid calcification measures in clinical decision-making will require additional studies providing more reproducible and standardized methods of calcium characterization and testing these imaging strategies in prospective studies.

Computed tomography angiography-based radiomics model to identify high-risk carotid plaques

Background

Extracranial atherosclerosis is one of the major causes of stroke. Carotid computed tomography angiography (CTA) is a widely used imaging modality that allows detailed assessments of plaque characteristics. This study aimed to develop and test radiomics models of carotid plaques and perivascular adipose tissue (PVAT) to distinguish symptomatic from asymptomatic plaques and compare the diagnostic value between radiomics models and traditional CTA model.

Methods

A total of 144 patients with carotid plaques were divided into symptomatic and asymptomatic groups. The traditional CTA model was built by the traditional radiological features of carotid plaques measured on CTA images which were screened by univariate analysis and multivariable logistic regression. We extracted and screened radiomics features from carotid plaques and PVAT. Then, a support vector machine was used for building plaque and PVAT radiomics models, as well as a combined model using traditional CTA features and radiomics features. The diagnostic value between radiomics models and traditional CTA model was compared in identifying symptomatic carotid plaques by Delong method.

Results

The area under curve (AUC) values of traditional CTA model were 0.624 and 0.624 for the training and validation groups, respectively. The plaque radiomics model and PVAT radiomics model achieved AUC values of 0.766, 0.740 and 0.759, 0.618 in the two groups, respectively. Meanwhile, the combined model of plaque and PVAT radiomics features and traditional CTA features had AUC values of 0.883 and 0.840 for the training and validation groups, respectively, and the receiver operating characteristic curves of combined model were significantly better than those of traditional CTA model in the training group (P<0.001) and validation group (P=0.029).

Conclusions

The combined model of the radiomics features of carotid plaques and PVAT and the traditional CTA features significantly contributes to identifying high-risk carotid plaques compared with traditional CTA model.

A Short Review on Advances in Early Diagnosis and Treatment of Ischemic Stroke

Ischemic stroke is a leading cause of morbidity and mortality worldwide, necessitating advancements in early diagnosis and treatment modalities. This review aims to provide an overview of recent advances in the early diagnosis and treatment of ischemic stroke, highlighting the importance of the potential impact on patient outcomes. Recent advancements have focused on various aspects of stroke care, including imaging techniques, laboratory testing, telemedicine and mobile technology, intravenous thrombolysis, mechanical thrombectomy, and collaborative systems. Advances in imaging techniques have played a pivotal role in the early diagnosis of ischemic stroke. Computed tomography perfusion imaging, advanced magnetic resonance imaging (MRI) techniques, multimodal imaging, and automated image processing tools have greatly improved the ability to assess the extent of ischemic injury. Laboratory testing has seen significant progress in identifying biomarkers associated with ischemic stroke. High-sensitivity cardiac troponin assays have improved our understanding of the cardiac component of stroke. Additionally, biomarkers such as S100B, glial fibrillary acidic protein, and neuron-specific enolase have shown promise in assessing stroke severity and prognosis. Mobile applications and wearable devices facilitate stroke symptom recognition, risk assessment, and prompt medical attention. The development of tenecteplase, a modified form of tissue plasminogen activator, has enhanced clot-dissolving efficacy. Collaborative systems, including regional stroke systems of care and telestroke networks, have optimized communication and coordination among healthcare providers. Interoperable electronic health records streamline information exchange and facilitate prompt decision-making. Mobile communication technologies enhance real-time collaboration, involving all stakeholders in stroke care. Future directions focus on artificial intelligence and machine learning algorithms for stroke diagnosis and risk assessment. Wearable devices and remote monitoring may enable continuous monitoring of stroke-related indicators. Overall, advances in early diagnosis and treatment of ischemic stroke can enhance stroke care, reduce treatment delays, and improve patient outcomes.

Association Between Spotty Calcification in Nonstenosing Extracranial Carotid Artery Plaque and Ipsilateral Ischemic Stroke

Background Small spotty calcifications in the coronary arteries are associated with an increased risk of myocardial infarction. We examined the association between spotty calcifications near the carotid bifurcations and ipsilateral ischemic stroke in patients with <50% luminal stenosis of the extracranial carotid arteries. Methods and Results We used data from the CAESAR (Cornell Acute Stroke Academic Registry), a prospective registry of all patients with acute ischemic stroke admitted to our institution. We included patients who met criteria for cryptogenic stroke and underwent computed tomography angiography and brain magnetic resonance imaging. Patients with extracranial carotid artery stenosis ≥50% and patients with posterior or bilateral anterior circulation infarcts were excluded. We examined the carotid bifurcations for spotty calcifications, defined as ≥1 contiguous regions of luminal calcification ≤3 mm along the long axis of the vessel. We also measured low-density plaque and maximum plaque thickness. The eligible cohort consisted of 117 patients with a mean age of 66.7±1.65 years with a median National Institute of Health Stroke Scale stroke at the time of arrival of 6 (range, 3-13). The number of spotty calcifications present within a low-density plaque was significantly associated with ipsilateral infarction (0.3±0.8 versus 0.1±0.4, P=0.02). Maximum plaque thickness was also significantly associated with ipsilateral infarction (1.4 mm ±1.5 versus 1.0 mm ±1.1, P=0.004). Conclusions Spotty calcifications associated with low-density plaque and maximum plaque thickness were associated with ipsilateral ischemic stroke in patients with nonstenotic carotid atherosclerosis, suggesting a role as imaging markers of high-risk plaque.

Non-stenosing carotid artery plaques in embolic stroke of undetermined source: a retrospective analysis

BACKGROUND

We aim to identify the association between high-risk carotid plaques and their laterality to stroke in ESUS patient population. We also discuss recurrent stroke events and their laterality to the index stroke.

METHODS

This was a retrospective study. We reviewed data for patients with ESUS between June 20, 2016, and June 20, 2021. Using computed tomography angiography, we analyzed plaque features that are associated with ESUS, and then, we identified the recurrent stroke events and characterized lateralization to the index stroke.

RESULTS

Out of 1779 patients with cryptogenic ischemic stroke, we included 152 patients who met the criteria for ESUS. High-risk plaque features were found more often ipsilateral to the stroke side when compared contralaterally: plaque ulceration (19.08% vs 5.26%, p < .0001), plaque thickness > 3 mm (19.08% vs 7.24%, p = 0.001), and plaque length > 1 cm (13.16% vs 5.92%, p = 0.0218). There was also a significant difference in plaque component in which both components (soft and calcified) and only soft plaques were more prevalent ipsilaterally (42.76% vs 23.68% and 17.76% vs 9.21%, respectively, p < .0001). Of the 152 patients, 17 patients were found to have a recurrent stroke event, and 47% (n = 8) had an ipsilateral stroke to the index event. Moreover, stroke was bilateral in 41% of the patients (n = 7), and contralateral in 12% (n = 2).

CONCLUSION

High-risk plaque features studied here were more prevalent ipsilaterally to the stroke side in ESUS than contralaterally. Multicenter studies are needed to form precise prediction models and scoring systems to help guide treatment, i.e., choice of medical therapy and/or revascularization.

Prevalence of Symptomatic Nonstenotic Carotid Disease Using Simultaneous Non-Contrast Angiography and Intraplaque Hemorrhage Imaging for MR Screen Protocol

Background: To determine the prevalence of symptomatic nonstenotic carotid disease (SyNC) using simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) imaging for patients with acute stroke as an MR screen protocol and to assess imaging findings of carotid plaques. Patients and Methods: From May 2020 to October 2021, 2459 patients with suspected acute neurological symptoms were evaluated with brain diffusion-weighted imaging (DWI) and carotid SNAP imaging. We analyzed the degree of stenosis and intraplaque hemorrhage (IPH) using SNAP imaging. Prevalence of SyNC and risk factors for stroke in patients with SyNC were determined. We performed subgroup multivariate analysis between SyNC and other etiologies of stroke (non-SyNC). Results: Of 4608 carotid arteries in 2304 patients enrolled in this study, 454 (9.9%) plaques (both lesions in 128 patients) were found on SNAP imaging. Of these plaques, 353 (77.8%) showed stenosis of <50%. Of plaques with <50% stenosis, 47 (13.3%) patients had a territorial acute focal infarction. Seventeen (36.2%) were classified with embolic stroke of undetermined source (ESUS) and SyNC. High maximal wall thickness and carotid IPH were identified as influencing factors for SyNC. Conclusion: For patients with <50% stenosis and territorial infarction, SyNC is a relatively important source of stroke. Especially, high maximal wall thickness and carotid IPH are important risk factors for SyNC.

The role of cross-sectional imaging of the extracranial and intracranial vasculature in embolic stroke of undetermined source

Despite an extensive workup, nearly one third of ischemic strokes are defined as Embolic Stroke of Undetermined Source (ESUS), indicating that no clear etiologic cause has been identified. Since large vessel atherosclerotic disease is a major cause of ischemic stroke, we focus on imaging of large vessel atherosclerosis to identify further sources of potential emboli which may be contributing to ESUS. For a stroke to be considered ESUS, both the extracranial and intracranial vessels must have <50% stenosis. Given the recent paradigm shift in our understanding of the role of plaque vulnerability in ischemic stroke risk, we evaluate the role of imaging specific high-risk extracranial plaque features in non-stenosing plaque and their potential contributions to ESUS. Further, intracranial vessel-wall MR is another potential tool to identify non-stenosing atherosclerotic plaques which may also contribute to ESUS. In this review, we discuss the role of cross-sectional imaging of the extracranial and intracranial arteries and how imaging may potentially uncover high risk plaque features which may be contributing to ischemic strokes.

Characteristics of non-stenotic carotid plaque in embolic stroke of undetermined source compared with cardiogenic embolism: a retrospective cross-sectional observational study

Background

Non-stenotic carotid plaque is considered an important etiology of embolic stroke of undetermined source (ESUS). However, only a few previous studies included a negative control group, and the characteristics of non-stenotic carotid plaque in ESUS have yet to be investigated. The objective of this study is to explore the clinical characteristics of ESUS and the correlation between non-stenotic carotid plaque and ESUS.

Methods

This is a single-center, retrospective cross-sectional observational study conducted to compare differences in clinical information among ESUS, CE, and large-artery atherosclerosis (LAA), as well as the prevalence of non-stenotic carotid plaque and non-stenotic carotid plaque with low echo between patients with ESUS and CE in Changzhou No.2 People’s Hospital from January 2020 to January 2022. Ultrasound was used to evaluate the characteristics of non-stenotic carotid plaque and vulnerable carotid plaque was defined as plaque with low echo. The binary logistic regression model was used to analyze the relationship between the characteristics of non-stenotic carotid plaque and ESUS. The receiver-operating characteristic curve was used to evaluate the diagnostic efficiency of the characteristics of non-stenotic carotid plaque for ESUS.

Results

We had a final studying population of 280 patients including 81 with ESUS, 37 with CE, and 162 with LAA. There were no differences in clinical features between ESUS and LAA, but in the comparison of CE and ESUS, there were differences in age, smoking, hypertension, levels of triglyceride, total cholesterol, and low density lipoprotein cholesterol. In ESUS, the prevalence of non-stenotic carotid plaque was more common on the ipsilateral side of stroke than in CE [55 (67.90%) vs. 18 (48.65%), p = 0.046], so was the prevalence of non-stenotic carotid plaque with low echo [38 (46.91%) vs. 5 (13.51%), p < 0.001]. Logistic regression analysis showed that the prevalence of non-stenotic carotid plaque (OR: 4.19; 95% CI: 1.45–12.11; p = 0.008) and the prevalence of non-stenotic carotid plaque with low echo (OR: 5.12; 95% CI: 1.55–16.93; p = 0.007) were, respectively, the independent predictors of ESUS. The results receiver-operating characteristic (ROC) curve showed that the combination of age, hypertension, and ipsilateral non-stenotic carotid plaque with low echo had the best diagnostic efficiency for ESUS (0.811; 95%CI: 0.727–0.896; p < 0.001).

Conclusion

Our results suggest that ipsilateral vulnerable non-stenotic carotid plaque is associated with ESUS in anterior circulation infarction.

Nonstenotic Carotid Plaques in Ischemic Stroke: Analysis of the STRATIS Registry

BACKGROUND AND PURPOSE

Few studies assess nonstenotic carotid plaques on CTA, and the causative role of these plaques in stroke is not entirely clear. We used CTA to determine the prevalence of nonstenotic carotid plaques (<50%), plaque features, and their association with ipsilateral strokes in patients with cardioembolic and cryptogenic strokes.

MATERIALS AND METHODS

Data were from the Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke (STRATIS) registry, a prospective, nonrandomized registry of patients undergoing thrombectomy with the Solitaire device. The prevalence of nonstenotic carotid plaques ipsilateral and contralateral to the stroke was compared in patients with cryptogenic and cardioembolic strokes. Plaque features were further compared within both subgroups between patients with and without ipsilateral stroke. Adjusted associations among nonstenotic carotid plaque, plaque characteristics, and ipsilateral stroke in both subgroups were determined with logistic regression.

RESULTS

Of the 946 patients in the data base, 226 patients with cardioembolic stroke (median age, 72 years) and 141 patients with cryptogenic stroke (median age, 69 years) were included in the analysis. The prevalence of nonstenotic carotid plaque in the cardioembolic and cryptogenic subgroups was 33/226 (14.6%) and 32/141 (22.7%), respectively. Bilateral nonstenotic carotid plaques were seen in 10/226 (4.4%) patients with cardioembolic and 13/141 (9.2%) with cryptogenic strokes. Nonstenotic carotid plaques were significantly associated with ipsilateral strokes in the cardioembolic stroke (adjusted OR = 1.91; 95% CI, 1.15-3.18) and the cryptogenic stroke (adjusted OR = 1.69; 95% CI, 1.05-2.73) groups. Plaque irregularity, hypodensity, and per-millimeter increase in plaque thickness were significantly associated with ipsilateral stroke in the cryptogenic subgroup.

CONCLUSIONS

Nonstenotic carotid plaques were significantly associated with ipsilateral stroke in cardioembolic and cryptogenic stroke groups, and there was an association of plaque irregularity and hypodense plaque with ipsilateral stroke in the cryptogenic group, suggesting these plaques could be a potential cause of stroke in these patient subgroups.

Association between carotid artery perivascular fat density and cerebral small vessel disease

Studies aiming to identify the significance of the carotid artery perivascular fat density are limited. The present study investigated the distribution pattern of pericarotid fat and its association with imaging markers of cerebral small vessel disease (CSVD). In total, 572 subjects who underwent both neck computed tomography angiography and cranial magnetic resonance imaging were analyzed. The pericarotid fat density near the origin of the internal carotid artery (ICA) and imaging markers of CSVD, such as lacunes, white matter hyperintensities (WMHs) and dilated perivascular spaces (PVSs), were assessed. We found that an increased pericarotid fat density was associated with the presence of lacunes and a higher WMH grade in all subjects, but in the patients with acute ischemic stroke, there was a difference only among the WMH grades. There was no significant difference in the pericarotid fat density in different grades of PVSs. The patients with acute ischemic stroke had a significantly higher mean pericarotid fat density than those without stroke. In conclusion, our study provides evidence suggesting that an increased pericarotid fat density is associated with the presence and degree of WMHs and lacunes. Our findings suggested that features that appear to extend beyond the vessel lumen of the ICA may be linked to CSVD.

Sex Differences in Carotid Plaque Composition in Patients With Embolic Stroke of Undetermined Source

Background

We examined sex differences in nonstenotic carotid plaque composition in patients with embolic stroke of undetermined source (ESUS).

Methods and Results

Patients with anterior circulation ischemic stroke imaged with neck computed tomographic angiography who met criteria for ESUS or had atrial fibrillation were identified. Patients with atrial fibrillation were included as a negative control. Semiautomated plaque quantification software analyzed carotid artery bifurcations. Plaque subcomponent (calcium, intraplaque hemorrhage [IPH], and lipid rich necrotic core) volumes were compared by sex and in paired analyses of plaque ipsilateral versus contralateral to stroke. Multivariate linear regressions tested for associations. Ninety‐four patients with ESUS (55% women) and 95 patients with atrial fibrillation (47% women) were identified. Men with ESUS showed significantly higher volumes of calcified plaque (63.9 versus 19.6 mm³, P<0.001), IPH (9.4 versus 3.3 mm³, P=0.008) and a IPH/lipid rich necrotic core ratio (0.17 versus 0.07, P=0.03) in carotid plaque ipsilateral to stroke side than women. The atrial fibrillation cohort showed no significant sex differences in plaque volumes ipsilateral to stroke. Multivariate analyses of the ESUS cohort showed male sex was associated with IPH_ipsi (β=0.49; 95% CI, 0.11–0.87) and calcium_ipsi (β=0.78; 95% CI, 0.33–1.23). Paired plaque analyses in men with ESUS showed significantly higher calcified plaque (63.9 versus 34.1 mm³, P=0.03) and a trend of higher IPH_ipsi (9.4 versus 7.5 mm³, P=0.73) and lipid rich necrotic core_ipsi (59.0 versus 48.4 mm³, P=0.94) volumes.

Conclusions

Sex differences in carotid plaque composition in ESUS suggest the possibility of a differential contribution of nonstenosing carotid plaque as a stroke mechanism in men versus women.

Nonstenotic Carotid Plaque in Embolic Stroke of Undetermined Source: Interplay of Arterial and Atrial Disease

BACKGROUND AND PURPOSE

Approximately one-sixth of all ischemic strokes are attributable to embolic stroke of undetermined source (ESUS). Recent analyses suggest that atrial cardiopathy and nonstenotic carotid plaque (nsCP) may represent 2 distinct underlying causes in patients with ESUS, although both diseases share common risk factors and are pathophysiologically intertwined. In this study, we, therefore, aimed to search for associations between nsCP and markers of atrial remodeling and function in patients with embolic stroke.

METHODS

Sixty-eight patients with ESUS or atrial fibrillation (AF)-related stroke proven by imaging who underwent comprehensive echocardiographic studies, including measurements of left atrial function and remodeling, were considered. Patients with ESUS underwent a follow-up of at least 1 year after index stroke. For 20 patients with ESUS, NT-proBNP (N-terminal pro-B-type natriuretic peptide) values were available. Presence of nsCP was evaluated considering Duplex sonography and computed tomography angiography and was further categorized in possibly or probably symptomatic nsCP.

RESULTS

ESUS patients with nsCP tended to have higher values of septal and lateral total atrial conduction times (P=0.071 and P=0.072, respectively), left atrial volume index (P=0.077), and revealed significantly higher strain rates during early diastole (P=0.013) as well as higher NT-proBNP values (P=0.010) than ESUS patients without nsCP. Moreover, septal total atrial conduction time was significantly longer in ESUS patients with possibly symptomatic nsCP compared with those without (P=0.015). Comparison of ESUS with AF patients revealed significantly higher proportions of nsCP (P=0.010), possibly symptomatic nsCP (P=0.037), and probably symptomatic nsCP (P=0.036) in patients with atrial fibrillation-related stroke. In the regression analysis adjusted for vascular risk factors probably symptomatic nsCP remained significantly associated with AF (P=0.048, odds ratio: 4.46 [95% CI, 1.02-19.56]).

CONCLUSIONS

Presence of nsCP is associated with AF and markers of left atrial disease in patients with embolic stroke. Therefore, a thorough evaluation regarding atrial cardiopathy and AF in patients with ESUS should not be restricted if nsCP are found, even if high-risk plaque characteristics are evident.

Ipsilateral Nonstenotic Carotid Disease in Minor Ischemic Stroke: an Exploratory Analysis of The POINT Randomized Clinical Trial

BACKGROUND AND AIM

Ipsilateral nonstenotic carotid disease is increasingly recognized as an etiology of ischemic stroke, however tailored treatment strategies are lacking. We aimed to examine clinical characteristics and treatment effects in patients with minor ischemic stroke associated with ipsilateral nonstenotic carotid disease in the Platelet Oriented Inhibition in New TIA and Minor Ischemic Stroke (POINT) trial.

METHODS

We performed an exploratory analysis of the interaction of the treatment effects of aspirin plus clopidogrel versus aspirin monotherapy, stratified by presence of ipsilateral nonstenotic carotid disease in patients with minor ischemic stroke in the POINT trial.

RESULTS

For this exploratory analysis, 167 patients presenting with ischemic stroke and ipsilateral nonstenotic carotid disease, defined as 1%-49% carotid stenosis ipsilateral to the corresponding territory of ischemic stroke, and 833 patients no carotid disease were included. Compared to patients with no carotid disease, patients with ipsilateral nonstenotic carotid disease were older (68.5 ± 11.3 years versus 61.3 ± 12.8 years; P < 0.001), and had a higher prevalence of hypertension (76.6% versus 59.2%, P < 0.001), ischemic heart disease (13.8% versus 5.4%, P < 0.001), and tobacco use (past: 34.1% versus 25.2%, P = 0.005; present: 27.5% versus 22.8%, P = 0.005). 5.4% of patients with ipsilateral nonstenotic carotid disease had recurrent ischemic stroke within 14 days. Patients receiving dual antiplatelet therapy had a numerical reduction in recurrent ischemic stroke compared to patients receiving aspirin monotherapy, however the exploratory analysis was underpowered to detect a statistically significant difference in treatment effect (HR 0.50, 95% CI 0.18-1.40, P = 0.19).

CONCLUSION

Patients with minor ischemic stroke and ipsilateral nonstenotic carotid disease had a high risk of early stroke recurrence in the POINT trial. Dual antiplatelet therapy provided a non-statistically significant reduction in recurrent ischemic stroke with no difference in safety outcomes compared to aspirin monotherapy. Further study is needed to determine if early and short duration dual antiplatelet therapy is beneficial for all patients with ipsilateral nonstenotic carotid disease.

Associations Between Features of Nonstenosing Carotid Plaque on Computed Tomographic Angiography and Ischemic Stroke Subtypes

Background

Thromboembolism from nonstenosing carotid plaques may be an underrecognized cause of embolic strokes of undetermined source (ESUS). We evaluated the association between features of nonstenosing atherosclerotic plaque on computed tomographic angiography and ESUS.

Methods and Results

We identified consecutive acute ischemic stroke patients from 2011 to 2015 who had unilateral anterior territory infarction on brain magnetic resonance imaging and a neck computed tomographic angiography. We included ESUS cases and as controls, cardioembolic strokes. Patients with ≥50% internal carotid artery atherosclerotic stenosis ipsilateral to the stroke were excluded from this analysis. Reviewers blinded to infarct location and stroke cause retrospectively evaluated computed tomographic angiography studies for specific plaque features including thickness of the total, soft, and calcified plaque; presence of ulceration; and perivascular fat attenuation. Paired t tests and McNemar's test for paired data were used to compare plaque features ipsilateral versus contralateral to the side of infarction. Ninety‐one patients with ESUS or cardioembolic stroke were included in this study. Total plaque thickness was greater on the infarcted side (2.1±2.0 mm) than the contralateral side (1.2±1.5 mm) (P=0.006) among ESUS cases, but not among cardioembolic cases (1.9±1.6 mm versus 1.8±1.6 mm) (P=0.32).

Conclusions

Among ESUS cases, total plaque thickness was greater ipsilateral to the side of infarction than on the contralateral, stroke‐free side. No such side‐to‐side differences were apparent in cardioembolic strokes. Our findings suggest that nonstenosing large‐artery atherosclerotic plaques represent one underlying mechanism of ESUS.