Nonstenosing Plaques Research Articles

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

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. 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 >0.3cm; ulceration; length >1.0cm), soft component, or calcification identified in the CTA results. We used Fisher exact test to compare the reporting frequencies of the 5 plaque features. 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). 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.

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

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). 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. 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.

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.

Reclassification of Ischemic Stroke Etiological Subtypes on the Basis of High-Risk Nonstenosing Carotid Plaque.

Background and Purpose- Carotid artery plaque with <50% luminal stenosis may be an underappreciated stroke mechanism. We assessed how many stroke causes might be reclassified after accounting for nonstenosing plaques with high-risk features. Methods- We included patients enrolled in the Cornell Acute Stroke Academic Registry from 2011 to 2015 who had anterior circulation infarction, magnetic resonance imaging of the brain, and magnetic resonance angiography of the neck. High-risk plaque was identified by intraplaque hemorrhage ascertained from routine neck magnetic resonance angiography studies using validated methods. Infarct location was determined from diffusion-weighted imaging. Intraplaque hemorrhage and infarct location were assessed separately in a blinded fashion by a neuroradiologist. We used the McNemar test for matched data to compare the prevalence of intraplaque hemorrhage ipsilateral versus contralateral to brain infarction. We reclassified stroke subtypes by including large-artery atherosclerosis as a cause if there was intraplaque hemorrhage ipsilateral to brain infarction, regardless of the degree of stenosis. Results- Among the 1721 acute ischemic stroke patients registered in the Cornell Acute Stroke Academic Registry from 2011 to 2015, 579 were eligible for this analysis. High-risk plaque was more common ipsilateral versus contralateral to brain infarction in large-artery atherosclerotic (risk ratio [RR], 3.7 [95% CI, 2.2-6.1]), cryptogenic (RR, 2.1 [95% CI, 1.4-3.1]), and cardioembolic strokes (RR, 1.7 [95% CI, 1.1-2.4]). There were nonsignificant ipsilateral-contralateral differences in high-risk plaque among lacunar strokes (RR, 1.2 [95% CI, 0.4-3.5]) and strokes of other determined cause (RR, 1.5 [95% CI, 0.7-3.3]). After accounting for ipsilateral high-risk plaque, 88 (15.2%) patients were reclassified: 38 (22.6%) cardioembolic to multiple potential etiologies, 6 (8.5%) lacunar to multiple, 3 (15.8%) other determined cause to multiple, and 41 (20.8%) cryptogenic to large-artery atherosclerosis. Conclusions- High-risk carotid plaque was more prevalent ipsilateral to brain infarction across several ischemic stroke subtypes. Accounting for such plaques may reclassify the etiologies of up to 15% of cases in our sample.

Detection of Vulnerable Plaque in Patients with Cryptogenic Stroke.

In up to 40% of ischemic stroke cases the etiology remains unknown. A substantial proportion of these patients has non- or only mildly stenosing carotid artery plaques not fulfilling common criteria for large artery stroke, but beeing suspicious for arterio-arteriell embolism. Several imaging techniques allow the non-invasive analysis of plaque features. Nevertheless, carotid MRI might be best suited to assess the key features of vulnerable plaques. This review article discusses potential causes of cryptogenic stroke, the role of plaque imaging in non-stenosing plaques and the association of vulnerable plaques and specific plaque features with stroke risk and stroke recurrence.

Carotid and femoral ultrasound morphology screening and cardiovascular events in low risk subjects: a 10-year follow-up study (the CAFES-CAVE study )

Background: Subclinical arteriosclerotic lesions at the carotid and femoral bifurcations may be related to the occurrence of future cardiovascular events and of occult arteriosclerotic coronary disease. B-mode ultrasound of carotid and femoral arteriosclerotic bifurcation lesions may provide a simple screening method to select asymptomatic subjects at risk of future events. Methods and results: 13 221 low-risk, healthy, asymptomatic individuals were included in a 10-year, prospective, follow-up based on carotid and femoral bifurcation morphology defined by B-mode ultrasound. Four classes were considered at inclusion (I: normal wall, II: wall thickening, III: non-stenosing plaques, IV: stenosing plaques). When 10 000 subjects (75.6% of included subjects; 6055 males, 3945 females) completed the 10-year follow-up the study was concluded. At 10 years there were 10 events (out of 7989 subjects) in class I and 81 events in II (930 subjects; incidence=8.6%); 239 events were observed in class III (611 subjects; 39.28%) and 381 events (470 subjects; 81.06%) in IV; 61 deaths occurred in classes III+IV (1081 subjects) producing a death rate within these two classes of 5.5% (51 out of 61=81.5% in class IV). The increased event rates in classes III and IV were significant (log rank; P<0.02) in comparison with I and II. Conclusions: Carotid and femoral morphology identified 2011 subjects (20.1% of the population) in classes II, III, IV including 98.6% of cardiovascular events and deaths in the following 10 years. A higher ( P<0.05) rate of progression in classes III and IV in comparison with I and II was also observed. The ultrasound carotid and femoral classification was useful in selecting subjects at very low risk of cardiovascular events (class I), those at limited risk (class II) and a group at moderate risk (class III). A subpopulation at high risk of cardiovascular events (IV) was identified.

Cigarette smoking as a determinant of high-grade carotid artery stenosis in Hispanic, black, and white patients with stroke or transient ischemic attack.

We sought to investigate the association of cigarette smoking with high-grade carotid artery stenosis in Hispanic, black, and white patients with cerebral ischemia in two independent samples. Prospectively collected data from the Northern Manhattan Stroke Study (NOMASS) (n=431) and the Berlin Cerebral Ischemia Databank (BCID) (n=483) were used separately for a cross-sectional study estimating the association between cigarette smoking and high-grade carotid stenosis (defined as a luminal narrowing of > or =60%, diagnosed by duplex and/or Doppler ultrasound). In both studies, cerebral ischemia patients with normal sonographic findings or nonstenosing plaques of their carotid arteries served as a comparison group. Multivariate logistic regression models were used for statistical tests to determine the association between smoking and the dependent variable for high-grade carotid stenosis. Age, sex, hypertension, diabetes, hypercholesterolemia, and race/ethnicity were considered potential confounders. Further analyses of the NOMASS data estimated the effect of the amount of cigarette use and the impact of race/ethnicity. High-grade carotid stenoses were found in 14% of the NOMASS and in 21% of the Berlin patients. In Berlin the entire sample was white, whereas in New York only 19% of the cohort were white. In both samples, smoking was independently associated with severe carotid stenosis (NOMASS: odds ratio [OR], 1.5; 95% confidence interval [CI], 1.1 to 2.0; BCID: OR, 3.9; 95% CI, 2.4 to 6.4). Patients smoking 20 pack-years or more showed a significant association (OR, 2.0; 95% CI, 1.1 to 3.9), whereas no significant effect was found for lower amounts of cigarette use. In NOMASS, white smokers displayed a significant (OR, 3.2; 95% CI, 1.1 to 8.9) association with high-grade carotid stenosis, the association for black smokers was less strong, and no association was found among Hispanics. Smoking is an independent determinant of severe carotid artery stenosis in patients with focal cerebral ischemia. The association differs by race/ethnicity, with the greatest effect observed among whites.

Prevalence of plaques and stenoses detectable by echo-Doppler examination in the femoral arteries of an elderly population

Using echo-Doppler evaluation, we assessed the prevalence of possible atherosclerotic lesions in the common femoral arteries ( n = 478) and superficial femoral arteries ( n = 478) in 239 subjects (age range 65–94 years) living in retirement houses in Seattle. Ankle pressure was measured with a pneumatic cuff and a continuous wave Doppler. There were 68 individuals with an ankle arm index less than 0.97 and 39 of these with a index below 0.90. An echo-Doppler examination was performed with an Advanced Technologies Laboratories Mark 600 Duplex Scanner. We found 167 (34.9%) common femoral arteries affected by non-stenosing plaque while 19 arteries (4%0) had stenosis or occlusion. In addition, 178 (37.2%) superficial femoral arteries showed non-stenosing plaques. The subjects with common femoral disease were 27 (11.3%), those with evidence of superficial femoral artery disease were 48 (20.1%), and those affected by disease in both sites were 84 (35.1%). There were 80 people (33.5%) with no ultrasound evidence of femoral artery disease. We found that the presence and severity of disease increased progressively in the decades 65–74, 75–84 and 85–94. We also demonstrated a positive association between major cardiovascular risk factors and ultrasound evidence of peripheral disease. The prevalence of femoral artery disease in an apparently healthy population was relatively high, although stenoses in most instances were not severe. We conclude that non-invasive ultrasound methods identify a fraction of individuals ( n = 39, 16% of the total) with flow-reducing stenoses (ankle-arm index (AAI) < 0.90) in the peripheral circulation of the lower limbs: they are expected to be at high risk for cardiovascular death in general. Echo-Doppler might be used to monitor further disease progression and to evaluate the efficacy of different therapeutic or preventive interventions.

Prevalence of extracranial carotid artery disease detectable by echo-Doppler in an elderly population.

Little information is available on extracranial carotid artery disease in free-living elderly individuals. We sought to evaluate the prevalence of carotid lesions in the elderly. Using echo-Doppler, we assessed the prevalence of possible atherosclerotic lesions in the internal carotid arteries (n = 478) and the external and common carotid arteries (n = 956) of 239 subjects 65-94 years of age living in retirement homes in Seattle, Wash. We found that 152 (31.8%) internal carotid arteries were affected by nonstenosing plaque and 37 arteries (7.7%) had stenosis or occlusion. In addition, 193 (20.2%) external or common carotid arteries showed nonstenosing plaques. There were 128 subjects (53.6%) with internal carotid disease, 106 (44.3%) with evidence of external or common carotid disease, and 75 (31.4%) affected by disease in all three sites. There were 80 subjects (33.5%) with no ultrasound evidence of carotid disease. We found that the presence and severity of carotid disease increased between the decades 65-74 and 75-84. We also demonstrated a positive association between systolic blood pressure and ultrasound evidence of carotid disease that was independent of age. The prevalence of extracranial artery disease in an apparently healthy population was high, although stenoses in most instances were not severe. We conclude that noninvasive ultrasound methods identify a relatively small fraction of individuals (5% of the total) at high risk for stroke or transient ischemic attack. Echo-Doppler might be used to monitor further disease progression and to evaluate the efficacy of different therapeutic or preventive interventions.

B-Mode Imaging of Intraluminal Thrombus of the Internal Carotid Artery

Six patients with the diagnosis of intraluminal thrombus of the internal carotid artery are reported. In the first 2 patients with large thrombi, CW-Doppler sonography, B-mode scanning, and histological findings were in agreement The third patient had CW-Doppler and B-mode sonographical findings of a large intraluminal thrombus immediately before an embolic cerebral infarct. Three weeks later, angiography showed a plaque with only an excavation remaining. Another patient had an intraluminal thrombus superimposed on a nonstenosing plaque which was not detected by CW-Doppler sonography but could be identified during B-mode scanning. Angiography and pathoanatomy were confirmative. The fifth patient with B-mode visualization of an echolucent intraluminal structure did not show any thrombus intraoperatively. The sixth patient is reported to demonstrate the failure of B-mode imaging as well as angiography in detecting clots which were found pathoanatomically. Intraluminal thrombi as potential sources of brain embolism can be attached to atherosclerotic plaques of any degree of stenosis. Nonstenosing lesions with an attached thrombus may escape CW-Doppler sonography and even angiography but may be shown during high-resolution B-mode imaging. False-positive findings, however, cannot be avoided. Plaques with thrombi may cause strokes more frequently than assumed.

Arterial retinal circulatory disorders: an urgent indication for Doppler sonographic study of the carotid flow system

Nineteen subjects with retinal strokes of different degrees of severity (amaurosis fugax, occlusion of individual retinal arteries or of the central retinal artery) were examined by continuous-wave Doppler sonography. Evaluation of periorbital Doppler flow and direct examination of the major neck vessels were performed. Twelve subjects presented with homolateral arteriosclerotic lesions at the carotid bifurcation. The ultrasonographic findings were confirmed by carotid arteriography. High-grade stenosis or occlusion of the internal carotid artery were found in approximately 50% of the patients; the remainder turned out to have low-grade stenoses or nonstenosing plaques. These findings emphasize the role of emboli from the major neck arteries in the pathogenesis of retinal and cerebral insults. Hemodynamic effects seem to be of minor significance. Continuous-wave Doppler sonography is a completely non invasive, but nevertheless reliable method for the detection of clinically relevant carotid lesions. Especially patients suffering from retinal insults should be examined by Doppler sonography, since they are at high risk for further cerebral stroke.