North American Symptomatic Endarterectomy Trial Research Articles

The Relationship of Carotid Artery Plaque and Stenosis with Microemboli

Objective: Microembolic signals (MES) are markers that can be detected by Transcranial Doppler Ultrasonography (TCD) and are risk factors for stroke. The aim of our study is to explore the relationship between the number of MES and the extent of carotid stenosis as well as plaque morphology. Our goal is to provide a fresh perspective on the treatment of carotid stenosis. Materials and Methods: A total of 95 patients, who were admitted to the emergency department of Sultan 2.Abdülhamid Han Training and Research Hospital and were hospitalized with a diagnosis of stroke, were enrolled in the study. Patients with high-risk cardiac diseases were excluded from the study. Detailed medical histories, risk factors, and current medical treatments of the patients were documented, and microemboli detection was conducted using Transcranial Doppler (TCD). The number of microemboli in TCD was obtained by averaging the results of 2 consecutive half-hour follow-ups in a region. Carotid stenosis rates of the patients were determined by computed tomography angiography (CTA) according to the North American Symptomatic Endarterectomy Trial (NASCET) classification, and the plaque morphology was determined according to the Gray-Weale scale of carotid ultrasonography. Patients were categorized into symptomatic and asymptomatic carotid stenosis groups, and the number of microembolic signals (MES) was compared between these groups. Result: MES numbers of 95 patients with symptomatic carotid stenosis; while MES was not detected in 47.4% (n=45); 35.8% (n=34) had 1-2 MES, 8.4% (n=8) had 3-4 MES and 8.4% (n=8) 5 or more MES were detected. The relationship between the MES obtained and carotid stenosis was statistically significant (p<0.001). According to the type of plaque; while there is no MES in 68.2% (n=15) of Type-4 symptomatic stenosis, this rate is only 15% (n=3) in Type-1 stenosis. In addition, 20% (n=4) of Type-1 symptomatic stenosis had MES between 3-4 and 30% (n=6) of 5 or more MES. According to these results, the relationship between plaque type and the presence of MES is statistically significant. (p<0.001) Similar results were obtained in asymptomatic carotid stenosis. Conclusion: TCD is an easy-to-apply, non-invasive imaging technique, and MES detectable by TCD are risk factors for stroke. The relationship between MES and carotid stenosis rate and plaque type heterogeneity is statistically significant.

Invited commentary

The North American Symptomatic Carotid Endarterectomy Trial (NASCET) concluded that carotid surgery for symptomatic stenosis is better than medical therapy, and the conferred benefit of surgery is proportional to the degree of stenosis.1North American Symptomatic Endarterectomy Trial CollaboratorsBeneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis.N Engl J Med. 1991; 325: 445-453Crossref PubMed Scopus (7865) Google Scholar The European Carotid Surgery Trial (ECST) came to a similar conclusion and that “on average, the immediate risk of surgery was worth trading off against the long-term risk of stroke without surgery when the stenosis was greater than 80% diameter.”2European Carotid Surgery Trialists Collaborative GroupRandomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST).Lancet. 1998; 351: 1379-1387Abstract Full Text Full Text PDF PubMed Scopus (2966) Google Scholar The preceding and other studies leave little room for doubt that endarterectomy is beneficial to symptomatic patients; what is still being debated is the exact timing of surgery. Most clinicians agree that patients presenting with crescendo transient ischemic attacks or a mobile plaque on imaging deserve to be considered for an emergent endarterectomy to prevent a severe stroke. What is not clear is what type of patient ought to have an urgent (ie, during the same hospitalization and as promptly as possible) carotid endarterectomy. Avgerinos et al attempt to answer the question, When is it optimal to perform endarterectomy for symptomatic patients? They queried the Vascular Study Group of New England database of 14,864 carotid endarterectomies and identified 4076 performed for symptomatic stenosis. Of the latter cases, 989 carotid endarterectomies were performed within a month of symptom onset. They analyzed outcomes based on timing of surgery: same day, <48 hours, 2-5 days, and >6 days. They found that the postoperative stroke rate was highest if surgery was performed <48 hours after presenting stroke or transient ischemic attack, whereas postoperative stroke rates were similar in the other time frames. In a similar analysis from a single center and spanning the same time period, Tsantilas et al found a combined stroke and mortality rate for symptomatic patients of 2.5% and no significant difference in stroke rates in the various time periods of 48 hours, 3-7 days, 8-14 days, and 15-180 days.3Tsantilas P. Kuhnl A. Kallmeyer M. Pelisek J. Poppert H. Schmid S. et al.A short time interval between the neurologic index event and carotid endarterectomy is not a risk factor for carotid surgery.J Vasc Surg. 2017; 65: 12-20Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar Other authors have strongly emphasized the need for prompt carotid endarterectomy, provided symptoms are stable, to prevent a recurrent stroke.4Bond R. Rerkasem K. Rothwell P.M. Systematic review of the risks of carotid endarterectomy in relation to the clinical indication for and timing of surgery.Stroke. 2003; 34: 2290-2303Crossref PubMed Scopus (246) Google Scholar In performing an urgent carotid endarterectomy, there are many factors that need to be taken into consideration. By the time the surgeon sees the consult, proper imaging is obtained, and the patient is prepared for surgery, several hours would have passed. Adding to the complexity, a patient admitted on a Friday or Saturday may experience longer delays. This paper concludes that there is no major penalty in waiting a few days. Until we have more sophisticated imaging capabilities to detect which plaques are likely to disintegrate and cause recurrent symptoms, it is a guessing game.5Rothwell P.M. Prediction and prevention of stroke in patients with symptomatic carotid stenosis: the high-risk period and the high-risk patient.Eur J Vasc Endovasc Surg. 2008; 35: 255-263Abstract Full Text Full Text PDF PubMed Scopus (49) Google Scholar The prudent approach, though, is to avoid delays in removing the offending plaque. The opinions or views expressed in this commentary are those of the authors and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery. Early carotid endarterectomy performed 2 to 5 days after the onset of neurologic symptoms leads to comparable results to carotid endarterectomy performed at later time pointsJournal of Vascular SurgeryVol. 66Issue 6PreviewTiming of carotid endarterectomy (CEA) after onset of neurologic symptoms remains controversial. We assessed the association of CEA timing with postoperative outcomes. Full-Text PDF Open Archive

Differences in Plaque Morphology and Correlation of Stenosis at the Carotid Artery Bifurcation and the Carotid Siphon

The purpose of this study was to compare the type of plaque and the degree of stenosis in the carotid artery bifurcation and the carotid siphon to explore potential correlations between these parameters. A total of 119 patients (87 men, 32 women; mean age, 69 years) were retrospectively studied using MDCT angiography. Component types of the carotid artery bifurcation and the carotid siphon plaque were defined according to attenuation values, and the volumes of each plaque component were calculated. The degree of stenosis was calculated according to the North American Symptomatic Endarterectomy Trial method. Data were compared using the Wilcoxon signed-rank test, Spearman correlation analysis, and receiver operating characteristic (ROC) analysis. The results of the Wilcoxon test showed a statistically significant difference (p = 0.0001) between the degree of stenosis at the carotid artery bifurcation and that at the carotid siphon. We observed a statistically significant difference (p = 0.0001) between the total volumes of the carotid artery bifurcation (mean value, 748 mm(3)) and the carotid siphon (mean value, 54 mm(3)) plaque. Moreover, the respective mean percentages of calcified, mixed, and lipid components of plaque were 17%, 56%, and 27% in the carotid artery bifurcation and 73%, 19%, and 8% in the carotid siphon, showing a statistically significant difference (p = 0.001). ROC analysis did not show association between carotid siphon plaque volume and previous cerebrovascular events (Az = 0.562; p = 0.149), whereas the total volume of the carotid artery bifurcation plaque--and, in particular, the volume of the lipid components--showed a statistically significant association (Az = 0.691, and Az = 0.758; p < 0.001). No significant association was found between presence of mixed and fatty components of plaque in the carotid artery bifurcation and presence of similar components in the carotid siphon. The carotid artery bifurcation total plaque volume (and, in particular, carotid artery bifurcation lipid volume) was associated with previous cerebrovascular events, whereas no association with the volume of carotid siphon plaque (and its subcomponents) was found.

Assessment of carotid stenosis using three‐dimensional T2‐weighted dark blood imaging: Initial experience

To evaluate the use of a T2-weighted SPACE sequence (T2w-SPACE) to assess carotid stenosis via several methods and compare its performance with contrast-enhanced magnetic resonance angiography (ceMRA). Fifteen patients with carotid atherosclerosis underwent dark blood (DB)-MRI using a 3D turbo spin echo with variable flip angles sequence (T2w-SPACE) and ceMRA. Images were coregistered and evaluated by two observers. Comparisons were made for luminal diameter, luminal area, degree of luminal stenosis (NASCET: North American Symptomatic Endarterectomy Trial; ECST: European Carotid Surgery Trial, and area stenosis), and vessel wall area. Degree of NASCET stenosis was clinically classified as mild (<50%), moderate (50%-69%), or severe (>69%). Excellent agreement was seen between ceMRA and T2w-SPACE and between observers for assessment of lumen diameter, lumen area, vessel wall area, and degree of NASCET stenosis (r > 0.80, P < 0.001). ECST stenosis was consistently higher than NASCET stenosis (48 ± 14% vs. 24 ± 22%, P < 0.001). Area stenosis (72 ± 2%) was significantly higher (P < 0.001) than both ESCT and NASCET stenosis. DB-MRI of carotid arteries using T2w-SPACE is clinically feasible. It provides accurate measurements of lumen size and degree of stenosis in comparison with ceMRA and offers a more reproducible measure of ECST stenosis than ceMRA.

Carotid Stenting in the Elderly

Elderly patients are at higher risk of procedural complications. Surgical revascularization has been performed successfully in selected octogenarians.1,2 Nevertheless, it is widely believed that percutaneous approaches are safer in the elderly. Indeed, percutaneous coronary intervention is now successfully being performed even in selected nonagenarians.3 Thus, it is tempting to presume that carotid revascularization in the elderly might be safer if done via endovascular means (Figure).4 Figure. Angiography before (A) and after (B) a right carotid artery stent in an 81-year-old man with amaurosis fugax. Article see p 2343 The data to date, however, have been conflicting, with several reports demonstrating very high rates of stroke or death with carotid stenting in octogenarians. Furthermore, although carotid stenting with embolic protection has been shown to be noninferior to carotid endarterectomy in patients at high surgical risk, whether carotid stenting is equivalent to carotid endarterectomy remains an open question in patients at low surgical risk.5–7 Additionally, especially for asymptomatic patients, the question arises whether a patient will live long enough to derive potential benefit from any procedure. This question becomes more pressing as the elderly population expands and the definition of elderly creeps upward, and also as clinical trials continue to underenroll the elderly. The cut point where appropriate clinical caution turns instead into preconceived notions and age-related bias is difficult to define. In this issue of Circulation , Chiam et al report on 142 consecutive patients aged 80 years or older who underwent carotid stenting.8 This series of patients has previously been reported, with the current article adding observations related to intermediate-term …

“Internal cross-clamping” for symptomatic internal carotid artery thrombus

Both carotid endarterectomy and carotid artery stent placement with filter embolic protection present a higher risk for patients with internal carotid artery (ICA) lesions containing intraluminal thrombus. Despite the risk associated with intervention, patients with symptomatic intraluminal thrombus who were enrolled in the North American Symptomatic Endarterectomy Trial did better with surgical than medical treatment. We describe the novel use of an endovascular "internal cross-clamping" technique in two patients with symptomatic intraluminal thrombus in the ICA. A 57-year-old woman presented with a history of multiple episodes of left upper-extremity numbness, mild dysarthria, and agraphia occurring over the previous 24 hours. Cranial magnetic resonance imaging revealed a scattered watershed infarction of the right hemisphere and a critical stenosis of the right ICA. An 81-year-old man awoke with hemiplegia and inability to follow commands after undergoing a complicated carotid endarterectomy. Computed tomographic perfusion imaging demonstrated an increased time to peak in the left middle cerebral territory, and emergent angiography demonstrated both intimal flaps and thrombus in the endarterectomy bed. The lesions in both patients were treated with endovascular stent placement using both proximal and distal flow occlusion--a functional "internal cross-clamping"--for embolic protection. To our knowledge, this is the first report of internal trapping and stent placement for symptomatic carotid stenosis containing intraluminal thrombus. This treatment strategy should be added to the armamentarium of endovascular surgeons in selected patients with symptomatic carotid intraluminal thrombus.

“Internal cross-clamping” for symptomatic internal carotid artery thrombus

✓Both carotid endarterectomy and carotid artery stent placement with filter embolic protection present a higher risk for patients with internal carotid artery (ICA) lesions containing intraluminal thrombus. Despite the risk associated with intervention, patients with symptomatic intraluminal thrombus who were enrolled in the North American Symptomatic Endarterectomy Trial did better with surgical than medical treatment. We describe the novel use of an endovascular “internal cross-clamping” technique in two patients with symptomatic intraluminal thrombus in the ICA. A 57-year-old woman presented with a history of multiple episodes of left upper-extremity numbness, mild dysarthria, and agraphia occurring over the previous 24 hours. Cranial magnetic resonance imaging revealed a scattered watershed infarction of the right hemisphere and a critical stenosis of the right ICA. An 81-year-old man awoke with hemiplegia and inability to follow commands after undergoing a complicated carotid endarterectomy. Computed tomographic perfusion imaging demonstrated an increased time to peak in the left middle cerebral territory, and emergent angiography demonstrated both intimal flaps and thrombus in the endarterectomy bed. The lesions in both patients were treated with endovascular stent placement using both proximal and distal flow occlusion—a functional “internal cross-clamping”—for embolic protection. To our knowledge, this is the first report of internal trapping and stent placement for symptomatic carotid stenosis containing intraluminal thrombus. This treatment strategy should be added to the armamentarium of endovascular surgeons in selected patients with symptomatic carotid intraluminal thrombus.

Efficacy of patient selection strategies for carotid endarterectomy by contrast-enhanced MRA on a 1 T machine and duplex ultrasound in a regional hospital

To investigate whether contrast-enhanced magnetic resonance angiography (CE-MRA) and duplex ultrasound (DUS) could replace digital subtraction angiography (DSA) for diagnosing internal carotid artery (ICA) stenosis in regional centres with less specialized technicians and equipment, such as a 1 Tesla MRI machine. Sixty-six consecutive, symptomatic patients with ICA stenosis, as evidenced using DSA, were included. In the first 34 patients DUS was validated and cut-off criteria were established. Data were analysed by receiver operating characteristic curve and logistic regression. Two observers analysed the DUS and CE-MRA results of 32 patients. Stenoses were categorized in accordance with North American Symptomatic Endarterectomy Trial (NASCET) measurement criteria. Peak systolic velocity (PSV) in the ICA was defined as a better parameter for defining stenosis than end diastolic velocity and the PSV ICA:common carotid artery ratio. The optimal PSV threshold was 230cm/s. Four ICAs were not interpretable on DUS, and one on CE-MRA. Two patients did not undergo CE-MRA. The sensitivities and specificities were calculated: for DUS these were 100% and 68% respectively; for observer 1 on CE-MRA these were 93% and 89%, respectively; for observer 2 these were 92% and 87%, respectively. The sensitivity and specificity for combined DUS/CE-MRA were 100% and 85%, respectively. Seventy-eight percent of CE-MRA and DUS correlated. The weighted Kappa for CE-MRA and DSA were 0.8 and 0.9, respectively. DUS and CE-MRA are effective non-invasive methods for selecting patients with ICA stenosis for carotid endarterectomy in non-specialized centres using a 1T machine. The present results suggest that no referrals to more specialized centres for non-invasive diagnostic work-up for carotid artery stenoses will be necessary.

The Stent-Supported Percutaneous Angioplasty of the Carotid Artery vs. Endarterectomy Trial

The Stent-Supported Percutaneous Angioplasty of the Carotid Artery versus Endarterectomy (SPACE) Trial is investigating if both treatment modalities are equivalent in the treatment of severe symptomatic carotid stenoses. Patients with symptomatic (transient ischaemic attack or minor stroke) stenosis (above 50% following the North American Symptomatic Endarterectomy Trial criteria) eligible for both methods can be recruited into this trial. The primary endpoint is the incidence of an ipsilateral stroke or death between randomisation and day 30 after treatment. Surgeons as well as the interventionalists have to demonstrate their expertise prior to participation in the trial. Funding is mostly by public institutions (Federal Ministry of Education and Research and German Research Foundation). An external monitoring is applied. Thirty-two centres are currently taking part in the SPACE Trial that has been running in Germany, Austria and Switzerland for 3 years, and they have been able to recruit a total of around 670 patients. The definitive results of this study cannot be expected before 3–5 years.

Virtual intra-arterial angioscopy (VIA) of the carotid artery based on helical CT data.

The purpose of this study was to visualize both the vessel wall and atherosclerotic plaques in virtual intra-arterial angioscopy (VIA) based on helical CT data sets. To achieve this in vitro, the optimal reconstruction threshold of the vessel wall was determined to be 56.4% of the maximum enhancement. Using this threshold, 20 patients suffering from symptomatic carotid disease were examined in a helical CT scanner. The degree of stenosis was defined using the North American Symptomatic Endarterectomy Trial (NASCET) criteria and compared with results from digital substraction angiography (DSA). Grading of stenoses was only possible by adding the separately computed plaque geometry to the geometry of the vessel wall in a second step. Correlation between VIA and DSA in low grade, medium grade and high grade stenosis was 88%, 93% and 71%, respectively. Complete occlusions were diagnosed correctly in all patients. Sensitivity and specificity for the correct diagnosis of high grade stenosis was 93.7% and 91.3%, respectively. A realistic depiction of intraluminal structures in carotid arteries can only be generated by displaying both the vessel wall and plaque structures simultaneously.

Mehrvolumen-MR-Angiographie der A. carotis interna: Eine präoperative Vergleichsstudie

With the introduction of MR angiography (MRA) into clinical routine, arteriosclerotic lesions of the supraaortic vessels may be well demonstrated. The comparison between Multislab MRA (gradient echo, TOF) and X-ray angiography (XRA) as reference in 70 patients suspicious of stenotic lesions in the internal carotid artery proved the high reliability of these methods. In determining the degree of stenosis, according to the NASCET study (North American Symptomatic Endarterectomy Trial), a correlation between MRA and XRA of 92.3% could be calculated. The principal problem of MRA is the overestimation of high-grade stenoses; we observed 5 false-positive results in severe stenosis. Sensitivity and specificity were 95.6 and 92.6%, respectively, for detection of severe (> 60%) stenosis. Despite its limitations, MRA is a clinically important noninvasive technique for preoperative evaluation of patients undergoing carotid endarterectomy.