Comparison of the ECST, CC, and NASCET grading methods and ultrasound for assessing carotid stenosis

We compared three angiographic methods for grading of carotid stenosis and examined the correlation between angiographic and ultrasound findings. Two observers independently measured 111 carotid stenoses on arteriographic films of 84 patients. The stenoses were graded according to the European Carotid Surgery Trial (ECST), North American Symptomatic Carotid Endarterectomy Trial (NASCET), and Common Carotid (CC) methods. The results obtained by these methods were compared, and the interobserver reproducibility of the measurements was calculated. In addition, all angiographic results were compared to ultrasound findings obtained before angiography. Measurements using the CC method were the most reproducible and those using the NASCET method the least. The NASCET method underestimated the degree of stenosis compared to the other methods. The ECST and CC methods yielded almost identical results (97% agreement). Ultrasound provided an accuracy of 94% compared to ECST and CC methods and 84% compared to the NASCET method. Interobserver reproducibility of angiographic quantification of carotid stenoses was best for the CC and ECST methods and least for the NASCET method. Ultrasound demonstrated better accuracy than the ECST and CC methods. Received: 7 April 1999/Received in revised form: 5 October 1999/Accepted: 11 April 2000     

颈动脉闭塞性疾病外科治疗发展史简

本文简单回顾了颈动脉闭塞性疾病的外科治疗历史。特别指出,自1991年北美症状性颈动脉内膜切除术试验和欧洲颈动脉外科手术试验等多中心大规模随机对照临床试验结果公布后,颈动脉内膜切除术在颈动脉粥样硬化性疾病治疗中的地位已毋庸置疑。该项外科手术技术虽然在中国起步较晚,但其发展前景良好。     

Prospective study on the complication rate of carotid surgery

BACKGROUND: Randomized trials of carotid endarterectomy for high-grade stenosis have shown a benefit for surgery under the condition of low perioperative complication rates. Concerns have been expressed that the complication rates of carotid surgery are higher in everyday practice and may vary considerably between centers. We prospectively established the complication rate for carotid surgery in a single institution. DESIGN: Prospective 2-year study. All patients received pre- and postoperative neurological evaluation. Laboratory tests included pre- and postoperative brain imaging, intracranial and neck vessel sonography, conventional angiography, magnetic resonance angiography, and intraoperative monitoring. PARTICIPANTS: 108 consecutive patients: 54 symptomatic patients fulfilling the inclusion criteria of the European Carotid Surgery Trial (ECST) and 54 asymptomatic patients fulfilling the inclusion criteria of the North American Trial on Asymptomatic Stenoses (ACAS). SETTING: Single academic center with a high volume of carotid endarterectomies (>50 per year). Participating center in ECST. MAIN OUTCOME MEASURES: Stroke or death as defined in the randomized trials. RESULTS: The overall complication rate was 8.3% (95% CI 4.1-15.6%). Complications were more frequent in patients with symptomatic stenosis (11.1%, CI 4.6-23.3%) than in asymptomatic cases (5.6%, CI 1.5-16.4%). Three patients died (2 strokes, 1 myocardial infarction). Disabling strokes were found in 2 patients (Rankin scale scores 3 and 4). Nondisabling strokes (Rankin scale score 1 and 2) occurred in 4 patients. The complication rates for symptomatic and asymptomatic patients were higher than the ones reported in the randomized trials, but 95% confidence intervals showed that the differences were not statistically significant. The point estimates of complication rates still supported a benefit of surgery for patients with symptomatic stenosis, but denied a positive effect of endarterectomy for patients with asymptomatic stenosis. CONCLUSION: In this center, a beneficial effect of carotid surgery for asymptomatic stenoses cannot be safely assumed.     

Prediction of angiographic carotid artery stenosis indexes by colour Doppler-assisted duplex imaging. A critical appraisal of the parameters used

The aim of our study was to establish colour Doppler-assisted duplex imaging (CDDI)-criteria to predict an angiographic internal carotid artery (ICA) stenosis of at least 70%, according to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trialists (ECST) methods of measurement. In the following, we describe the findings in 79 patients who were screened for carotid endarterectomy by CDDI and further evaluated by digital subtraction angiography (DSA). In 158 carotid arteries, 107 stenoses of > 30% and nine occlusions were found. Receiver operator characteristic graphs were constructed in order to calculate sensitivities and specificities of the assessment by CDDI in the prediction of high-grade stenoses determined by angiography. Optimal cut-off points were defined by highest accuracy which reflects the combination of high sensitivity and specificity. The critical index of a high-grade ICA stenosis according to the ECST method could be predicted with an accuracy greater than 90% by a systolic peak velocitiy of 1.25 m/s or an area reduction by CDDI of 70%. Corresponding values, 1.6 m/s and 80% area reduction, predicted the stenosis indexes according to the NASCET method less reliably, with accuracies of between 80% and 90%. Flow velocity criterion was slightly less accurate than the area reduction criterion by CDDI. Finally, double-blind evaluation performed by two readers per examination modality showed that the measurement of area reduction in CDDI is at least as reliable as stenosis indexes according to ECST and NASCET methods.     

Measuring carotid artery stenosis

OBJECTIVE: Five different calliper methods for assessing the degree of carotid artery stenosis and visual estimation ("eyeballing") of postmortem carotid arteriograms were compared with the planimetric gold standard of the area reduction at the site of the stenosis. METHODS: During autopsy 53 carotid specimens were removed in toto from 31 neurological patients. Carotid arteries were ligated and redistended to a physiological degree for standardised three-plane arteriography. Afterwards, the entire specimen was filled with an embedding medium under the same conditions and sectioned. Slices at the site of stenoses were histologically processed. Computerised planimetric analysis of the lumen area reduction was performed and compared with the arteriographic findings. Arteriograms were evaluated by two independent observers by means of linear Common Carotid Artery (CC), the European Carotid Surgery Trial (ECST) and the North American Symptomatic Carotid Endarterectomy Trial (NASCET), and squared measurements (NASCET2, ECST2) after applying the pi r2 function. Further, three independent observers performed eyeballing of the degree of stenosis from the postmortem arteriographies. RESULTS: Planimetry was carried out in 29 internal carotid artery (ICA) and 17 common carotid artery (CCA) stenoses ranging from 8.5 to 100%. The smallest mean differences of the degree of stenosis in % between planimetry and arteriography were -0.5 and 0.6%. The narrowest 95 %-limits of agreement covered a range of +/-24.1 and 26.3% of stenoses, and the highest correlation coefficients were both 0.9 for the CC and ECST2 techniques, respectively. By eyeballing, the degree of stenosis was underestimated by 13.5 to 15.8% on average. The narrowest limits of agreement between two observers for eyeballing covered a range of 35%. CONCLUSION: Three-plane arteriography has only a moderate accuracy and reproducibility in detecting and measuring carotid artery stenosis independent of the technique of measurement used.     

Stroke prevention by surgery for symptomatic disease in carotid territory.

The benefit of surgical procedures in preventing stroke is of concern to physicians, surgeons, and all health-care providers. The multicenter randomized trial has been applied in evaluating these strategies. Extracranial-intracranial anastomosis has failed to measure up to this rigid form of scientific scrutiny and the reasons for the demise of this procedure are reviewed. By contrast, for symptomatic disease of the internal carotid artery, patients with very severe stenosis are better treated by endarterectomy than with medical care alone. The ongoing North American Symptomatic Carotid Endarterectomy Trial (NASCET) is reviewed and the compelling reasons to continue the trial for patients with moderate disease are outlined.     

Accurate Measurement of Carotid Stenosis

The methods used for measurement of carotid artery stenosis are not uniform. Witness the chaos that developed when the North American Symptomatic Carotid Endarterectomy Trial (NASCET) group changed its classification system from area to linear measurements only to discover that the European Carotid Stenosis Trial (ECST) used still another angiographic definition of degree of stenosis so that the data from the two studies were not comparable. Fortunately, this has been reconciled by recalculation of the data. In still other studies, using unvalidated ultrasound instruments has made it difficult or impossible to compare results. In part, these problems have been the result of misdirected attempts to amalgamate concepts from Doppler and duplex ultrasound with those of arteriography. The former is more precise and accurate than the latter, yet its methodology is harder to apply and has not been generally distributed. Even such anatomical terms as “carotid bulb” are not standard. Ultrasonographers consider it to be the distal common carotid artery, to vascular surgeons it is the carotid sinus, while still others consider it to be both or neither. The present authors advocate a uniform methodology utilizing duplex ultrasound and predict that it plus magnetic resonance angiography will become the standard by which extracranial carotid artery disease is evaluated in the     

Current treatments in neurology: Stroke

There have been major advances in stroke treatment based on robust evidence from large clinical trials. This review covers both acute treatment and secondary prevention. Thrombolysis is now established as a therapy for ischaemic stroke presenting within 3 hours, and the possibility of extending the time window and refining the selection of suitable patients, is being addressed in further trials. Anticoagulants are of proven benefit in cardioembolic stroke, and particularly atrial fibrillation. For prevention of other stroke subtypes antiplatelet agents appear to have a better risk–benefit ratio. Evidence for the use of dual antiplatelet therapy, including the recent MATCH study, are discussed. Carotid endarterectomy is of proven benefit in patients with > 70% symptomatic stenosis. Recent analysis has emphasised the importance of operating as soon after symptom onset as possible. Operating on asymptomatic carotid stenosis remains controversial; even after the recent Asymptomatic Carotid Surgery Trial which showed that by operating on 32 people one disabling stroke or death could be prevented over a 5 years period.     

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.     

An audit of carotid endarterectomy for internal carotid artery disease at Dunedin Hospital

Carotid endarterectomy, mostly for symptomatic internal carotid artery stenosis, has been successfully performed in both the vascular and neurological surgery units at Dunedin Hospital. This study was performed to compare our results with those of the North American Symptomatic Carotid Endarterectomy Trial and the European Carotid Surgery Trial. The 30-day perioperative morbidity and mortality rate was 4.3% (1.2% < 95% Cl > 7.4%) which compares favourably with an estimated upper limit of 5.5% based on recent trial reports. The present study highlights the difficulty in modelling local clinical practice on results of major trials when standards of patient evaluation and surgical skill may differ from those of the large studies. To justify generalization of indications for intervention based on the multicentre trials, there must be continual monitoring of local surgical results, and standardized use of diagnostic investigations.     

Endarterectomy, best medical treatment or both for stroke prevention in patients with asymptomatic carotid artery stenosis

Carotid endarterectomy (CEA) is currently frequently performed in subjects with asymptomatic carotid artery stenosis over 70%, as clinical trials like the Asymptomatic Carotid Atherosclerosis Study and Asymptomatic Carotid Surgery Trial demonstrated a significant benefit for stroke prevention. A low risk reduction in the long-term prevention of stroke or death and the required lower than 3% of surgical risk are associated with surgery. That means that an important number of patients needs to be operated to prevent 1 stroke over 5 years (number needed to treat: 21) with an absolute risk reduction of 5.4%. It is reasonable to consider CEA for patients aged 40-75 years and with asymptomatic stenosis of 60-99%, for patients with a life expectancy of at least 5 years, and in centres with a surgical morbidity-mortality of less than 3%. Therefore, it is of interest to identify high-risk patients with asymptomatic carotid stenosis who will more likely benefit from surgery. Techniques such as ultrasound or magnetic resonance imaging may identify plaque morphology or detect clinically asymptomatic embolization. CEA combined with the best medical treatment and good management of modifiable risk factors might be superior to medical management alone or surgery in preventing stroke. There is no level I evidence to support carotid artery stenting in asymptomatic carotid stenosis even in a subgroup of patients with a high surgical risk.     

Time trends in the published risks of stroke and death due to endarterectomy for symptomatic carotid stenosis

BACKGROUND: Large randomised trials performed in the 1980s and early 1990s showed that carotid endarterectomy (CEA) is beneficial for patients with recently symptomatic severe stenosis. Some surgeons have argued that the operative risk of stroke and death has fallen over the last decade due to refinements in operative technique, and that the indications for surgery should therefore now be broadened. Yet, studies of routinely collected data report higher operative mortality than in the trials, and surgical case series without independent post-operative assessment by a neurologist may not provide reliable data on stroke risk. METHODS: We performed a systematic review of all studies published between 1994 and 2001 inclusive that which reported the risks of stroke and death for symptomatic carotid stenosis, and compared the reported risks and patient characteristics with those in the ECST and NASCET and with our previous review of studies published prior to 1995. Pooled estimates of the operative risk of stroke and death were obtained by Mantel-Haenszel meta-analysis. RESULTS: Of 383 studies published between 1994 and 2001, only 45 reported operative risks for patients with symptomatic stenosis separately. The pooled operative risk of stroke and death reported in studies published by surgeons only (4.2%, 95% CI = 2.9-5.5, 34 studies) was significantly lower (p < 0.0001) than that in the ECST and NASCET combined (7.0%, 95% CI = 6.2-8.0), whereas the pooled risk reported in studies that involved neurologists was similar (6.5%, 95% CI = 4.3-8.7, 11 studies, p = 0.6). In contrast, operative mortality in ECST and NASCET was significantly lower than in other studies published between 1994 and 2001. By comparison with our previous review, when stratified according to involvement of neurologists, we found no evidence of a reduction in published risks of death or stroke and death due to CEA between 1985 and 2001. CONCLUSIONS: There is no evidence of a systematic reduction over the last decade in the published risks of stroke and death due to CEA for symptomatic stenosis. Operative risks in studies with comparable outcome assessment are similar to ECST and NASCET. The surgical data from the large trials are still likely therefore to be applicable to routine clinical practice.     

Association between arterial bifurcation anatomy and angiographic plaque ulceration among 4,627 carotid stenoses

Stability of atheromatous plaques is influenced by local mechanical and haemodynamic factors, such as plaque motion and shear stress. However, although blood vessel anatomy is an important determinant of haemodynamics, particularly at bifurcations, there have been no previous clinical studies of the association between arterial anatomy and plaque ulceration. We therefore studied arterial anatomy and plaque ulceration using angiograms of 4,627 carotid bifurcations with atheromatous disease from the European Carotid Surgery Trial (ECST). We studied the vessel diameter and area ratios that have been shown in flow models to affect local haemodynamics and shear stress, and which are known to vary widely between and within individuals (internal to common, external to common, external to internal carotid artery and outflow/inflow area). Angiographic plaque surface morphology was defined as ulcerated or not ulcerated. To avoid any potential bias due to selective inclusion of patients in the ECST, we studied the contralateral, and usually asymptomatic, as well as the symptomatic carotid artery. To correct for the effects of systemic factors that might influence plaque stability, we also studied the relationship between the degree of asymmetry of bifurcation anatomy within individuals and the presence of plaque ulceration. Despite considerable inter-individual variation in carotid anatomy, we found no association between the prevalence of angiographic plaque ulceration and any of the anatomical parameters studied in either symptomatic or contralateral carotid arteries. There were also no associations between ipsilateral bifurcation anatomy and plaque ulceration in individuals with unilateral plaque ulceration. Carotid arterial anatomy does not appear to be an important determinant of plaque stability. Other factors that influence local haemodynamics, such as the anatomy and composition of the plaque itself may be more important.     

Treatment of carotid artery disease: Stenting or surgery?

Carotid endarterectomy (CEA) is the only form of cerebral revascularization for which Level 1 evidence of effectiveness has been reported. Recent studies demonstrate the feasibility of carotid artery stenting (CAS) as an alternative to CEA. Its popularity is due to the perceived advantages of a less invasive treatment for carotid occlusive disease. Two randomized trials have reported no difference in the composite stroke, death, and myocardial infarction rate between CAS and CEA. However, these trials were not powered to identify superiority between the two procedures. A trial sponsored by the National Institutes of Health is currently underway to make that determination. The lead-in phase of this trial noted low complication rates with CAS. These results have encouraged the US Food and Drug Administration to approve the use of CAS in patients with neurologic symptoms (ie, ipsilateral stroke, transient ischemic attacks, and amaurosis fugax) in association with severe medical co-morbidities. Patients with carotid restenosis after previous CEA, anatomically inaccessible lesions above C2, and radiation-induced stenoses may also benefit from preferential treatment with CAS. The National Institutes of Health have now expanded the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) to include asymptomatic patients, and resulting data will help to clarify the role of CAS in this subset as well.     

Medical complications associated with carotid endarterectomy. North American Symptomatic Carotid Endarterectomy Trial (NASCET)

BACKGROUND AND PURPOSE: Carotid endarterectomy (CE) has been shown to be beneficial in patients with symptomatic high-grade (70% to 99%) internal carotid artery stenosis. To achieve this benefit, complications must be kept to a minimum. Complications not associated with the procedure itself, but related to medical conditions, have received little attention. METHODS: Medical complications that occurred within 30 days after CE were recorded in 1415 patients with symptomatic stenosis (30% to 99%) of the internal carotid artery. They were compared with 1433 patients who received medical care alone. All patients were in the North American Symptomatic Carotid Endarterectomy Trial (NASCET). RESULTS: One hundred fifteen patients (8.1%) had 142 medical complications: 14 (1%) myocardial infarctions, 101 (7.1%) other cardiovascular disorders, 11 (0.8%) respiratory complications, 6 (0.4%) transient confusions, and 10 (0.7%) other complications. Of the 142 complications, 69.7% were of short duration, and only 26.8% prolonged hospitalization. Five patients died: 3 from myocardial infarction and 2 suddenly. Medically treated patients experienced similar complications with one third the frequency. Endarterectomy was approximately 1.5 times more likely to trigger medical complications in patients with a history of myocardial infarction, angina, or hypertension (P<0.05). CONCLUSIONS: Perioperative medical complications were observed in slightly fewer than 1 of every 10 patients who underwent CE. The majority of these complications completely resolved. Most complications were cardiovascular and occurred in patients with 1 or more cardiovascular risk factors. In this selected population, the occurrence of perioperative myocardial infarction was uncommon.     

Carotid Artery Stenosis: Medical Therapy,Surgery, and Stenting

Purpose of Review

The purpose of the study was to update the recent information pertaining to carotid artery stenosis risk stratification and treatment.

Recent Findings

Current decision-making related to carotid artery stenosis is based on clinical trials that are outdated. Medical therapy has improved considerably in the past two decades, and this has reduced the stroke rate for both symptomatic and asymptomatic carotid stenoses. In recent community-based studies, the stroke risk with asymptomatic stenosis has been < 1% per year. For asymptomatic carotid stenosis, new trials such as CREST 2 and ECST 2 will determine whether revascularization has any benefit beyond aggressive medical management. For symptomatic patients, carotid endarterectomy is associated with a lower periprocedural stroke rate compared to carotid stenting. Age greater than 70 years is also associated with an increased risk for carotid stenting patients.

Summary

Clinicians should consider a variety of clinical and radiologic variables in reaching treatment decisions for patients with carotid stenosis. Both symptomatic and asymptomatic patients should receive optimal medical therapy.

     

Carotid artery stenting: Current status and plans for an NIH-sponsored clinical trial

Clinical efficacy of carotid artery stenting (CAS) has not yet been confirmed by randomized clinical trial methodology. Although carotid endarterectomy (CEA) is considered the “gold standard” in the management of patients with asymptomatic and symptomatic extracranial carotid occlusive disease, comparisons between CAS and CEA are now underway. In the United States, the CREST (Carotid Revascularization Endarterectomy Versus Stent Trial) protocol is now completing credentialing cases as randomization of cases proceeds at several institutions. This trial, supported by the National Institute of Neurological Disorders and Strokes (NINDS), National Institutes of Health, will contribute to clinical decisions regarding the use of these 2 procedures in patients at high risk for stroke.     

颈动脉支架成形术与药物治疗颈动脉狭窄的对比研究

目的 分析颈动脉支架成形术（CAS）与药物治疗颈动脉狭窄的疗效，并评价其安全性。方法 2003年11月至2006年3月采用颈动脉支架成形术治疗颈内动脉狭窄（狭窄率≥50％）21例,于围手术期进行抗血小板治疗及控制危险因素。单纯药物治疗组53例，药物治疗方案同治疗组。临床随访6～28个月。结果 21例手术操作完全成功，术后残余狭窄＜30％，术中3例患者出现一过性心率减慢、血压下降，2例出现颈内动脉远端血管痉挛，治疗后好转；术后未发生新的卒中，颈动脉超声未显示再狭窄。药物治疗组随访期间，5例患者再发卒中，颈动脉超声检查发现14例患者狭窄程度加重，其中2例血管造影证实颈内动脉完全闭塞。结论 与药物治疗组比较，CAS治疗颈内动脉狭窄可以提高患者的生活质量，而且比较安全，短期疗效较好，但有待大样本研究结果证实     

Endarterectomy vs. Angioplasty in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) Trial

Endarterectomy versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) is a French multicenter, non-inferiority randomized trial with national research organisation funding. In brief, patients are eligible if they have experienced a carotid TIA or non-disabling stroke within 4 months before randomisation and if they have an atherosclerotic stenosis of the region of the ipsilateral carotid bifurcation of 60% or more, as determined by the NASCET method, that investigators believe is suitable for both carotid surgery and angio-plasty. Carotid surgery is performed using standard operative techniques. Carotid angioplasty consists of pri-mary stenting with cerebral protection. The primary end-points are: (a) any stroke or death within 30 days of the procedure and (b) any stroke or death within 30 days of the procedure plus ipsilateral stroke. To join the study, a centre must form a multidisciplinary team, including avascular neurologist, a vascular surgeon and an interventionalist. Operator experience must be substantiated through documentation of a sufficient number of cases performed.     

High rate of restenosis after carotid artery stenting in patients with high-grade internal carotid artery stenosis

OBJECTIVE: Carotid endarterectomy (CEA) is the gold-standard procedure for the majority of patients with high-grade symptomatic internal carotid artery stenosis and also for specified high-grade asymptomatic stenoses; however, a proportion of patients are treated with carotid endovascular therapy. We aimed to document medium-term clinical and neurosonographical outcome after carotid artery stenting (CAS). METHODS: 53 patients (mean age: 65 +/- 8 years) with high-grade (> or = 70 % by means of duplex sonography) carotid artery stenosis were enrolled into the study. Nineteen patients had asymptomatic, 34 patients had symptomatic stenoses. All patients had a pre-interventional CT, Doppler and duplex sonography, and digital subtraction angiography (DSA) or magnetic resonance angiography (MRA) prior to the procedural DSA. All patients were offered CEA as the gold-standard procedure and as an alternative to CAS. Both clinical and Duplex sonographical follow-up was obtained at day 1 and 7, month 1, month 3, month 6, month 12, and every subsequent 6 months after the procedure. Mean follow-up time was 22 +/- 1.6 months (+/- SEM). RESULTS: 2/53 patients suffered from stroke. A further 2 patients suffered from carotid artery occlusion shortly after CAS. The cumulative rate of restenosis during follow-up was 24.5 % (13/53). Four of these (7.5 %) were of high-grade and led to further interventional or surgical therapy. CONCLUSIONS: A high rate of restenosis was found during follow-up after CAS. Our analysis of non-selected patients emphasizes that CEA remains the gold-standard procedure for the treatment of symptomatic internal carotid artery stenosis. The frequently performed endovascular treatment of carotid stenosis outside the setting of a randomized controlled trial is not supported by our data.