Comparison of color-flow Doppler scanning, power Doppler scanning, and frequency shift for assessment of carotid artery stenosis

OBJECTIVE: We investigated the accuracy of color-flow Doppler (CD) scanning, power Doppler (PD) scanning, and peak systolic Doppler frequency shift (PSF) in assessment of carotid artery stenosis with angiography used as gold standard, including the measurement techniques used in the North American Symptomatic Carotid Surgery Trial (NASCET) and the European Carotid Surgery Trial (ECST). METHODS: Fifty-eight consecutive patients diagnosed for carotid artery surgery underwent color-coded duplex sonography and angiography. The duplex examination included the assessment of PSF and the videotaping of sagittal images in CD and PD mode from the proximal common carotid artery to the distal internal carotid artery. Two experienced examiners performed the studies, but once one examiner had done the taping, the other examiner was allowed only to review the tape. Separately, each examiner reviewed the tapes and determined by cursor settings each stenosis according to NASCET and ECST. For interobserver agreement kappa statistic was used. To compare with angiography (degree of stenosis 40%, 50%, 60%, 70%, and 80%) sensitivity, specificity, positive and negative predictive values, and overall accuracy were calculated. PSF cut-off frequencies were based on receiver operator curve analysis. RESULTS: Because interobserver agreement in CD and PD was good (chance-corrected kappa > 0.6), further analysis used the between-observer mean value for each stenosis. With the NASCET measurement technique, accuracy of Doppler techniques to distinguish a 50% stenosis was 89% for PSF, 91% for CD, and 93% for PD; for a 70% stenosis it was 83% for PSF, 84% for CD, and 81% for PD. With the ECST measurement technique, accuracy to distinguish a 70% stenosis was 86% for PSF, 88% for CD, and 86% for PD; for an 80% stenosis it was 87% for PSF, 87% for CD, and 77% for PD. CONCLUSION: CD and PD carotid artery stenosis measurements are highly reproducible, and in our hands provided accuracy equal to PSF.     

Carotid artery stenting: to be or not to be?

Carotid endarterectomy (CEA) has been the standard of care for suitable patients with symptomatic or asymptomatic high grade carotid stenosis since the landmark NASCET (North American Symptomatic Carotid Endarterectomy Trial), ECST (European Carotid Surgery Trial) and ACAS (Asymptomatic Carotid Artery Surgery) studies performed in the 1990s and more recently the ACST (Asymptomatic Carotid Surgery Trial). Carotid artery stenting (CAS) in the treatment of both symptomatic and asymptomatic patients with high grade carotid stenosis has recently been investigated as an alternative to CEA. We present a review of the most recent CAS trials and examine some of the controversies that surround them.     

Carotid endarterectomy before and after publication of randomized controlled trials

BACKGROUND: In 1991, the European Carotid Surgery Trial (ECST) and the North American Symptomatic Carotid Endarterectomy Trial (NASCET) demonstrated that carotid endarterectomy (CEA), in addition to best medical therapy, significantly reduces ipsilateral stroke in patients with high-grade (70 per cent or more) carotid artery stenosis compared with best medical therapy alone. In 1995, the Asymptomatic Carotid Atherosclerosis Study demonstrated that CEA was of benefit in asymptomatic patients with stenosis greater than 60 per cent. The aim of this paper was to examine how the practice and outcome of CEA have changed since publication of these data. METHODS: A prospectively gathered computerized database comprising 634 consecutive CEAs was studied. Two time intervals were analysed: 1975-1991 inclusive (17 years) and 1 January 1992 to 1 May 1998 (6 years 4 months). RESULTS: Since 1991, there has been a fourfold increase in the number of CEAs performed annually for symptomatic disease. CEA is now performed almost exclusively for high-grade (more than 70 per cent) stenosis. There has been a significant reduction in the total peri-operative neurological event rate (12.5 versus 5.9 per cent, P < 0.05), and the 30-day combined major stroke (Rankin grade 3-5) and mortality rate has fallen to 2.0 per cent. The number of patients who have CEA for asymptomatic disease remains small with 16 of 30 being randomized within the Asymptomatic Carotid Surgery Trial. CONCLUSION: Publication of ECST and NASCET data has been associated with a major increase in the number of CEAs performed for symptomatic disease in this unit. Despite a greater proportion of high-risk patients, the results have improved progressively.     

Overview of the principal results and secondary analyses from the European and North American randomised trials of endarterectomy for symptomatic carotid stenosis.

OBJECTIVES: Review of the primary results and secondary analyses from the European Carotid Surgery Trial (ECST) and the North American Symptomatic Carotid Endarterectomy Trial (NASCET). DESIGN: Review of 48 ECST and NASCET papers. RESULTS: The simple assumption that all patients with a symptomatic stenosis >70% benefit from CEA is untenable. Approximately 70-75% will not have a stroke if treated medically. The ECST and NASCET have identified subgroups that should have expedited investigation and surgery (male sex, age >75 years, 90-99% stenosis, irregular plaque, hemispheric symptoms, recurrent events for >6 months, contralateral occlusion, multiple co-morbidity). Accordingly development of local protocols for patient selection/exclusion should involve surgeons and physicians and take account of the local operative risk. The ECST and NASCET have also shown that the ubiquitous "string sign" is not associated with a high risk of stroke, and emergency CEA is unnecessary. CONCLUSIONS: Surgeons must quote their own results and be aware that a high operative risk reduces long-term benefit. Accordingly, in those centres with a higher operative death/stroke rate, some "lower risk" patients should probably be considered for best medical therapy alone. It is hoped that pooling of the ECST and NASCET databases will enable more definitive guidelines to be developed regarding who benefits most from CEA.     

Accuracy of angiography and Doppler ultrasonography in the detection of carotid stenosis: a histopathological study of 123 cases

Summary Background. A prospective study was performed comparing the accuracy of digital subtraction angiography (DSA) and Doppler ultrasonography (DUS) stenosis findings with measurements on histological specimens. Method. DSA and DUS were used to evaluate carotid stenosis and were compared with measurements on histological specimens. Intact carotid plaques from 123 cases were removed in one piece during surgery. The specimens were histologically processed and examined in transverse sections. The smallest inner and correlating outer diameters were measured and the extent of stenosis was calculated. Carotid artery stenoses were compared and statistics done. Specimens in symptomatic cases were divided into 3 groups: stenosis 30–49% (Group 1), stenosis 50–69% (Group 2) and stenosis 70–99% (Group 3). Specimens in asymptomatic cases were divided into two groups: stenosis ≤59% (Group A) and stenosis ≥60% (Group B). Findings. Wilcoxon paired tests revealed significant differences between DSA, DUS and measurements on histological specimens. In severe stenoses only, no significant difference was observed between stenosis measurement according to the European Carotid Surgery Trial (ECST) angiography methodology and measurements on histological specimens. The most pronounced differences were found between angiography methodology of the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and measurements on histological specimens. When investigating how often preoperative measurement classified stenosis into the same Group of stenoses as postoperative measurement, DUS was the most accurate diagnostic tool. Conclusions. This study confirmed our previous results, i.e., angiography underestimates the degree of carotid artery stenosis. DUS seems to be more accurate in classifying stenoses into different groups to the extent of narrowing of the carotid arteries. These results make the position of angiography in diagnostic algorithm of carotid stenoses investigations even more questionable.     

Can the NASCET technique for measuring carotid stenosis be reliably applied outside the trial?

Purpose: The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Artery Study (ACAS) both confirmed the effectiveness of carotid endarterectomy for preventing stroke in patients who have significant carotid stenosis. A uniform technique for measuring carotid stenosis from an arteriogram (% stenosis = [1 - minimum residual lumen/normal distal cervical internal carotid artery diameter] × 100) was used in both trials, with reproducibility internally validated. The reliability of this measurement when used outside the trials for defining carotid stenosis has not been validated. Imprecise calculation of carotid stenosis can result in a 50% overestimation of significant carotid disease and potential overuse of carotid surgery. This is a prospective study of the reliability of carotid stenosis measurements performed by practicing physicians of different specialties and different levels of clinical experience.Methods: Two vascular surgeons and two interventional radiologists (one resident and one staff member per specialty), blinded to results, calculated the percent stenosis from 219 consecutive arteriograms performed to evaluate extracranial carotid artery occlusive disease; 72 random films were reread by each individual. The interpretations were grouped as <60% or ≥60% stenosis (ACAS) and as <30%, 30% to 69%, and ≥70% stenosis (NASCET). Interobserver and intraobserver agreement were analyzed with the kappa statistic and Pearson correlation coefficients.Results: Interobserver reliability in categorizing carotid stenosis revealed excellent agreement for both ACAS (κ = 0.825 to 0.903) and NASCET groups (κ = 0.729 to 0.793). Interobserver correlation coefficients ranged from 0.91 to 0.95. Intraobserver agreement was also highly reproducible for both the ACAS (κ = 0.732 to 0.970) and NASCET categories (κ = 0.634 to 0.805). Intraobserver correlation coefficients ranged from 0.89 to 0.95.Conclusion: The NASCET technique for quantification of carotid stenosis can be easily learned by physicians and reliably implemented for appropriate identification of candidates for carotid endarterectomy. (J Vasc Surg 1996;24:449-56.)     

Reappraisal of velocity criteria for carotid bulb/internal carotid artery stenosis utilizing high-resolution B-mode ultrasound validated with computed tomography angiography

OBJECTIVE: Reliability of the most commonly used duplex ultrasound (DUS) velocity thresholds for internal carotid artery (ICA) stenosis has been questioned since these thresholds were developed using less precise methods to grade stenosis severity based on angiography. In this study, maximum percent diameter carotid bulb ICA stenosis (European Carotid Surgery Trial [ECST] method) was objectively measured using high resolution B-mode DUS validated with computed tomography angiography (CTA) and used to determine optimum velocity thresholds for > or =50% and > or =80% bulb internal carotid artery stenosis (ICA). METHODS: B-mode DUS and CTA images of 74 bulb ICA stenoses were compared to validate accuracy of the DUS measurements. In 337 mild, moderate, and severe bulb ICA stenoses (n = 232 patients), the minimal residual lumen and the maximum outer bulb/proximal ICA diameter were determined on longitudinal and transverse images. This in contrast to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) method using normal distal ICA lumen diameter as the denominator. Severe calcified carotid segments and patients with contralateral occlusion were excluded. In each study, the highest peak systolic (PSV) and end-diastolic (EDV) velocities as well as ICA/common carotid artery (CCA) ratio were recorded. Using receiver operating characteristic (ROC) analysis, the optimum threshold for each hemodynamic parameter was determined to predict > or =50% (n = 281) and > or =80% (n = 62) bulb ICA stenosis. RESULTS: Patients mean age was 74 +/- 8 years; 49% females. Clinical risk factors for atherosclerosis included coronary artery disease (40%), diabetes mellitus (32%), hypertension (70%), smoking (34%), and hypercholesterolemia (49%). Thirty-three percent of carotid lesions (n = 110) presented with ischemic cerebrovascular symptoms and 67% (n = 227) were asymptomatic. There was an excellent agreement between B-mode DUS and CTA (r = 0.9, P = .002). The inter/intraobserver agreement (kappa) for B-mode imaging measurements were 0.8 and 0.9, respectively, and for CTA measurements 0.8 and 0.9, respectively. When both PSV of > or =155 cm/s and ICA/CCA ratio of > or =2 were combined for the detection of > or =50% bulb ICA stenosis, a positive predictive value (PPV) of 97% and an accuracy of 82% were obtained. For a > or =80% bulb ICA stenosis, an EDV of > or =140 cm/s, a PSV of > or =370 cm/s and an ICA/CCA ratio of > or =6 had acceptable probability values. CONCLUSION: Compared with established velocity thresholds commonly applied in practice, a substantially higher PSV (155 vs 125 cm/s) was more accurate for detecting > or =50% bulb/ICA stenosis. In combination, a PSV of > or =155 cm/s and an ICA/CCA ratio of > or =2 have excellent predictive value for this stenosis category. For > or =80% bulb ICA stenosis (NASCET 60% stenosis), an EDV of 140 cm/s, a PSV of > or =370 cm/s, and an ICA/CCA ratio of > or =6 are equally reliable and do not indicate any major change from the established criteria. Current DUS > or =50% bulb ICA stenosis criteria appear to overestimate carotid bifurcation disease and may predispose patients with asymptomatic carotid disease to untoward costly diagnostic imaging and intervention.     

Audit of 149 consecutive carotid endarterectomies performed by a single surgeon in a district general hospital over a 12-year period.

Carotid endarterectomy has been established by two large randomised controlled trials (European Carotid Surgery Trial (ECST) and North American Symptomatic Carotid Endarterectomy Trial (NASCET)) as an important surgical procedure for the prevention of ischaemic strokes in patients presenting with transient cerebral ischaemia or non-disabling strokes attributable to severe ipsilateral carotid artery stenosis. The operation carries significant risk of death and stroke and it has been advocated by some that carotid endarterectomy should only be performed in a small number of designated regional centres in order to achieve good surgical results. It is doubtful that the regional centres alone can cope with the increasing numbers of patients requiring carotid endarterectomy and there is therefore a requirement for the procedure to be carried out by vascular surgeons in district general hospitals. It is important that surgical results are audited to ensure that comparable outcomes are achieved. We present an audit of our experience of carotid endarterectomy since 1981. A total of 149 consecutive carotid endarterectomies were performed by a single surgeon with a special interest in carotid surgery. The results are comparable to ECST with a 30-day mortality of 0% and an overall 30-day stroke rate of 5.7% (major strokes) for patients with severe, ie 70-99%, ipsilateral carotid artery stenoses. We have shown that carotid endarterectomy is an operation that can be performed safely and with good results by suitably trained surgeons in district general hospitals.     

Behandlung der Karotisstenose durch Stentimplantation

The incidence of arterioarterial stroke originating from the supra-aortic branches is 187/100,000/year.The 90-day prognosis shows a probability of 15% mortality and 19% severe disability. Based on the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST), the indications for endarterectomy have a high level of evidence. Recommendations for carotid endarterectomy depending on the perioperative risk are defined in the American Heart Association (AHA) and European Stroke Initiative (EUSI) proposals. Several trials have shown that stent supported carotid angioplasty is now an almost equivalent alternative for short-term and intermediate-term follow-up, and an even safer alternative technique in surgically high risk patients. However, the following contraindications must be taken into consideration: thrombosis of the internal carotid artery, long stenoses, aneurysms of the aortic arch with involvement of the supra-aortic branches, carotid occlusion in cases of maintenance of the branchial artery coiling of the internal exit area, as well as severe contrast medium allergy. For the endovascular surgeon this implies the need to learn about and to be involved in using this challenging technique. This therapeutic option allows patient oriented therapy and may further reduce the overall complication rate of carotid stenosis therapy.     

Variability in measurement of internal carotid artery stenosis by arch angiography and duplex ultrasonography--time for a reappraisal?

OBJECTIVES: to determine the inter- and intra-observer variability of ICA stenosis measurement using duplex, ECST and NASCET methods. DESIGN: a retrospective review of arch angiograms and carotid duplex scans in 50 patients. MATERIALS AND METHODS: carotid stenoses were calculated by three independent observers according to NASCET and ECST methods. Variation between observers for NASCET and ECST was determined. For each observer, the variation between NASCET and ECST was determined. The variation between duplex and both NASCET and ECST was determined. RESULTS: inter-observer agreement on the degree of ICA stenosis was clinically and statistically good for NASCET but was poorer for ECST. For each observer, comparison between NASCET and ECST showed 95% limits of agreement of around 50 percentage points. Comparison of duplex with NASCET and ECST showed similar 95% limits of agreement. CONCLUSIONS: arch angiography allows reproducible measurement of carotid stenosis by the NASCET method between different observers. For the ECST method, reproducibility is not so good. Variations in results between NASCET and ECST and between angiography and duplex are significant. In view of the similar results of the NASCET and ECST trials, this suggests that degree of stenosis may only be a surrogate marker for outcome following carotid endarterectomy.     

Prospective evaluation of new duplex criteria to identify 70% internal carotid artery stenosis

Purpose: Large multicenter trials (North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial) have documented the benefits of carotid endarterectomy for treating symptomatic patients with ≥70% stenosis of the internal carotid artery. Although color-flow duplex scanning has become the preferred method for noninvasive assessment of internal carotid artery disease, no criteria have been generally accepted to identify this subset of patients. We previously reported a retrospective series to establish such criteria. This study details our results when these criteria were applied prospectively.Methods: Carotid color-flow duplex scans were compared with arteriograms in 457 patients who underwent both studies. Criteria for ≥70% internal carotid artery stenosis were peak systolic velocity >130 cm/sec and end-diastolic velocity >100 cm/sec. Internal carotid arteries with peak systolic velocity <40 cm/sec in which only a trickle of flow could be detected were classified as preocclusive lesions (95% to 99% stenosis). Arteriographic stenosis was determined by comparing the diameter of the internal carotid artery at the site of maximal stenosis to the diameter of the normal distal internal carotid artery.Results: Internal carotid artery stenosis of ≥70% was detected with a sensitivity of 87%, specificity of 97%, positive predictive value of 89%, negative predictive value of 96%, and overall accuracy of 95%. Eighty-seven percent of 70% to 99% stenoses were correctly identified. False-positive errors (n = 10) were attributed to contralateral internal carotid artery occlusion or high-grade (>90%) stenosis (n = 5) and to interpreter error (n = 1); no explanation was apparent in the other four. Eleven of 12 false-negative examinations occurred in patients with 70% to 80% internal carotid artery stenosis.Conclusions: In our laboratories, prospective application of the above velocity criteria identified internal carotid artery stenosis of ≥70% with a reasonably high degree of accuracy. Errors occurred when stenoses were borderline and in patients with severe contralateral disease. With suitably modified velocity criteria, color-flow duplex scanning remains the most reliable noninvasive method for identifying symptomatic patients who are candidates for carotid endarterectomy. (J V ASC S URG 1996;23:254-62.)     

Aktueller Status von ECST-2

Background

Carotid endarterectomy (CEA) is a common procedure performed in patients who have suffered a stroke or transient ischaemic attack (TIA) to prevent a recurrent event. Clinical trials have provided evidence for the safety and efficacy of CEA in patients with recently symptomatic stenosis. Carotid artery stenting is an alternative to CEA. However, medical treatment has improved in the last 30 years and trials are ongoing to assess the use of modern medical treatment in selected patients with carotid disease as an alternative to revascularization.

Methods

We have reviewed the published results from clinical trials investigating the best treatment for symptomatic and asymptomatic carotid artery stenosis. In this review we discuss carotid endarterectomy, stenting and medical treatment. We have also included an update on the Second European Carotid Surgery Trial (ECST-2) which is an ongoing trial comparing revascularization to optimized medical therapy in patients with low to intermediate risk of recurrent stroke.

Results

The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST) both show that patients with high-risk symptomatic carotid stenosis benefit from CEA over medical treatment alone. However, it has been shown that surgery appeared to be harmful or at least not beneficial in patients included in the trials whose characteristics predicted a low risk of recurrent stroke. The Asymptomatic Carotid Surgery Trial (ACST) also showed a small benefit in treating asymptomatic patients with CEA over medical therapy. Several published trials have compared stenting with endarterectomy and although endarterectomy appears safer in the short term, both treatments have similar long-term outcomes; therefore stenting can be used as an alternative to CEA for selected patients.

Conclusion

CEA and stenting can both be offered to patients with recently symptomatic carotid stenosis to prevent recurrent stroke. We await the results of current trials investigating the role of modern medical therapy in selected patients with low to intermediate risk of recurrent stroke as an alternative to revascularization. The English full-text version of this article is available at SpringerLink (under “Supplemental”).     

Comparison of North American Symptomatic Carotid Endarterectomy Trial and population-based outcomes for carotid endarterectomy

Purpose: The North American Symptomatic Carotid Endarterectomy Trial (NASCET) advocated the use of carotid endarterectomy (CEA) for transient ischemic attacks (TIAs), nondisabling strokes, and ipsilateral high-grade stenosis in highly selected patients. Whether similar results are achieved when CEA is applied to an entire geographically defined population is unknown but important if the NASCET recommendations are to be applied broadly to all community patients. Methods: To determine the survival rate to ipsilateral stroke after CEA for all symptomatic patients in a defined population, we reviewed the medical records of all patients residing in Olmsted County, Minn. (approximately 100,000), who underwent a CEA for TIA or nondisabling stroke between 1970 and 1995. Their outcomes were compared with the NASCET results. Results: In the community of Olmsted County, 297 patients (108 women and 189 men) underwent 322 CEAs during the study period. TIAs or nondisabling stroke was the indication in 254 patients (86%), whereas the remaining 14% had asymptomatic stenosis. After CEA for symptomatic lesions, survival rate free of ipsilateral stroke was 97% at 2 years, 93% at 5 years, and 92% at 10 years. These results are similar to the NASCET survival rates free of ipsilateral stroke at 2 years (91%). However, the 30-day postoperative stroke rate for patients older than 80 years was significantly higher than that for patients younger than 80 years. Conclusions: When the NASCET results are compared with a population-based experience in which all symptomatic patients undergoing CEA were analyzed, the early outcomes were similar. Our population-based data also document the remarkably durable long-term results of CEA in preventing stroke and present another benchmark for carotid stent angioplasty. (J Vasc Surg 1998;27:845-51.)     

Effect of image normalization on carotid plaque classification and the risk of ipsilateral hemispheric ischemic events: results from the asymptomatic carotid stenosis and risk of stroke study

The aim of this study was to determine the effect of image normalization on plaque classification and the risk of ipsilateral ischemic neurologic events in patients with asymptomatic carotid stenosis. The first 1,115 patients recruited to the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study with a follow-up of 6 to 84 months (mean 37.1 months) were included in this study. Duplex ultrasonography was used for grading the degree of internal carotid artery stenosis and for plaque characterization (types 1-5), which was performed before and after image normalization. One hundred sixteen ipsilateral ischemic hemispheric events occurred. Image normalization resulted in 60% of plaques being reclassified. Before image normalization, a high event rate was associated with all types of plaque. After image normalization, 109 (94%) of the events occurred in patients with plaque types 1 to 3. For patients with European Carotid Stenosis Trial (ECST) 70 to 99% diameter stenosis (equivalent to North American Symptomatic Carotid Endarterectomy Trial [NASCET] 50-99%) with plaque types 1 to 3, the cumulative stroke rate was 14% at 7 years (2% per year), and for patients with plaque types 4 and 5, the cumulative stroke rate was 0.9% at 7 years (0.14% per year). The results suggest that asymptomatic patients with plaque types 4 and 5 classified as such after image normalization are at low risk irrespective of the degree of stenosis.     

Computed tomography angiography validates duplex sonographic evaluation of carotid artery stenosis

Controversy regarding the optimal preoperative evaluation for patients with carotid arterial stenosis remains controversial. We hypothesized that carotid artery area reduction measured by computed tomography angiography (CTA) would closely correlate with duplex scanning stenosis. This study was undertaken to evaluate the correlation between duplex, CTA, and conventional arteriography in patients undergoing consideration for carotid endarterectomy. Patients undergoing evaluation for carotid artery stenosis who received at least 2 of the diagnostic tests were included in this study (n = 108); 30 patients underwent all 3 imaging modalities. Linear regression analysis was performed to determine correlation coefficients between the 3 different study modalities. Correlation and P values were as follows: CTA area versus CTA diameter, r = 0.82, P < 0.001; CTA area versus duplex stenosis, r = 0.71, P < 0.001; duplex stenosis versus angio diameter, r = 0.68; P = 0.005; CTA diameter versus angio diameter, r = 0.61, P = 005. CTA was able to identify plaque characteristics more readily than duplex or arteriography. CTA was also able to differentiate critical stenosis from occlusion and to settle discrepancies obtained from duplex scanning. CTA is an acceptable alternative method to validate duplex scanning evaluation of carotid artery stenosis. It can accurately measure lumen stenosis, visualize plaque morphology, and is associated with fewer complications than conventional angiography.     

Symptomatic carotid stenosis: endarterectomy, stenting, or best medical management?

In the past, management of symptomatic carotid stenosis was uncertain. The results of the North American Symptomatic Carotid Endarterectomy Trial (NASCET) in 1991 demonstrated a significant advantage of Carotid Endarterectomy (CEA) compared to medical management with Aspirin (ASA). Since the publishing of the NASCET results, there have been advances in both the medical management of patients with peripheral arterial disease as well as the introduction and improvement of the technique of minimally invasive carotid angioplasty and stenting. With this progress, the question has to be raised about what is the most appropriate treatment option for patients with symptomatic carotid artery stenosis. A review of the prospective clinical trials regarding the medical, surgical and endovascular management will help to elucidate the optimal therapy for symptomatic carotid stenosis.     

颈动脉内膜剥脱与支架置入术患者围手术期脑灌注对比分析

目的:通过全脑CT灌注成像(WBCTP)分析并比较颈动脉内膜剥脱术(CEA)与颈动脉支架成形术(CAS)对颈动脉狭窄患者围手术期脑灌注的影响及差异。方法:参照北美症状性颈动脉内膜切除术(NASCET)标准,选择32例经全脑动脉造影确诊颈动脉狭窄的患者,其中行CEA 11例、行CAS 21例。所有患者术前、术后1周均行WBCTP检查采集脑灌注数据,分析并比较两组相对脑血流量(r CBF)、相对脑血容量(r CBV)、相对平均通过时间(r MTT)的变化及差异。结果:与术前比较,两组患者术后r CBF、r CBV、r MTT均明显改善(均P0.05),两组间以上指标变化程度均无统计学差异(均P0.05)。结论:CEA、CAS两种术式均可改善颈动脉狭窄患者脑灌注,且疗效相似。     

Carotid Endarterectomy for Symptomatic,but “Haemodynamically Insignificant” Carotid Stenosis

ObjectiveCarotid endarterectomy (CEA) guidelines in symptomatic carotid stenosis are based on NASCET and ECST criteria with 70% or greater carotid stenosis as estimated from a catheter angiogram the major indication. This has several problems: (1) lack of reliable correlation between non-invasive imaging and catheter angiography, which has been largely superseded by non-invasive imaging in investigating carotid stenosis; (2) errors inherent in estimating the degree of stenosis from catheter angiography; (3) disregard for the fact that stroke risk also depends on plaque stability, and number of ischaemic events.MethodsA retrospective review of ischaemic events, imaging results, operative findings, surgical complications and stroke-free follow-up in 31 patients presenting over a 23 year period with TIA/stroke (symptoms lasting > 24 h and/or imaging evidence of infarction) who had 70% or less carotid stenosis (on non-invasive imaging), but nonetheless underwent CEA.ResultsNineteen patients had small strokes, 7 had TIAs and 5 had ocular events; 28 patients had features of unstable plaque on imaging; 19 patients experienced multiple events before CEA. All had haemorrhagic, ruptured plaque at CEA. One patient suffered an intra-operative stroke, only 1 patient suffered a further stroke/TIA (mean follow-up 4.2 years).ConclusionTo predict the likelihood of major stroke in symptomatic carotid stenosis and the benefit of CEA, plaque stability and the number of ischaemic events might be as important as an estimate of the degree of stenosis.     

Long-term results of carotid stenting are competitive with surgery

OBJECTIVE: The feasibility of carotid stenting (CS) is no longer questionable, although its indications remain debatable. Until the results of randomized trials are available, personal series and registries should help in the comparison of long-term results of CS with those of endarterectomy. We report here the long-term results of a large series of CS in our department with a long follow-up. This retrospective study reviews a single surgeon's 11-year experience with CS. Our results are compared with those of conventional surgery emanating from our own series and the North American Symptomatic Carotid Endarterectomy Trial (NASCET), European Carotid Surgery Trial (ECST), and Asymptomatic Carotid Atherosclerosis Study (ACAS). MATERIALS AND METHODS: CS has been performed in our department in a single, semi-private institution for 12 years. Patients with high lesions, and postradiotherapy and postendarterectomy stenoses were treated with CS, as were patients at high risk for surgery. The others were operated on with conventional endarterectomy. During the study, we performed 221 CS procedures on 193 patients (150 men and 43 women). The average follow-up was 2.7 years (1 month to 9.3 years). We analyzed the late results in terms of prevention from stroke, the freedom from new neurologic events, and also patency rates of the treated carotid vessels. We also identified predictors for neurologic complication and in-stent restenosis by using univariate analysis. RESULTS: Life-table analyses at 10 years gave a 96% (confidence interval [CI] = 3%) rate for stroke freedom, a 98% (CI = 2%) rate for fatal stroke freedom, and a primary assisted patency rate of 95% (CI = 3%). Predictors for neurologic complication were [corrected] age >70 ( P = .041), and [corrected] potential renal insufficiency ( P = .056 [corrected] In-stent restenosis occurrence extended from 2 months to 4.5 years after the procedure. The restenosis rates at 6 months, 1, 2, and 4.5 years were, respectively, 1.4%, 2.3%, 3.7%, and 5.9% (13/221). No factors were found to be strong predictors of in-stent restenosis [corrected] CONCLUSION: These long-term results show that CS is competitive with conventional surgery. A more accurate selection for CS or surgery might reduce the rate of complications after carotid stenosis repair.     

Severity of asymptomatic carotid stenosis and risk of ipsilateral hemispheric ischaemic events: results from the ACSRS study.

OBJECTIVES: This study determines the risk of ipsilateral ischaemic neurological events in relation to the degree of asymptomatic carotid stenosis and other risk factors. METHODS: Patients (n=1115) with asymptomatic internal carotid artery (ICA) stenosis greater than 50% in relation to the bulb diameter were followed up for a period of 6-84 (mean 37.1) months. Stenosis was graded using duplex, and clinical and biochemical risk factors were recorded. RESULTS: The relationship between ICA stenosis and event rate is linear when stenosis is expressed by the ECST method, but S-shaped if expressed by the NASCET method. In addition to the ECST grade of stenosis (RR 1.6; 95% CI 1.21-2.15), history of contralateral TIAs (RR 3.0; 95% CI 1.90-4.73) and creatinine in excess of 85 micromol/L (RR 2.1; 95% CI 1.23-3.65) were independent risk predictors. The combination of these three risk factors can identify a high-risk group (7.3% annual event rate and 4.3% annual stroke rate) and a low risk group (2.3% annual event rate and 0.7% annual stroke rate). CONCLUSIONS: Linearity between ECST per cent stenosis and risk makes this method for grading stenosis more amenable to risk prediction without any transformation not only in clinical practice but also when multivariable analysis is to be used. Identification of additional risk factors provides a new approach to risk stratification and should help refine the indications for carotid endarterectomy.