Immediate and long-term results of carotid endarterectomy

We review the long-term results of carotid endarterectomy in 200 consecutive patients operated on from 1980 to 1987. The patients were part of an ongoing study using duplex scanning to assess the status of the carotid bifurcation before and after endarterectomy. The average follow-up for the patients was 31 months. The indications for surgery were transient ischemic attacks in 87 (43.5%) and stroke in 36 (18%) patients; 77 patients (38.5%) were asymptomatic. In 176 sides (88%), the degree of stenosis exceeded 50% in terms of diameter reduction. The perioperative stroke rate was 2.3% in patients with transient ischemic attacks, 2.8% in patients with strokes, and 1.3% in asymptomatic patients. There was one perioperative death (0.5%). There were five occlusions of the internal carotid artery, one during the perioperative period and four after discharge; in three patients the occlusion was associated with the development of a stroke. There was a restenosis rate of 19.7% secondary to myointimal hyperplasia; such lesions did not appear to contribute to new ischemic events during or after their development. The mean stroke incidence after the decision was made for carotid endarterectomy was 2.8%/yr in the patients with transient ischemic attacks, 6.2%/yr in the patients with stroke, and 0.65%/yr in the asymptomatic patients. The annual death rate was 6% for the entire group, 5.5%/yr in the patients with transient ischemic attacks, 9.2%/yr in the patients with stroke, and 4.6%/yr in the asymptomatic patients.     

Controversies in neurology: asymptomatic carotid stenosis—intervention or just stick to medical therapy. The argument for carotid endarterectomy

Patients with a significant carotid stenosis are at an increased risk of suffering from a potentially fatal or disabling stroke. The current management strategies available to a patient with an asymptomatic carotid stenosis are either medical therapy alone, or in combination with either carotid endarterectomy, or carotid angioplasty and stenting. Medical therapy alone can reduce the incidence of stroke in general, but whether there is any reduction in stroke attributable to a significant carotid stenosis is less clear. Carotid endarterectomy, on the other hand, has been shown to reduce the incidence of ipsilateral ischaemic stroke in both symptomatic and asymptomatic patients, with the benefits extending into the long-term. Carotid angioplasty and stenting is a newer technique with the benefit of being minimally invasive. The results of trials comparing the technique to endarterectomy have had conflicting results, and the results of large multi-centre trials are awaited. Currently the safest strategy for a patient with a significant asymptomatic carotid stenosis consists of optimal medical therapy with carotid endarterectomy for those less than 75 years of age, who are suitable for surgery.     

Multicenter retrospective review of results and complications of carotid endarterectomy in 1981

A multicenter retrospective audit of carotid endarterectomies performed during 1981 was completed with 46 institutions contributing 3,328 cases. Overall, there was a 2.5% risk of transient neurological dysfunction following surgery and a 6% risk of stroke or death. The intra-institutional combined major morbidity and mortality varied from 21% to 0. Those institutions with greater than 700 beds had a statistically lower incidence of stroke or death than did other institutions. The incidence of stroke or death postoperatively was significantly lower for patients who were operated on for amaurosis fugax or for unspecified reasons. Those patients who were operated on for a progressing stroke had a higher incidence of stroke but this group was at greatest risk for stroke without surgery. The incidence of postoperative stroke or death was related to the type of arterial repair; vein patch grafting was statistically better than both fabric patch grafting and primary closure. When all patients who were not monitored during surgery were compared to all patients who had electroencephalographic (EEG) monitoring, there was found to be a significant statistical difference in favor of the EEG group. Endarterectomy combined with coronary artery bypass or simultaneous bilateral endarterectomies had a statistically significant higher incidence of stroke or death than did unilateral carotid endarterectomy.     

Endarterectomy for carotid stenosis: new approaches in patient selection

Results of randomized trials on carotid endarterectomy make it mandatory that therapeutic decisions for patients with carotid stenosis consider the degree of stenosis, presence of symptoms, skill of surgeon and time since the last ischemic event. Patients with severe (>70% by angiogram) stenosis should receive carotid endarterectomy, provided the operative risk is <6% and symptoms have recurred within 6 months. With moderate stenosis (50--69% by angiogram), and with similar low operative risk and time limit, males with hemispheric, nondisabling stroke and appropriate CT lesion will benefit from carotid endarterectomy. Patients with TIA only, retinal symptoms alone and who are women are not going to benefit in this range of stenosis. Particularly at risk with medical care alone are symptomatic patients with coexistent intracranial stenosis, widespread white-matter lesions, intraluminal thrombi, contralateral occlusion and absence of good collateral circulation. The same high-risk patients, enjoy good long-term results from endarterectomy. Lacunar syndromes at presentation respond to endarterectomy, but with less benefit. Symptomatic patients do as well, regardless of age, provided patients with serious cardiac disorders and with organ failure are avoided. Serious doubt exists about indications for endarterectomy in asymptomatic subjects. Even if the upper limit of 3% perioperative risk is exceeded (and in large institutional databases and other studies, it usually is), the risk of large-artery strokes from the asymptomatic lesion is only slightly above the risk facing these subjects from lacunar and cardioembolic stroke. To prevent 1 large-artery stroke in 5 years in asymptomatic subjects requires that 111 subjects be submitted to endarterectomy.     

Carotid Doppler - costs and need after stroke or TIA

OBJECTIVES: To estimate the need for and the costs of carotid Doppler and carotid endarterectomy after stroke or TIA in non-selected hospitalized patients. MATERIAL AND METHODS: During 25 months hospitalized patients with stroke or TIA, in whom carotid endarterectomy could be relevant, were examined with carotid Doppler. If a significant stenosis was found, they were further evaluated for surgery. Based on our results, the requirement for future carotid endarterectomy and Doppler screening was estimated, and the costs of the procedures calculated. RESULTS: Among 1351 patients 703 were screened with carotid Doppler. Forty-five had severe (70-99%) stenosis of the relevant carotid artery. Only 3 were operated on. The future costs of screening were estimated under different assumptions. CONCLUSION: Carotid endarterectomy is expensive due to the large number of patients screened with carotid Doppler per operated patient. A careful clinical selection of patients for screening is necessary.     

Prognosis of asymptomatic carotid occlusion

Ninety-four asymptomatic patients with internal carotid artery occlusion were followed for a mean of 44 months, 16% suffered strokes and 11.7% reported transient ischemic attacks (TIA). The annual stroke and TIA rates were 4.4% and 3.2%, respectively, the annual mortality was 11.3%. In 27 asymptomatic patients progression of extracranial arterial disease to occlusion was observed: 7.4% of these patients suffered from stroke and 18.5% reported TIA's during that period. Thus the annual stroke rate was lower (1.9%) but the TIA rate higher (4.7%) than post-occlusive rates. These data reflect an increase risk in patients with progressive high-degree carotid stenosis which continues after occlusion. This may favour carotid endarterectomy for selected patients in the pre-occlusive state because medical treatment has not been shown to prevent progression of stenosis to occlusion.     

Carotid angioplasty and stenting: caveat emptor!

Carotid endarterectomy effectively reduces stroke in patients with TIA or minor stroke and a high-grade carotid stenosis. Carotid endarterectomy is also beneficial in male asymptomatic patients younger than 75 years with high-grade stenosis. Carotid stenting has not been as thoroughly evaluated as carotid endarterectomy in randomized trials. The few trials that have been performed up to now show either inferior results or suggest equivalence. Before accepting carotid stenting as a mainstream treatment for carotid stenosis, this therapy should be as critically evaluated as carotid endarterectomy was in the 1980s and 1990s.     

The prognosis of carotid siphon stenosis

We retrospectively reviewed the clinical course and angiograms of 15 patients with carotid siphon stenosis of 50% or greater. Fourteen had less than 50% stenosis at the origin of the ipsilateral internal carotid artery, and one had a greater degree of stenosis but underwent endarterectomy after an initial angiogram. Angiograms were examined for evidence of hemodynamic abnormalities in addition to residual lumen diameter. Seven patients initially had TIAs, 5 had strokes, and 3 were asymptomatic. In an average followup of 51 months (range 4-123 months) subsequent cerebral ischemic events occurred in 6 (40%), but only 1 had a stroke with a persisting neurological deficit that could be directly attributed to the siphon stenosis. Stenoses were hemodynamically significant by angiography in 5 of 7 TIA patients, and only 1 of 5 stroke patients. The incidence of subsequent ischemic events in this study was similar to 2 previous studies of siphon stenosis, however in this study most of the events ipsilateral to the siphon stenosis were TIAs or minor strokes. The association of hemodynamic angiographic abnormalities and initial TIAs but not strokes suggests that the mechanism producing ischemic symptoms may differ in patients with TIA and stroke who have carotid siphon stenosis.     

Clustering of risk factors increases the incidence of echolucent carotid plaque in stroke patients

BACKGROUND: The purpose of this study was to assess the influence of clusters of risk factors on the incidence of echolucent carotid plaque in stroke patients. METHODS: A retrospective analysis of 413 stroke patients who had undergone carotid ultrasonography was performed. High-resolution B-mode ultrasonography was used to evaluate the characteristics of carotid plaque. We investigated the relationships between the incidence of echolucent carotid plaque and clustering of risk factors (hypertension, diabetes mellitus and hyperlipidemia) and stroke subtypes and transient ischemic attack (TIA). RESULTS: Echolucent plaques were present in 10.5% of patients free of risk factors, in 18.8% with a single risk factor (NS), in 27.7% with two risk factors (p <0.01) and in 50.0% with three risk factors (p <0.001), and were significantly more common in patients with multiple risk factors (odds ratio 1.79; 95% CI, 1.05-3.06; p = 0.045). Echolucent plaques were observed in 41.2% of patients with atherothrombotic infarction, in 17.6% with lacunar infarction, in 11.5% with cardioembolic stroke, and in 25.0% with TIA, and were significantly more common in patients with atherothrombotic infarction than in those with lacunar infarction or cardioembolic stroke (p<0.001), or in those with TIA (p <0.05). CONCLUSIONS: The clustering of risk factors increased the incidence of echolucent carotid plaque. Patients with multiple risk factors were at increased risk of echolucent plaque, and these had a significant relationship with atherothrombotic infarction compared with other stroke subtypes and TIA.     

Asymptomatic embolization predicts stroke and TIA risk in patients with carotid artery stenosis.

BACKGROUND AND PURPOSE: Improved methods of identifying patients at high risk of thromboembolism would allow improved targeting of therapy. One such situation is carotid artery stenosis. This is associated with an increased risk of stroke, which can be reduced by carotid endarterectomy. However, the risk-benefit ratio is low in patients with tight asymptomatic stenosis and moderate symptomatic stenosis. Most stroke in patients with carotid stenosis is believed to be embolic. Therefore, the detection of asymptomatic cerebral emboli using Doppler ultrasound may allow identification of a high-risk group. METHODS: Transcranial Doppler ultrasound was used to record for 1 hour the ipsilateral middle cerebral artery in 111 patients with >60% carotid artery stenosis (69 symptomatic, 42 asymptomatic). The Doppler audio signal was recorded onto digital audio tape for later analysis for embolic signals (ES) by an individual blinded to clinical details. In 67 subjects the relationship between ES and angiographically determined plaque ulceration was investigated. All subjects were followed up prospectively, and the relationship between ES and risk of future ipsilateral carotid artery territory ischemic events (TIA and stroke) was determined. RESULTS: ES were detected in 41(36.9%) subjects. In symptomatic patients there was a significant inverse relationship between the number of ES per hour and time elapsed since last symptoms (Spearman's rho=-0.2558, P=0.034). ES were more common in subjects with plaque ulceration, with a relative risk of 4. 94 (95% CI, 1.23 to 19.84; P=0.025) after controlling for both symptomatic status and degree of stenosis. The presence of ES at entry was predictive of TIA and stroke risk during follow up in both symptomatic (P=0.02) and asymptomatic patients (P=0.007). Considering all 111 patients, the presence of asymptomatic embolization was predictive of a further ischemic event, with an adjusted OR of 8.10 (95% CI, 1.58 to 41.57; P=0.01) after controlling for other cardiovascular risk factors, degree of stenosis, symptomatic status, and aspirin or warfarin use. CONCLUSIONS: Asymptomatic embolization in patients with carotid artery stenosis correlates with known markers of increased stroke risk and is an independent predictor of future stroke risk in patients with both symptomatic and asymptomatic carotid stenosis. It may allow identification of a high-risk group of patients who will particularly benefit from carotid endarterectomy. A large multicenter study is now required to confirm these findings.     

Results of carotid endarterectomy with prospective neurologist follow-up

BACKGROUND: Previous studies have shown that neurologic complications following carotid endarterectomy (CE) are underestimated if patients are not examined by neurologists after surgery. OBJECTIVE: To review the morbidity and mortality in a cohort of patients examined before and after CE in a neurology and stroke clinic. METHODS: This was a prospective case series from an academic medical center; 44 patients were referred for CE during the period June 1995 to April 1999. Mean age was 64.3 years; 70.5% were referred for symptomatic stenosis and 29.5% were asymptomatic. Three neurosurgeons and two vascular surgeons operated on the patients. RESULTS: The 30-day mortality rate was 4.5% and the 30-day stroke or death rate was 11.4%. One patient had a TIA due to thrombus formation at the operative site and a second patient had an asymptomatic intimal flap. CONCLUSIONS: With prospective follow-up by neurologists, the CE complication rate in an academic medical center was significantly higher than the rates reported in controlled clinical trials. The generalizability of data from CE clinical trials is limited and local audits are necessary to better establish the risk/benefit ratio for individual hospitals and surgeons.     

Prospective comparison of a cohort with asymptomatic carotid bruit and a population-based cohort without carotid bruit

This study is a prospective analysis of the predictive value of diffuse and localized carotid bruit. Patients with asymptomatic carotid bruits are compared with a population-based age- and sex-matched control group known not to have carotid bruit, in regard to subsequent transient ischemic attack, stroke, and death. Each person was followed until death or for 5 years. Among the 566 patients with asymptomatic carotid bruit, the annual stroke rate given survival was 1.5%/yr or 7.5% at 5 years by actuarial analysis. The annual stroke rate given survival for the 428 patients in the population-based cohort was 0.5%/yr or 2.4% at 5 years. Patients with localized carotid bruit were not significantly different from those with diffuse carotid bruits in regard to subsequent cerebral ischemic events (p = 0.11). These data indicate that patients with asymptomatic diffuse or localized carotid bruit are approximately three times more likely to have ischemic stroke than an age- and sex-matched population sample known not to have carotid bruit.     

Cerebrovascular reactivity in carotid artery occlusion: possible implications for surgical management of selected groups of patients

OBJECTIVES: The aim of this study was to use transcranial Doppler ultrasonography to investigate cerebrovascular reactivity to hypercapnia in the middle cerebral arteries of patients with carotid occlusion with different outcomes. PATIENTS AND METHODS: Cerebrovascular reactivity to hypercapnia was calculated with the breath-holding index (BHI). Patients with unilateral carotid occlusion were divided as follows: asymptomatic (20 patients), transient ischemic attack (TIA) (20 patients), minor (20 patients) and major stroke (14 patients). Values of BHI homolateral to the carotid occlusion were compared with those of 25 healthy subjects and 34 stroke patients without significant carotid stenosis. RESULTS: BHI values were comparable in healthy controls, non stenotic stroke patients and asymptomatic occluded patients. BHI values of patients with symptomatic occlusion were significantly lower than those of the above-mentioned groups (P<0.0001). Moreover, the reduction of BHI was significantly associated with the extent of the neurological impairment. In fact, BHI values were significantly higher in TIA than in minor and major stroke (P<0.0001) and in minor than in major stroke patients (P<0.02). Finally, we found that a BHI value homolateral to carotid occlusion of 0.69 can be considered the cut-point for distinguishing between symptomatic and asymptomatic patients. CONCLUSION: Prospective studies are needed to demonstrate if the presence of this threshold value may help in selecting a subset of patients with asymptomatic carotid occlusion or with transient or mild neurological deficit with the highest probability of benefiting from surgical therapy.     

Preoperative antithrombotic treatment in acutely symptomatic carotid artery stenosis

ObjectivesEarly recurrence of cerebral ischemia in acutely symptomatic carotid artery stenosis can precede revascularization. The optimal antithrombotic regimen for this high-risk population is not well established. Although antiplatelet agents are commonly used, there is limited evidence for the use of anticoagulants. We sought to understand the safety and efficacy of short-term preoperative anticoagulants in secondary prevention of recurrent cerebral ischemic events from acutely symptomatic carotid stenosis in patients awaiting carotid endarterectomy (CEA).Materials and MethodsA retrospective query of a prospective single institution registry of carotid revascularization was performed. Patients who presented with acute ischemic stroke or transient ischemic attack (TIA) attributable to an ipsilateral internal carotid artery stenosis (ICA) were included. Antiplatelet (AP) only and anticoagulation (AC) treatment arms were compared. The primary outcome was a composite of preoperative recurrent ischemic stroke or TIA. The primary safety outcome was symptomatic intracranial hemorrhage.ResultsOut of 443 CEA patients, 342 were in the AC group and 101 in the AP group. Baseline characteristics between groups (AC vs AP) were similar apart from age (71±10.5 vs 73±9.5, p=0.04), premorbid modified Rankin scale (mRS) score (1.0±1.2 vs 1.4±1.3, p=0.03) and stroke as presenting symptom (65.8 vs 53.5%, p=0.02). Patients in the AC group had a lower incidence of recurrent stroke/TIA (3.8 vs 10.9%, p=0.006). One patient had symptomatic intracranial hemorrhage in the AC group, and none in the AP group. In multivariate analysis controlling for age, premorbid mRS, stroke severity, degree of stenosis, presence of intraluminal thrombus (ILT) and time to surgery, AC was protective (OR 0.30, p=0.007). This effect persisted in the cohort exclusively without ILT (OR 0.23, p=0.002).ConclusionsShort term preoperative anticoagulation in patients with acutely symptomatic carotid stenosis appears safe and effective compared to antiplatelet agents alone in the prevention of recurrent cerebral ischemic events while awaiting CEA.     

Combining carotid endarterectomy with off-pump coronary artery bypass graft surgery is safe and effective

Background:

We, as neurologists, are frequently consulted to give neurological clearance for surgery in patients who are undergoing coronary artery bypass graft (CABG) surgery and have suffered from stroke or transient ischemic attack (TIA) in past. Similarly clearance is also sought in another group of patients who, though have not suffered from stroke or TIA, but found to have significant carotid stenosis on routine screening prior to surgery. Cardiac surgeons and anesthetists want to know the risk of perioperative stroke in such patients and should carotid endarterectomy (CEA) be done along with CABG. In absence of any clear-cut guideline, neurologists often fail to give any specific recommendation.

Aim:

To find out safety and efficacy of synchronous CEA in patients undergoing CABG.

Design:

Retrospective study.

Materials and Methods:

Out of 3,700 patients who underwent CABG, 150 were found to have severe carotid stenosis of >70%. Out of this, 46 patients with >80% stenosis (three symptomatic and 43 asymptomatic) and one patient with >70% symptomatic carotid stenosis (TIA within last 2 weeks) were taken for simultaneous CEA along with CABG. These three symptomatic carotid patients had suffered from stroke within last 6 months.

Results:

One patient with asymptomatic near total occlusion of carotid artery suffered from hyperperfusion syndrome. None suffered from ischemic stroke, myocardial infarction (MI), or death during perioperative period.

Conclusion:

Combining CEA along with CABG is a safe and effective procedure.     

Performance of the ABCD and ABCD2 scores in TIA patients with carotid stenosis and atrial fibrillation

BACKGROUND: It has been suggested that scores for risk stratification of TIA patients might not identify patients with carotid stenosis or atrial fibrillation (AF) and that this might undermine the usefulness of such scores. METHODS: In patients with TIA in the Oxford Vascular Study, we studied the associations between ABCD and ABCD2 scores, the presence of > or =50% ipsilateral carotid stenosis or AF, and the risk of stroke at 7 days. RESULTS: Among 285 TIA patients (from 559 referrals of possible TIA), 69 (24.2%) had either > or =50% carotid stenosis (n = 29) or AF (n = 42), or both (n = 2). Although the ABCD and ABCD2 scores were highly predictive of stroke at 7 days (p < 0.0001), there was no clear relationship between either score and the prevalence of > or =50% carotid stenosis or AF. However, the scores did predict the 7-day stroke risk in patients with these pathologies: ABCD score (trend-p = 0.05); ABCD2 (trend-p = 0.03). Five of the 6 patients with AF or symptomatic stenosis who had a stroke within 7 days of their TIA had an ABCD score of > or =5 and all 6 had an ABCD2 score of > or =4. CONCLUSIONS: The ABCD and ABCD2 risk scores appear to identify patients with > or =50% carotid stenosis or AF who are at high risk of stroke. However, these findings should be interpreted with caution due to the small number of outcomes among these subgroups, and further validations are necessary.     

Declining morbidity and mortality of carotid endarterectomy. The Wake Forest University Medical Center experience

The 30-day mortality as well as morbidity for stroke and myocardial infarction were determined by review of the charts for every carotid endarterectomy (N = 389 operations on 356 patients) performed at Wake Forest University Medical Center from 1979 through 1983 to ascertain whether the 16% morbidity and 6% mortality documented in our previous report of 1978 had changed over time. For endarterectomies performed on asymptomatic patients (n = 155), major morbidity included 2 myocardial infarctions and 1 stroke (1.9%). There were 3 fatalities--2 myocardial infarctions and 1 stroke (1.9%). For the symptomatic group (n = 234), major morbidity was 2.1%, mortality 2.6%. The combined morbidity for asymptomatic and symptomatic carotid stenosis was 2%, mortality 2.3%. Perioperative stroke rate (morbidity plus mortality) was 2.6%, 9 ipsilateral to the carotid endarterectomy, suggesting distal embolism as its probable cause. We contend that quality control measures implemented to correct the unacceptable rates reported in 1978 have contributed to dramatic and sustained reductions in complication rates.     

Low mini-mental status predicts mortality in asymptomatic carotid arterial stenosis. Asymptomatic Carotid Atherosclerosis Study investigators

OBJECTIVE: To determine whether carotid endarterectomy is superior to best medical therapy in preserving cognition, and whether low Mini-Mental State Examination (MMSE) scores predict TIA, stroke, myocardial infarction, or death. METHODS: Subjects participating in the Asymptomatic Carotid Atherosclerosis Study were administered the MMSE at periodic intervals. Group means were calculated at randomization, 1 and 3 months later, and every 6 months thereafter. The group means were compared by treatment and over time. A proportional hazard regression model incorporating postrandomization MMSE score as a predictor variable was used to estimate risk of death, stroke, or other outcome events. RESULTS: There was no intergroup difference in mean MMSE score during 5 years of observation. For individual patients, the relationship between a low postrandomization score on the MMSE and increased risk of death was significant (p 相似文献   

Clinical significance of the ophthalmic artery in carotid artery disease

A total of 141 subjects with tight stenosis (≥75%) or occlusion of internal carotid artery were followed up at intervals 3–6 months regularly for 40 ± 16 months. The direction of ophthalmic artery flow was used as a parameter of risk indicator on cerebral ischemic events. Eleven patients with bilateral carotid tight stenosis/occlusion were excluded in the analysis. Thus, the 130 carotid arteries were divided into three groups: (1) carotid artery with ipsilateral hemispheric TIA or stroke (85 patients), (2) carotid arteries with contralateral hemispheric TIA/stroke or VBI (15 patients), and (3) carotid arteries of asymptomatic patients (30 patients). The symptomatic carotid artery group (group 1) had significantly more often reversed ophthalmic flow than the other two groups (group 2 and 3, p < 0.001). During follow-up prospectively for four years, 41 patients had cerebral ischemic events, three had cardiac ischemic events and six died of malignancy. Patients with reversed OA flow had more often subsequent cerebral ischemic events than those with forward flow (27 vs 14, p = 0.010). However, the difference remained significant only in the asymptomatic patients (group 3, 4 vs 0, P < 0.001), not for groups 1 and 2, after further analysis. Our work supported that the clinical role of ophthalmic artery collateral varied between asymptomatic and symptomatic patients.     

Restenosis after carotid artery stenting and endarterectomy: a secondary analysis of CREST, a randomised controlled trial

BACKGROUND: In the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST), the composite primary endpoint of stroke, myocardial infarction, or death during the periprocedural period or ipsilateral stroke thereafter did not differ between carotid artery stenting and carotid endarterectomy for symptomatic or asymptomatic carotid stenosis. A secondary aim of this randomised trial was to compare the composite endpoint of restenosis or occlusion. METHODS: Patients with stenosis of the carotid artery who were asymptomatic or had had a transient ischaemic attack, amaurosis fugax, or a minor stroke were eligible for CREST and were enrolled at 117 clinical centres in the USA and Canada between Dec 21, 2000, and July 18, 2008. In this secondary analysis, the main endpoint was a composite of restenosis or occlusion at 2 years. Restenosis and occlusion were assessed by duplex ultrasonography at 1, 6, 12, 24, and 48 months and were defined as a reduction in diameter of the target artery of at least 70%, diagnosed by a peak systolic velocity of at least 3·0 m/s. Studies were done in CREST-certified laboratories and interpreted at the Ultrasound Core Laboratory (University of Washington). The frequency of restenosis was calculated by Kaplan-Meier survival estimates and was compared during a 2-year follow-up period. We used proportional hazards models to assess the association between baseline characteristics and risk of restenosis. Analyses were per protocol. CREST is registered with ClinicalTrials.gov, number NCT00004732. FINDINGS: 2191 patients received their assigned treatment within 30 days of randomisation and had eligible ultrasonography (1086 who had carotid artery stenting, 1105 who had carotid endarterectomy). In 2 years, 58 patients who underwent carotid artery stenting (Kaplan-Meier rate 6·0%) and 62 who had carotid endarterectomy (6·3%) had restenosis or occlusion (hazard ratio [HR] 0·90, 95% CI 0·63-1·29; p=0·58). Female sex (1·79, 1·25-2·56), diabetes (2·31, 1·61-3·31), and dyslipidaemia (2·07, 1·01-4·26) were independent predictors of restenosis or occlusion after the two procedures. Smoking predicted an increased rate of restenosis after carotid endarterectomy (2·26, 1·34-3·77) but not after carotid artery stenting (0·77, 0·41-1·42). INTERPRETATION: Restenosis and occlusion were infrequent and rates were similar up to 2 years after carotid endarterectomy and carotid artery stenting. Subsets of patients could benefit from early and frequent monitoring after revascularisation. FUNDING: National Institute of Neurological Disorders and Stroke and Abbott Vascular Solutions.