Long-term prognosis and the effect of carotid endarterectomy in patients with recurrent ipsilateral ischemic events. North American Symptomatic Carotid Endarterectomy Trial Group

Carotid endarterectomy for symptomatic carotid stenosis

BACKGROUND

Stroke is the third leading cause of death and the most common cause of long-term disability. Severe narrowing (stenosis) of the carotid artery is an important cause of stroke. Surgical treatment (carotid endarterectomy) may reduce the risk of stroke, but carries a risk of operative complications. This is an update of a Cochrane Review, originally published in 1999, and most recently updated in 2017.

OBJECTIVES

To determine the balance of benefit versus risk of endarterectomy plus best medical management compared with best medical management alone, in people with a recent symptomatic carotid stenosis (i.e. transient ischaemic attack (TIA) or non-disabling stroke).

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE Ovid, Embase Ovid, Web of Science Core Collection, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform (ICTRP) portal to October 2019. We also reviewed the reference lists of all relevant studies and abstract books from research proceedings.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing carotid artery surgery plus best medical treatment with best medical treatment alone.  DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies, assessed risk of bias, and extracted the data. We assessed the results and the quality of the evidence of the primary and secondary outcomes by the GRADE method, which classifies the quality of evidence as high, moderate, low, or very low.

MAIN RESULTS

We included three trials involving 6343 participants. The trials differed in the methods of measuring carotid stenosis and in the definition of stroke. Using the primary electronic data files, we pooled and analysed individual patient data on 6092 participants (35,000 patient-years of follow-up), after reassessing the carotid angiograms and outcomes from all three trials, and redefining outcome events where necessary, to achieve comparability. Surgery increased the five-year risk of any stroke or operative death in participants with less than 30% stenosis (risk ratio (RR) 1.25, 95% confidence interval (CI) 0.99 to 1.56; 2 studies, 1746 participants; high-quality evidence). Surgery decreased the five-year risk of any stroke or operative death in participants with 30% to 49% stenosis (RR 0.97, 95% CI 0.79 to 1.19; 2 studies, 1429 participants; high-quality evidence), was of benefit in participants with 50% to 69% stenosis (RR 0.77, 95% CI 0.63 to 0.94; 3 studies, 1549 participants; moderate-quality evidence), and was highly beneficial in participants with 70% to 99% stenosis without near-occlusion (RR 0.53, 95% CI 0.42 to 0.67; 3 studies, 1095 participants; moderate-quality evidence). However, surgery decreased the five-year risk of any stroke or operative death in participants with near-occlusions (RR 0.95, 95% CI 0.59 to 1.53; 2 studies, 271 participants; moderate-quality evidence).

AUTHORS' CONCLUSIONS

Carotid endarterectomy reduced the risk of recurrent stroke for people with significant stenosis. Endarterectomy might be of some benefit for participants with 50% to 69% symptomatic stenosis (moderate-quality evidence) and highly beneficial for those with 70% to 99% stenosis (moderate-quality evidence).

Carotid endarterectomy for symptomatic carotid stenosis

BACKGROUND

Stroke is the third leading cause of death and the most common cause of long-term disability. Severe narrowing (stenosis) of the carotid artery is an important cause of stroke. Surgical treatment (carotid endarterectomy) may reduce the risk of stroke, but carries a risk of operative complications. This is an update of the Cochrane Review, originally published in 1999, and most recently updated in 2011.

OBJECTIVES

To determine the balance of benefit versus risk of endarterectomy plus best medical management compared with best medical management alone, in people with a recent symptomatic carotid stenosis (i.e. transient ischaemic attack (TIA) or non-disabling stroke).

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched in July 2016), CENTRAL (2016, Issue 7), MEDLINE (1966 to July 2016), Embase (1990 to July 2016), Web of Science Core Collection, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP) portal, and handsearched relevant journals and reference lists.

SELECTION CRITERIA

We included randomised controlled trials.   DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies, assessed risk of bias, and extracted the data.

MAIN RESULTS

We included three trials involving 6343 participants. As the trials differed in the methods of measurement of carotid stenosis and in the definition of stroke, we did a pooled analysis of individual patient data on 6092 participants (35,000 patient years of follow-up), after reassessing the carotid angiograms and outcomes from all three trials using the primary electronic data files, and redefined outcome events where necessary, to achieve comparability.On re-analysis, there were no significant differences between the trials in the risks of any of the main outcomes in either of the treatment groups, or in the effects of surgery. Surgery increased the five-year risk of ipsilateral ischaemic stroke in participants with less than 30% stenosis (N = 1746, risk ratio (RR) 1.27, 95% confidence interval (CI) 0.80 to 2.01), had no significant effect in participants with 30% to 49% stenosis (N = 1429, RR 0.93, 95%CI 0.62 to 1.38), was of benefit in participants with 50% to 69% stenosis (N = 1549, RR 0.84, 95%CI 0.60 to 1.18), and was highly beneficial in participants with 70% to 99% stenosis without near-occlusion (N = 1095, RR 0.47, 95%CI 0.25 to 0.88). However, there was no evidence of benefit (N = 271, RR 1.03, 95%CI 0.57 to 1.84) in participants with near-occlusions. Ipsilateral ischaemic stroke describes insufficient blood flow to the cerebral hemisphere, secondary to same side severe stenosis of the internal carotid artery.

AUTHORS' CONCLUSIONS

Endarterectomy was of some benefit for participants with 50% to 69% symptomatic stenosis (moderate-quality evidence), and highly beneficial for those with 70% to 99% stenosis without near-occlusion (moderate-quality evidence). We found no benefit in people with carotid near-occlusion (high-quality evidence).

Risk modeling to identify patients with symptomatic carotid stenosis most at risk of stroke

We have reliable data on the degree of stenosis above which endarterectomy for symptomatic carotid stenosis is beneficial, but benefit is also influenced by other factors, particularly age, sex, the timing of surgery, plaque surface morphology and the nature of the presenting symptomatic event(s). This review will consider the selection of patients for carotid surgery based on the factors that influence the likely risk of stroke on medical treatment. In order to take into account all of the relevant factors, a risk prediction model is considered.

Carotid endarterectomy for symptomatic carotid stenosis

BACKGROUND

Severe narrowing (stenosis) of the carotid artery is an important cause of stroke. Surgical treatment (carotid endarterectomy) may reduce the risk of stroke, but carries a risk of operative complications.

OBJECTIVES

To determine the balance of benefit versus risk of endarterectomy plus best medical management compared with best medical management alone in patients with a recent symptomatic carotid stenosis (i.e. transient ischaemic attack (TIA) or non-disabling stroke).

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (July 2010), MEDLINE (1966 to March 2010), EMBASE (1990 to March 2010) and three other databases, and handsearched relevant journals and reference lists.

SELECTION CRITERIA

Randomised controlled trials.  

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and extracted the data.

MAIN RESULTS

We included three trials. As the trials differed in the methods of measurement of carotid stenosis and in the definition of stroke, we did a pooled analysis of individual patient data on 6092 patients (35,000 patient years of follow-up) after reassessment of the carotid angiograms and outcomes from all three trials using the primary electronic data files and redefined outcome events where necessary to achieve comparability.On re-analysis, there were no statistically significant differences between the trials in the risks of any of the main outcomes in either of the treatment groups or in the effects of surgery. Surgery increased the five-year risk of ipsilateral ischaemic stroke in patients with less than 30% stenosis (N = 1746, absolute risk reduction (ARR) -2.2%, P = 0.05), had no significant effect in patients with 30% to 49% stenosis (N = 1429, ARR 3.2%, P = 0.6), was of marginal benefit in patients with 50% to 69% stenosis (N = 1549, ARR 4.6%, P = 0.04), and was highly beneficial in patients with 70% to 99% stenosis without near-occlusion (N = 1095, ARR 16.0%, P < 0.001). However, there was no evidence of benefit (N = 262, ARR -1.7%, P = 0.9) in patients with near-occlusions.Benefit from surgery was greatest in men, patients aged 75 years or over, and patients randomised within two weeks after their last ischaemic event and fell rapidly with increasing delay.

AUTHORS' CONCLUSIONS

Endarterectomy is of some benefit for 50% to 69% symptomatic stenosis and highly beneficial for 70% to 99% stenosis without near-occlusion. Benefit in patients with carotid near-occlusion is marginal in the short-term and uncertain in the long-term. These results are generalisable only to surgically-fit patients operated on by surgeons with low complication rates (less than 7% risk of stroke and death). Benefit from endarterectomy depends not only on the degree of carotid stenosis, but also on several other factors, including the delay to surgery after the presenting event.

Patient risk perceptions for carotid endarterectomy: which patients are strongly averse to surgery?

BACKGROUND AND PURPOSE

Patient risk perception for surgery may be central to their willingness to undergo surgery. This study examined potential factors associated with patient aversion of surgery.

METHODS

This is a secondary data analysis of a prospective cohort study that examined patients referred for evaluation of carotid artery stenosis at five Veterans Affairs Medical Centers. The study collected demographic, clinical, and psychosocial information related to surgery. This analysis focused on patient response to a question assessing their aversion to surgery.

RESULTS

Among the 1065 individuals, at the time of evaluation for carotid endarterectomy (CEA), 66% of patients had no symptoms, 16% had a transient ischemic attack, and 18% had stroke. Twelve percent of patients referred for CEA evaluation were averse to surgery. In adjusted analyses, increased age, black race, no previous surgery, lower level of chance locus of control, less trust of physicians, and less social support were significantly related to greater likelihood of surgery aversion among individuals referred for CEA evaluation. Patient degree of medical comorbidity and a validated measure of preoperative risk score were not associated with increased aversion to surgery.

CONCLUSIONS

In previous work, aversion to CEA was associated with lack of receipt of CEA even after accounting for patient clinical appropriateness for surgery. We identified important patient characteristics associated with aversion to CEA. Interventions designed to assist patient decision making should focus on these more complex factors related to CEA aversion rather than the simple explanation of clinical usefulness.

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.

Carotid endarterectomy: can we select surgical candidates at high risk for stroke and low risk for perioperative complications?

DESPITE EVIDENCE OF the efficacy of carotid endarterectomy from the large randomized multicenter trials completed in the 1990s, the physician who treats patients with carotid artery stenosis still is faced with a difficult management decision. More recently, subgroup analyses have been conducted of asymptomatic and symptomatic patients enrolled in these trials to identify clinical and radiological factors that increase the rates of morbidity and mortality associated with surgery, as well as those that increase the risk of stroke without surgery. Knowledge of these factors is important to recommend the best course of action for the individual patient. In this article, we summarize the conclusions of some of the subgroup analyses from the major carotid endarterectomy trials.

Carotid endarterectomy for symptomatic carotid stenosis

BACKGROUND

Severe narrowing (or stenosis) of the carotid artery is an important cause of stroke. Surgical removal of the atheromatous material from the inside of the carotid artery (endarterectomy) may reduce the risk of stroke, but carries a risk of operative complications.

OBJECTIVES

This review seeks to summarize the evidence from randomized trials on the balance of risks and benefits of carotid endarterectomy in adults with symptomatic carotid stenosis.

SEARCH STRATEGY

We searched the Cochrane Stroke Group's Specialized Register of trials (date last searched: March 1999), supplemented by electronic searches of several databases.

SELECTION CRITERIA

Randomized controlled trials comparing 'best medical treatment plus carotid endarterectomy' with 'best medical therapy' in patients with carotid stenosis and a recent transient ischaemic attack or nondisabling ischaemic stroke in the territory of that artery.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected the studies and extracted the data. An intention to treat analysis was performed.

MAIN RESULTS

Data on death or disabling stroke were available from two trials, which included 5950 patients: the North American Symptomatic Carotid Endarterectomy Trial (NASCET), and the European Carotid Surgery Trial (ECST). The two trials used different methods to measure stenosis, but a simple formula can be used to convert between the two methods. For patients with severe stenosis (ECST > 80% = NASCET > 70%), surgery reduced the relative risk of disabling stroke or death by 48% (95% confidence interval [CI] 27 - 73%). The number of patients needed to be operated on (number needed to treat [NNT]) to prevent one disabling stroke or death over 2 to 6 years follow-up was 15 (95% CI 10 - 31). For patients with less severe stenosis (ECST 70 - 79% = NASCET 50 - 69%), surgery reduced the relative risk of disabling stroke or death by 27% (95% CI 15 - 44%). The number of patients needed to be operated on to prevent one disabling stroke or death was 21 (95% CI 11 - 125). Patients with lesser degrees of stenosis were harmed by surgery. Surgery increased the risk of disabling stroke or death by 20% (95% CI 0 - 44%). The number of patients needed to be operated on to cause one disabling stroke or death was 45 (95% CI 22 - infinity).

REVIEWER'S CONCLUSIONS

Carotid endarterectomy reduced the risk of disabling stroke or death for patients with stenosis exceeding ECST-measured 70% or NASCET-measured 50%. This result is generalizable only to surgically-fit patients operated on by surgeons with low complication rates (less than 6%).

Refining the indications for carotid endarterectomy in patients with symptomatic carotid stenosis: A systematic review

OBJECTIVE

The purpose of this study was to summarize the existing literature on the efficacy of carotid endarterectomy in patients with ipsilateral symptomatic carotid stenosis.

METHODS

Database searching, relevance assessment, methodologic quality assessments, and data extraction were all performed in duplicate with prespecified criteria.

RESULTS

Twenty-three publications were identified from the North American Symptomatic Carotid Endarterectomy Trial, the European Carotid Surgery Trial, and the Veterans Affairs Cooperative Studies Program. Stenosis was reported as measured in the North American Symptomatic Carotid Endarterectomy Trial. In patients with >70% stenosis, carotid endarterectomy was associated with a pooled relative risk reduction of 48% (95% confidence interval [CI], 27% to 73%) and an absolute risk reduction of 6.7% (95% CI, 3.2% to 10%) for the outcome of death or major disability from stroke. This translates into a number needed to treat of 15 (95% CI, 10 to 31). For patients with 50% to 69% stenosis, the benefit of surgery was less and the confidence intervals were wider. A relative risk reduction of 27% (95% CI, 5% to 44%), an absolute risk reduction of 4.7% (95% CI, 0.8% to 8.7%), and a number needed to treat of 21 (95% CI, 11 to 125) were observed in this group. The patients with the lowest degrees of stenosis (<50%) were harmed by the intervention (number needed to harm, 45). Increasing degree of stenosis, increasing age, male sex, the presence of other medical risk factors, and the presence of hemispheric rather than retinal antecedent events were factors that increased the benefits from surgery.

CONCLUSION

Carotid endarterectomy reduced death or major disability from stroke in patients with >50% symptomatic stenosis. To maximize the benefits of surgery, careful preoperative risk assessment and the maintenance of low rates of major perioperative complications are mandatory.