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Therapeutics

Carotid endarterectomy reduced strokes in patients with recent, nondisabling cerebral ischemic events and severe carotid stenosis

ACP J Club. 1991 Sept-Oct;115:33. doi:10.7326/ACPJC-1991-115-2-033

Related Content in this Issue
• Companion Abstract and Commentary: Carotid endarterectomy reduced death and strokes in patients with ipsilateral high-grade stenosis and recent hemispheric transient ischemic attacks or nondisabling strokes

Related Content in the Archives
Elderly patients had an increased 5-year risk for death, coronary events, and stroke after retinal infarction
Endarterectomy was not effective for moderate symptomatic carotid stenosis


Source Citation

European Carotid Surgery Trialists' Collaborative Group. MRC European Carotid Surgery Trial: interim results for symptomatic patients with severe (70-99%) or with mild (0-29%) carotid stenosis. Lancet. 1991 May 25;337:1235-43. [PubMed ID: 1674060]


Abstract

Objective

To assess the effect of carotid endarterectomy on the duration of nondisabled survival in patients with recent, nondisabling, cerebrovascular ischemic events and ipsilateral carotid stenosis.

Design

Multicenter, randomized, controlled trial with 3-year mean follow-up. Interim results for 2 of 3 entry strata are in this report: 0% to 29% carotid stenosis and 70% to 99% stenosis.

Setting

80 centers in 14 European countries.

Patients

Patients with a carotid-territory, nondisabling ischemic stroke, transient ischemic attack, or retinal infarction within 6 months were included if, after a carotid angiogram, the local neurologist and surgeon were "substantially uncertain" about whether to recommend endarterectomy for the relevant ipsilateral artery. 455 patients with severe stenosis (70% to 99%) and 219 with mild stenosis (0% to 29%) were randomized to surgery; 323 with severe stenosis and 155 with mild stenosis were randomized to no immediate surgery (60:40 randomization). 97% were successfully followed.

Intervention

The surgery group received carotid endarterectomy (median delay, 12 days after randomization). All patients received other appropriate medical care, including aspirin, from their physicians.

Main outcome measures

30-day risk for surgery-associated death or stroke, and 3-year risk for fatal, disabling, or nondisabling stroke of > 7 days duration reviewed by a central, blinded audit committee.

Main results

{96%}* of the severe-stenosis surgery group and {94%}* of the mild stenosis group had surgery; {5%}* of the medical group had surgery. Including a perioperative stroke rate of 8%, the 3-year total risk for surgical death, surgical stroke, and all other strokes was 12% for surgery and 22% for the control group (absolute difference 10% {95% CI 3% to 16%}* P < 0.001). Most strokes were ipsilateral. For disabling or fatal stroke (including surgical death), the rates were 6% for surgery compared with 11% for control (absolute difference 5% {CI 1% to 9%})*.

For patients with mild stenosis the risk for fatal, disabling, or nondisabling strokes was low (9% for surgery vs 5% for control {difference -4%, CI -8% to 4%})*.

Conclusions

Carotid endarterectomy was beneficial for patients with recent, nondisabling cerebral ischemic events and ipsilateral severe (70% to 99%) carotid stenosis. Endarterectomy was not beneficial for patients with mild stenosis (0% to 29%).

Sources of funding: UK MRC; Netherlands Heart Foundation; French INSERM.

Address for article reprint: Dr. C.P. Warlow, Department of Clinical Neurosciences, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, Scotland, UK.

*Numbers calculated from data in article.


Commentary

Carotid endarterectomy reduced death and strokes in patients with ipsilateral high-grade stenosis and recent hemispheric transient ischemic attacks or nondisabling strokes

The ECST and the NASCET are landmark studies. Many clinicians believed that persons with cerebral ischemic symptoms associated with high-grade carotid stenosis benefited from carotid endarterectomy. However, considerable doubt arose about a net benefit to society, given the high risk of surgery reported from some communities and the reported high frequency of inappropriate indications for carotid endarterectomy. These studies do not completely allay the doubt. In both studies the surgeons were carefully chosen and demonstrated lower perioperative morbidity and mortality than shown in community surveys.

The major surprise in these studies is the high risk for stroke in the patients who did not have surgery; 22% in 3 years in ECST and 28% in 2 years in NASCET. The apparently higher risk in NASCET may be at least partly an artifact of their method of measuring stenosis: luminal diameter at greatest stenosis divided by diameter of normal artery beyond the bulb. Previous estimates from population-based studies of 5% per year (1) and of 6% per year among patients who had angiograms but not surgery (2) are misleading. The population-based studies did not separate out patients with high-grade stenosis by angiography, and the patients who had angiograms in the latter study included those with mild stenosis. These are presumed reasons for the underestimates. It would indicate, however, that the prevalence of high-grade stenosis in symptomatic patients in a community would probably be less than 15%.

These 2 trials provide unequivocal evidence of the benefit of carotid endarterectomy by qualified surgeons in patients with severe carotid stenosis. It is less certain where the cut point may be. In NASCET, the patients with 70% to 79% stenosis appear to benefit less than those with 90% to 99% stenosis, and there may not be a net benefit in those with 70% to 79% stenosis. Neither trial has stopped the entry of patients with 30% to 69% stenosis even though there are about 1100 such patients in ECST. This raises questions about the potential benefit in this group.

These 2 trials differ from each other in some ways. ECST used an expedient selection procedure based on the doctors' "substantial uncertainty." This probably provided a wider variety of risk in the patients randomized. In fact, the perioperative mortality and stroke morbidity were higher in ECST than in NASCET. There was also less benefit in ECST. ECST had a less precise design and a simpler format but still required 10 years to produce useful information. NASCET, on the other hand, produced a somewhat greater difference in the treatment groups in 3 years with less opportunity for slippage because the surgical patients had surgery sooner after their qualifying events and after randomization than was the case in ECST.

One of the most important benefits of the positive result of these 2 trials is the demonstration that it is possible to assess carefully the benefits and risks of a surgical procedure and show that it is favorable. Surgeons have often resisted such assessments in favor of judgments about individual patients.

It is important to emphasize that these results do not apply to asymptomatic patients or to patients who have had symptoms for longer than 4 to 6 months. They also do not apply to the patients of all surgeons. A surgeon must demonstrate low surgical mortality and morbidity and careful selection of patients to make the case that the results of these trials apply to his or her patients.

Jack P. Whisnant, MD
Mayo ClinicRochester, Minnesota, USA


References

1. Whisnant JP, Wiebers DO. In: Sundt TM Jr, ed. Occlusive Cerebrovascular Disease: Diagnosis and Surgical Management. Philadelphia: WB Saunders; 1987:60-5.

2. Fields WS, Lemak NA. Joint study of extracranial arterial occlusion. IX. Transient ischemic attacks in the carotid territory. JAMA. 1976;235:2608-10.