The NASCET: Carotid endarterectomy for symptomatic stenosis [Classics Series]

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1. Carotid endarterectomy, in addition to medical therapy, significantly reduces risk of major and fatal stroke in patients with symptomatic, high-grade (70-99%) carotid stenosis.

Original Date of Publication: August 15, 1991

Study Rundown: The NASCET was one of the first trials to provide strong evidence in favor of carotid endarterectomy, in addition to medical therapy, in treating symptomatic carotid artery stenosis. The trial demonstrated significant benefits for patients suffering from high-grade carotid stenosis (70-99%), who had recently experienced transient ischemic attack, monocular blindness, or non-disabling stroke. These findings were consistent with findings from the European Carotid Stenosis Trial. At the time, questions remained regarding the benefits of carotid endarterectomy in patients with asymptomatic carotid stenosis, and this has been explored in subsequent trials.

In sum, carotid endarterectomy in addition to medical therapy significantly reduces the absolute risk of ipsilateral stroke and major or fatal ipsilateral stroke in patients with high-grade, symptomatic, carotid artery stenosis.

Please click to read study in NEJM

In-Depth [randomized, controlled study]: The North American Symptomatic Carotid Endarterectomy Trial (NASCET), originally published in NEJM in 1991, explored the use of carotid endarterectomy in managing patients with symptomatic carotid artery stenosis. The trial was conceived in response to the rising rates of carotid endarterectomy without strong evidence to support its use in prophylaxis against cerebrovascular events. Patients were recruited from 50 centres across Canada and the United States and randomized to either medical therapy alone (i.e., antiplatelet, antihypertensive, antilipid, antidiabetic therapy, as needed), or medical therapy with carotid endarterectomy. Patients were eligible for the trial if they provided informed consent, were less than 80 years old, and had a cerebrovascular event (i.e., transient ischemic attack, monocular blindness, non-disabling stroke) in the previous 120 days with ipsilateral carotid stenosis of 30-99% (as per carotid ultrasonography). Patients were assessed at 30 days, every three months for the first year, and every four months subsequently for death or stroke.

The trial was stopped prematurely by the monitoring and executive committees according to a pre-planned rule because of evidence demonstrating treatment efficacy in patients with high-grade stenosis (70-99%) undergoing endarterectomy. The trial involving medium-grade stenosis (30-69%) continued. A total of 659 patients with high-grade stenosis were part of the final analyses. At two years, there was a significant reduction in the absolute risk of ipsilateral stroke by 17% (±3.5%, P<0.001) and major or fatal ipsilateral stroke by 10.6% (±2.6%, P<0.001).

By Adrienne Cheung, Andrew Cheung, M.D.

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