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North American Symptomatic Carotid Endarterectomy Trial. Methods, patient characteristics, and progress
Insights
Carotid endarterectomy benefits symptomatic patients with carotid artery stenosis. This surgical procedure, combined with best medical therapy, reduces stroke and death compared to medical therapy alone.
Area of Science:
- Vascular Surgery
- Neurology
- Clinical Trials
Background:
- Arteriosclerotic stenosis of the carotid artery causes symptoms related to stroke.
- The benefit of surgical intervention versus medical management requires evaluation.
Purpose of the Study:
- To evaluate the benefit of carotid endarterectomy in patients with symptomatic carotid artery stenosis.
- To compare outcomes of best medical therapy alone versus best medical therapy plus carotid endarterectomy.
Main Methods:
- Randomized controlled trial involving 1,212 patients across 50 North American centers.
- Patients received either best medical therapy or best medical therapy plus carotid endarterectomy.
- Outcomes included nonfatal/fatal stroke and death, with detailed adjudication of events.
Main Results:
- 1,212 patients were randomized between 1987 and 1990.
- Low crossover rate (4.2%) between treatment arms.
- Patient characteristics of randomized and non-randomized eligible individuals were similar, supporting generalizability.
Conclusions:
- Carotid endarterectomy, when added to best medical therapy, appears beneficial for symptomatic carotid artery stenosis.
- Findings are generalizable to the studied patient population.
- Ongoing monitoring for benefit or harm in moderate and severe stenosis groups.
Abstract:
Fifty North American centers have combined to evaluate the benefit of carotid endarterectomy in randomized patients who have experienced symptoms related to arteriosclerotic stenosis of the carotid artery and who have received either best medical therapy alone or best medical therapy plus carotid endarterectomy. The outcome events are nonfatal and fatal stroke or death. A three-tier system identifies and adjudicates the type, severity, and location of each stroke and the cause of any death. Data about patients submitted to carotid endarterectomy outside the trial are compiled at the Nonrandomized Data Center at the Mayo Clinic. Between December 27, 1987, and October 1, 1990, 1,212 patients were randomized, 596 to medical therapy, 616 to carotid endarterectomy. Cross-over from the medical to the surgical arm has been low (4.2%). Patients eligible for the trial, but not randomized totaled 1,044; their characteristics were similar to those randomized so that, for the type of symptomatic patient in this study, our conclusions about the benefit of carotid endarterectomy can be generalized. Patients excluded by medical criteria totaled 679. Another 1,591 had carotid endarterectomy, but either lacked the disease under study, were asymptomatic, or received inadequate investigation to meet entry criteria. We set sample size at 1,900 patients, with continuing enrollment. The Monitoring Committee reviews at intervals the confidential analyses performed on the groups with moderate (30-69%) and severe (70-99%) stenosis. Stopping rules will be invoked for one or both groups if unequivocal benefit or harm is identified.