Status report on the North American symptomatic carotid surgery trial

NASCET randomized patients with focal symptoms related to arteriosclerotic disease manifest by transient or nondisabling ischemic events in the ipsilateral hemisphere or retina. Patients were randomly assigned to receive best medical care including aspirin when tolerated and control of manageable risk factors or the same medical program to which carotid endarterectomy was added. Patients were stratified into those with arteriographic stenosis of 70% or greater or into the moderate category of less than 70% stenosis. Interim analyses after three years disclosed for patients with 70% or more stenosis a clear benefit from surgery. Below 70% there was no indication of benefit nor harm. The entry of patients with severe disease was stopped and the result published. At two years after surgery, 17 strokes are prevented for every 100 patients submitted to the procedure with severe stenosis. It can also be stated that the functional status of the patients in the surgical cohort exceeded that in the patients assigned to medicine. Subgroup analyses noted that: the risk experienced by medical patients with retinal events is only one-third for those with hemisphere events. A definite ulcerative lesion nearly doubles the risk. Age is an important risk factor but surgery benefits those in the later as in the younger decades. Contralateral stenosis adds only slightly to the risk of stroke whereas contralateral occlusion quadruples the risk. Surgical benefit is present despite contralateral occlusion. Silent brain infarctions in CT examinations added to the risk in the medical group compared to those without this phenomenon. Surgery benefited both of these subgroups equally.(ABSTRACT TRUNCATED AT 250 WORDS)