Primary Findings From Selected Recent National Institute of Neurological Disorders and Stroke-Sponsored Clinical Trials That Have shaped Modern Stroke Prevention

NORTH AMERICAN SYMPTOMATIC CAROTID ENDARTERECTOMY TRIAL The North American Symptomatic Carotid Endarterectomy Trial (NASCET) answered practical questions relating to the efficacy and safety of carotid endarterectomy based on degree of carotid stenosis and accompanying medical comorbidity in patients with symptomatic carotid stenosis (The Canadian Cooperative Study Group, 1998; North American Symptomatic Carotid Endarterectomy Trial Collaborators, 1991). In summary, key findings were that carotid endarterectomy resulted in benefits for the following three outcomes among persons with 70% to 99% symptomatic carotid stenosis when compared with medical management alone: (1) ipsilateral stroke, (2) major or fatal ipsilateral stroke, or (3) stroke or death. However, the surgical risks outweighed any benefits among those with less than 50% symptomatic carotid stenosis. For those with severe carotid stenosis (70% or greater), the surgical treatment group experienced durable benefit at 8 years. For those with 50% to 69% symptomatic carotid stenosis, the benefits were more modest but, again, in favor of surgical treatment. Patients in the 50% to 69% treatment group with hemispheral cerebrovascular symptoms and those who were men had greater benefit from surgery than those who had retinal ischemic symptoms or who were women. Medical and surgical complications in NASCET were reviewed previously (Ferguson et al, 1999; Paciaroni et al, 1999).