Effectiveness of carotid endarterectomy for asymptomatic carotid stenosis: design of a clinical trial. Mayo Asymptomatic Carotid Endarterectomy Study Group.

A clinical trial, as described in this report, has been designed to compare the effects of carotid endarterectomy and medical treatment with aspirin for prevention of transient ischemic attack, reversible ischemic neurologic deficit, and ischemic stroke in patients with asymptomatic pressure-significant carotid stenosis. A prospective randomized controlled trial design is being used, and selection of patients with asymptomatic pressure-significant carotid stenosis is based on the results of ocular pneumoplethysmography and either duplex ultrasound scanning or digital subtraction angiography. Patients are randomized to either surgical (carotid endarterectomy) or medical (aspirin, 80 mg/day) treatment, and follow-up assessment is accomplished by return visits and patient questionnaires. A total of 945 patient-years of follow-up will accumulated for each of the medical and surgical groups.