The clinical course of carotid bifurcation stenosis as determined by duplex scanning.

Two hundred three patients had at least two carotid artery duplex (DS) examinations separated by at least 6 months (mean follow-up 18 months) and their risk factors, clinical outcome, and degree of carotid artery stenosis were compared. The accuracy of DS was established at greater than 90% by blinded comparison with angiography. During the study period 138 patients (68%) had stable carotid artery stenosis and 65 patients (32%) had progression of stenosis in at least one artery. Thirty patients had new symptoms of cerebrovascular disease (19 with transient ischemic attacks and 11 with stroke) during the study. It was not possible to predict which patients would become symptomatic on the basis of risk factor analysis or analysis of severity of stable carotid stenosis. Patients with progression of carotid artery stenosis to greater than 50% diameter reduction were significantly more likely (p less than 0.0001) to have new transient ischemic attack and stroke than were those with stable carotid artery stenosis, regardless of severity.