Prognosis after transient monocular blindness associated with carotid-artery stenosis

Background: Transient monocular blindness associated with internal-carotid- artery stenosis is a risk factor for stroke. The effect of carotid endarter ectomy in patients who present with transient monocular blindness has not b een determined. Methods: We compared the risk of stroke among patients presenting with tran sient monocular blindness with the risk among patients presenting with hemi spheric transient ischemic attack. The effect of endarterectomy was assesse d in patients with transient monocular blindness. The analyses were based o n data from the North American Symptomatic Carotid Endarterectomy Trial. Results: A total of 198 medically treated patients with transient monocular blindness had a three-year risk of ipsilateral stroke that was approximate ly half of that among 417 medically treated patients with hemispheric trans ient ischemic attack (adjusted hazard ratio, 0.53; 95 percent confidence in terval, 0.30 to 0.94). Six factors were associated with a higher risk of st roke in patients with monocular blindness -- an age of 75 years or more, ma le sex, a history of hemispheric transient ischemic attack or stroke, a his tory of intermittent claudication, stenosis of 80 to 94 percent of the lumi nal diameter, and the absence of collateral circulation. The three-year ris k of stroke with medical treatment for patients with zero or one risk facto r was 1.8 percent, with two risk factors 12.3 percent, and with three or mo re risk factors 24.2 percent (P=0.003). The three-year absolute reduction i n the risk of stroke associated with endarterectomy was -2.2 percent (i.e., a 2.2 percent increase in risk) among patients with zero or one risk facto r, 4.9 percent among those with two risk factors, and 14.3 percent among th ose with three or more risk factors (P=0.23 by a test for interaction). Conclusions: Among patients with internal-carotid-artery stenosis, the prog nosis was better for those presenting with transient monocular blindness th an for those presenting with hemispheric transient ischemic attack. Among p atients with transient monocular blindness, carotid endarterectomy may be b eneficial when other risk factors for stroke are also present. (N Engl J Me d 2001;345:1084-90.) Copyright (C) Massachusetts Medical Society.