THE RISK OF STROKE IN PATIENTS WITH FIRST-EVER RETINAL VS HEMISPHERICTRANSIENT ISCHEMIC ATTACKS AND HIGH-GRADE CAROTID STENOSIS

Background: The prognosis of amaurosis fugax has been considered to be favorable compared with that of hemispheric transient ischemic attack s. However, this has remained uncertain for patients with significant carotid stenosis as the assessment of progression of the disease has b een confounded When patients undergo carotid endarterectomy. In the No rth American Symptomatic Carotid Endarterectomy Trial, patients with h igh-grade (70% to 99%) carotid stenosis were randomized to receive eit her medical or surgical treatment, thus making an unconfounded analysi s possible. Method: we identified 129 medically treated patients with high-grade carotid stenosis who had their first-ever transient ischemi c attack as the entry event into the trial. Fifty-nine patients with r etinal transient ischemic attacks (RTIAs) were compared with 70 patien ts with hemispheric transient ischemic attacks (HTIAs). Results: Patie nts with HTIAs were older, with a higher prevalence of most risk facto rs for stroke. Average time of delay from the onset of transient ische mic attacks to medical treatment was longer for patients with RTIAs th an for patients with HTIAs (48.5 vs 15.2 days). Kaplan-Meier estimates of the risk of ipsilateral. stroke at 2 years were 16.6% +/- 5.6% for patients with RTIAs and 43.5% +/- 6.7% for patients with HTIAs (P = . 002 for the difference in risk between RTIAs and HTIAs). From correspo nding Cox's proportional hazards regression analyses, the risk of ipsi lateral stroke ranged from 11.2% to 28.9% for patients with RTIAs and from 37.4% to 96.3% for patients with HTIAs across stenoses, spanning 75% to 95%. Overall, the relative risk of ipsilateral stroke (HTLAs co mpared with RTIAs) was 3.23 (95% confidence interval, 1.47 to 7.12), r egardless of the degree of high-grade stenosis. Conclusion: To our kno wledge, this study is the first report on the expected outcome for med ically treated patients with high-grade (70% to 99%) carotid stenosis in whom the first-ever event was either an RTIA or HTIA. The presence of RTIAs carries a considerable risk of ipsilateral strokes, particula rly at higher degrees of stenosis. However, in comparison with HTIAs, patients with RTIAs still have a better prognosis.