title: A therapeutic window for carotid endarterectomy in patients with asymptomatic carotid stenosis.
abstract: The natural history of asymptomatic carotid stenosis was prospectively and systematically studied in 500 patients by clinical observation and carotid Doppler ultrasonography. In the 40% of carotid arteries (398) with an initial stenosis of over 35%, there were apparently two separate populations, with a cutoff point of 85% stenosis. There were 79 ischemic cerebral events (54 transient ischemic attacks and 25 strokes) among the 500 patients during 60 months of follow-up, predominantly in the severe-stenosis (more than 75%) group, with few events occurring in the near-or total-occlusion (95% to 100% stenosis) group; the highest incidence was in patients whose arteries had 75% to 90% stenosis. These observations indicate a critical degree of carotid stenosis at which stroke risk becomes maximal, declining as the artery becomes occluded. These findings suggest that there may be a "window" for carotid endarterectomy in patients with asymptomatic carotid stenosis, when the stroke risk may be high enough (5.5%/year) to warrant surgery.
authors.affiliation: Stroke Research Unit, Sunnybrook Health Science Centre, University of Toronto, Ont.
authors.forename: C Z
authors.initials: CZ
authors.lastname: Zhu
authors.forename: J W
authors.initials: JW
authors.lastname: Norris
mesh_terms: D001314:Auscultation; D016893:Carotid Stenosis / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D002561:Cerebrovascular Disorders / Q000209:etiology / Q000517:prevention & control; D016894:Endarterectomy, Carotid; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002546:Ischemic Attack, Transient / Q000209:etiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D014463:Ultrasonography