title: Early risk of stroke after a transient ischemic attack in patients with internal carotid artery disease.
abstract: BACKGROUND
  Transient ischemic attacks (TIAs) often herald a stroke, but little is known about the acute natural history of TIAs. Our objective was to quantify the early risk of stroke after a TIA in patients with internal carotid artery disease.
  
  
  METHODS
  Using patient data from the medical arm of the North American Symptomatic Carotid Endarterectomy Trial, we calculated the risk of ipsilateral stroke in the territory of the symptomatic internal carotid artery within 2 and 90 days after a first-recorded hemispheric TIA. We also studied similar outcomes among patients in the trial who had a first-recorded completed hemispheric stroke.
  
  
  RESULTS
  For patients with a first-recorded hemispheric TIA (n = 603), the 90-day risk of ipsilateral stroke was 20.1% (95% confidence interval [CI] 17.0%-23.2%), higher than the 2.3% risk (95% CI 1.0%-3.6%) for patients with a hemispheric stroke (n = 526). The 2-day risks were 5.5% and 0.0%, respectively. Patients with more severe stenosis of the internal carotid artery (> 70%) appeared to be at no greater risk of stroke than patients with lesser degrees of stenosis (adjusted hazard ratio 1.1, 95% CI 0.7-1.7). Infarct on brain imaging (adjusted hazard ratio 2.1, 95% CI 1.5-3.0) and the presence of intracranial major-artery disease (adjusted hazard ratio 1.9, 95% CI 1.3-2.7) doubled the early risk of stroke in patients with a hemispheric TIA.
  
  
  CONCLUSIONS
  Patients who had a hemispheric TIA related to internal carotid artery disease had a high risk of stroke in the first few days after the TIA. Early risk of stroke was not affected by the degree of internal carotid artery stenosis.
authors.affiliation: Department of Community Health Sciences, University of Calgary, Calgary, Alta.
authors.forename: Michael
authors.initials: M
authors.lastname: Eliasziw
authors.forename: James
authors.initials: J
authors.lastname: Kennedy
authors.forename: Michael D
authors.initials: MD
authors.lastname: Hill
authors.forename: Alastair M
authors.initials: AM
authors.lastname: Buchan
authors.forename: Henry J M
authors.initials: HJ
authors.lastname: Barnett
mesh_terms: D000368:Aged; D002340:Carotid Artery Diseases / Q000453:epidemiology* / Q000601:surgery; D002343:Carotid Artery, Internal / Q000473:pathology* / Q000601:surgery; D016894:Endarterectomy, Carotid; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002546:Ischemic Attack, Transient / Q000453:epidemiology* / Q000601:surgery; D008297:Male; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000601:surgery; D016019:Survival Analysis; D013997:Time Factors