title: Absence of microemboli on transcranial Doppler identifies low-risk patients with asymptomatic carotid stenosis.
abstract: OBJECTIVE
  Carotid endarterectomy clearly benefits patients with symptomatic severe stenosis (SCS), but the risk of stroke is so low for asymptomatic patients (ACS) that the number needed to treat is very high. We studied transcranial Doppler (TCD) embolus detection as a method for identifying patients at higher risk who would have a lower number needed to treat.
  
  
  METHODS
  Patients with carotid stenosis of > or =60% by Doppler ultrasound who had never been symptomatic (81%) or had been asymptomatic for at least 18 months (19%) were studied with TCD embolus detection for up to 1 hour on 2 occasions a week apart; patients were followed for 2 years.
  
  
  RESULTS
  319 patients were studied, age (standard deviation) 69.68 (9.12) years; 32 (10%) had microemboli at baseline (TCD+). Events were more likely to occur in the first year. Patients with microemboli were much more likely to have microemboli 1 year later (34.4 versus 1.4%; P<0.0001) and were more likely to have a stroke during the first year of follow-up (15.6%, 95% CI, 4.1 to 79; versus 1%, 95% CI, 1.01 to 1.36; P<0.0001).
  
  
  CONCLUSIONS
  Our findings indicate that TCD- ACS will not benefit from endarterectomy or stenting unless it can be done with a risk <1%; TCD+ may benefit as much as SCS if their surgical risk is not higher. These findings suggest that ACS should be managed medically with delay of surgery or stenting until the occurrence of symptoms or emboli.
authors.affiliation: Stroke Prevention & Atherosclerosis Research Centre, Robarts Research Institute, University of Western Ontario, London, Canada. dspence@robarts.ca
authors.forename: J David
authors.initials: JD
authors.lastname: Spence
authors.forename: Arturo
authors.initials: A
authors.lastname: Tamayo
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Lownie
authors.forename: Wai P
authors.initials: WP
authors.lastname: Ng
authors.forename: Gary G
authors.initials: GG
authors.lastname: Ferguson
mesh_terms: D000367:Age Factors; D000368:Aged; D002343:Carotid Artery, Internal / Q000473:pathology; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000473:pathology*; D016894:Endarterectomy, Carotid / Q000379:methods; D005260:Female; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000175:diagnosis* / Q000473:pathology*; D008297:Male; D008833:Microcirculation; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D012306:Risk; D012307:Risk Factors; D020521:Stroke / Q000473:pathology; D013997:Time Factors; D014456:Ulcer / Q000473:pathology; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*