title: Plaque Echolucency and the Risk of Ischaemic Stroke in Patients with Asymptomatic Carotid Stenosis Within the First Asymptomatic Carotid Surgery Trial (ACST-1).
abstract: On ultrasound, potentially "high risk" carotid plaques may appear echolucent. In this study, whether a confident classification of echolucent plaque was a predictor of future ipsilateral ischaemic stroke in asymptomatic patients randomized to medical therapy in the Asymptomatic Carotid Surgery Trial-1 (ACST-1) was assessed.
  
  
  
  We performed a post-hoc analysis of 814 ACST-1 patients randomized to medical therapy alone with baseline plaque assessment classified as definitely echolucent (> 25% soft plaque) or nonecholucent (< 25% soft plaque). Kaplan-Meier survival curves were used to compare cumulative rates of ipsilateral ischaemic stroke in both groups.
  
  
  
  In the first 5 years after randomization, a significantly higher risk of ipsilateral stroke was observed in patients with definitely echolucent plaques (8.0%; 95% confidence interval [CI] 6.4-9.6) when compared with patients with definitely nonecholucent plaques (3.1%; 95% CI 2.1-4.1; p = .009). After adjustments for other risk factors, plaque echolucency was associated with a 2.5-times increased risk of ipsilateral ischaemic stroke (hazard ratio 2.52; 95% CI 1.20-5.25; p = .014). Use of lipid-lowering therapy was low in both groups during the first 5 years after randomization but rose sharply during years 5-10 of follow-up, and was significantly more likely to be prescribed for patients with echolucent plaques (p = .001). The risk of ipsilateral ischaemic stroke at 10 years was similar for both groups of patients (p = .233).
  
  
  
  Although the numbers of events in this study was low, definite plaque echolucency (> 25% soft plaque) was associated with a higher 5-year ipsilateral stroke risk in ACST-1 and may therefore help to identify patients at increased risk of stroke for whom carotid intervention may be particularly beneficial.
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Level 6 John Radcliffe Hospital, Oxford OX3 9DU, UK; Department of Vascular Surgery, University Medical Center Utrecht, PO Box 85500, Utrecht, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Huibers
authors.affiliation: Department of Vascular Surgery, University Medical Center Utrecht, PO Box 85500, Utrecht, The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: de Borst
authors.affiliation: Clinical Trial Service Unit, Nuffield Department of Population Health, University of Oxford, Richard Doll Building, Old Road Campus, Roosevelt Drive, Oxford OX3 7LF, UK.
authors.forename: R
authors.initials: R
authors.lastname: Bulbulia
authors.affiliation: Clinical Trial Service Unit, Nuffield Department of Population Health, University of Oxford, Richard Doll Building, Old Road Campus, Roosevelt Drive, Oxford OX3 7LF, UK.
authors.forename: H
authors.initials: H
authors.lastname: Pan
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Level 6 John Radcliffe Hospital, Oxford OX3 9DU, UK. Electronic address: alison.halliday@nds.ox.ac.uk.
authors.forename: A
authors.initials: A
authors.lastname: Halliday
mesh_terms: D000368:Aged; D058070:Asymptomatic Diseases; D016893:Carotid Stenosis / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D020521:Stroke / Q000209:etiology*; D014463:Ultrasonography
keywords: Carotid artery stenosis; Carotid echolucency; Carotid ultrasound; Randomized trial; Stroke