title: Asymptomatic internal carotid artery stenosis and cerebrovascular risk stratification.
abstract: BACKGROUND
  The purpose of this study was to determine the cerebrovascular risk stratification potential of baseline degree of stenosis, clinical features, and ultrasonic plaque characteristics in patients with asymptomatic internal carotid artery (ICA) stenosis.
  
  
  METHODS
  This was a prospective, multicenter, cohort study of patients undergoing medical intervention for vascular disease. Hazard ratios for ICA stenosis, clinical features, and plaque texture features associated with ipsilateral cerebrovascular or retinal ischemic (CORI) events were calculated using proportional hazards models.
  
  
  RESULTS
  A total of 1121 patients with 50% to 99% asymptomatic ICA stenosis in relation to the bulb (European Carotid Surgery Trial [ECST] method) were followed-up for 6 to 96 months (mean, 48). A total of 130 ipsilateral CORI events occurred. Severity of stenosis, age, systolic blood pressure, increased serum creatinine, smoking history of more than 10 pack-years, history of contralateral transient ischemic attacks (TIAs) or stroke, low grayscale median (GSM), increased plaque area, plaque types 1, 2, and 3, and the presence of discrete white areas (DWAs) without acoustic shadowing were associated with increased risk. Receiver operating characteristic (ROC) curves were constructed for predicted risk versus observed CORI events as a measure of model validity. The areas under the ROC curves for a model of stenosis alone, a model of stenosis combined with clinical features and a model of stenosis combined with clinical, and plaque features were 0.59 (95% confidence interval [CI] 0.54-0.64), 0.66 (0.62-0.72), and 0.82 (0.78-0.86), respectively. In the last model, stenosis, history of contralateral TIAs or stroke, GSM, plaque area, and DWAs were independent predictors of ipsilateral CORI events. Combinations of these could stratify patients into different levels of risk for ipsilateral CORI and stroke, with predicted risk close to observed risk. Of the 923 patients with ≥ 70% stenosis, the predicted cumulative 5-year stroke rate was <5% in 495, 5% to 9.9% in 202, 10% to 19.9% in 142, and ≥ 20% in 84 patients.
  
  
  CONCLUSIONS
  Cerebrovascular risk stratification is possible using a combination of clinical and ultrasonic plaque features. These findings need to be validated in additional prospective studies of patients receiving optimal medical intervention alone.
authors.affiliation: Department of Vascular Surgery, Imperial College, London, United Kingdom. andisnicolai@gmail.com
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Nicolaides
authors.forename: Stavros K
authors.initials: SK
authors.lastname: Kakkos
authors.forename: Efthyvoulos
authors.initials: E
authors.lastname: Kyriacou
authors.forename: Maura
authors.initials: M
authors.lastname: Griffin
authors.forename: Michael
authors.initials: M
authors.lastname: Sabetai
authors.forename: Dafydd J
authors.initials: DJ
authors.lastname: Thomas
authors.forename: Thomas
authors.initials: T
authors.lastname: Tegos
authors.forename: George
authors.initials: G
authors.lastname: Geroulakos
authors.forename: Nicos
authors.initials: N
authors.lastname: Labropoulos
authors.forename: Caroline J
authors.initials: CJ
authors.lastname: Doré
authors.forename: Tim P
authors.initials: TP
authors.lastname: Morris
authors.forename: Ross
authors.initials: R
authors.lastname: Naylor
authors.forename: Anne L
authors.initials: AL
authors.lastname: Abbott
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020757:Amaurosis Fugax / Q000209:etiology; D002545:Brain Ischemia / Q000209:etiology; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging; D016893:Carotid Stenosis / Q000150:complications* / Q000175:diagnosis / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D018570:Risk Assessment; D020521:Stroke / Q000209:etiology*; D014463:Ultrasonography