title: Completeness of the circle of Willis and risk of ischemic stroke in patients without cerebrovascular disease.
abstract: BACKGROUND
  We investigated circle of Willis (CoW) completeness in relation to the risk of future ischemic stroke in patients without prior cerebrovascular disease.
  
  
  METHODS
  We included 976 patients with atherosclerotic disease, but no previous TIA/stroke, from the Second Manifestations of ARTerial disease (SMART) study. All patients underwent MR angiography of the CoW. Cox regression was used to determine whether anterior CoW completeness (anterior communicating artery or A1 segments) and posterior CoW completeness (posterior communicating arteries or P1 segments) were related to future stroke, and whether CoW completeness influenced the relation between internal carotid artery (ICA) stenosis/occlusion and future stroke.
  
  
  RESULTS
  Thirty patients (3.1 %) had ischemic stroke after 9.2 ± 3.0 years of follow-up. Twenty-four patients (80 %) had anterior circulation stroke. An incomplete anterior CoW was related to future anterior circulation stroke (HR 2.8 (95 % CI 1.3-6.3); p = 0.01), whereas a one-sided and two-sided incomplete posterior CoW were not (HR 2.2 (95 % CI 0.7-7.1; p = 0.19) and 1.9 (95 % CI 0.6-5.9; p = 0.29), respectively). In stratified analyses, patients with an incomplete anterior CoW had the highest risk of future anterior circulation stroke when they also had a one-sided (HR 7.0 (95 % CI 1.3-38.2; p = 0.02)) or two-sided incomplete posterior CoW (HR 5.4 (95 % CI 1.0-27.8; p = 0.04). CoW completeness did not change the relation between asymptomatic ICA stenosis/occlusion and future ischemic stroke (p = 0.68).
  
  
  CONCLUSIONS
  An incomplete anterior CoW combined with an incomplete posterior CoW is related to future anterior circulation stroke. CoW completeness has no large effect on the relation between asymptomatic ICA stenosis/occlusion and future stroke.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, HP E01.132, 3584 CX, Utrecht, The Netherlands. T.vanSeeters@umcutrecht.nl.
authors.forename: Tom
authors.initials: T
authors.lastname: van Seeters
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, HP E01.132, 3584 CX, Utrecht, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Hendrikse
authors.affiliation: Department of Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Geert Jan
authors.initials: GJ
authors.lastname: Biessels
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, HP E01.132, 3584 CX, Utrecht, The Netherlands.
authors.forename: Birgitta K
authors.initials: BK
authors.lastname: Velthuis
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, HP E01.132, 3584 CX, Utrecht, The Netherlands.
authors.forename: Willem P T M
authors.initials: WP
authors.lastname: Mali
authors.affiliation: Department of Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: L Jaap
authors.initials: LJ
authors.lastname: Kappelle
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: van der Graaf
mesh_terms: D002561:Cerebrovascular Disorders / Q000453:epidemiology* / Q000473:pathology; D002941:Circle of Willis / Q000002:abnormalities* / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D011859:Radiography; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D020521:Stroke / Q000000981:diagnostic imaging* / Q000453:epidemiology*
keywords: Carotid stenosis; Circle of Willis; Ischemic stroke