title: Plaque characteristics of asymptomatic carotid stenosis and risk of stroke.
abstract: BACKGROUND
  The optimal treatment of asymptomatic carotid stenosis (ACS) is controversial. To optimize the risk-benefit ratio of carotid artery revascularization, it is crucial to identify ACS patients who are at increased stroke risk. Recent data suggest that plaque vulnerability depends on its composition. Therefore, we assessed plaque composition in ACS to determine predictors for ipsilateral cerebrovascular events.
  
  
  METHODS
  62 patients with 65 ACS ≥50% underwent 3-T MRI of the carotid bifurcation (TOF, special dark-blood weighted noncontrast and contrast-enhanced T(1) and T(2) images) and of the brain. The different plaque components (lipid core, intraplaque hemorrhage, calcification and the status of the fibrous cap) were assessed. Furthermore, the plaque volume and the volume of clinically silent cortical and subcortical infarcts in the territory of the stenosed carotid artery as seen on FLAIR images were determined by using a semi-automated software. Carotid stenosis was considered asymptomatic if there had not been any clinically apparent ischemic events in the corresponding vascular territory within the previous 6 months. During follow-up, information on the occurrence of cerebrovascular events, medical treatment and sonographic changes of the stenosis was collected.
  
  
  RESULTS
  At baseline, 24 ACS (37%) were classified as high grade. A lipid-rich necrotic core was the dominant plaque component in 16 ACS (25%). The plaque volume was higher in ACS with a lipid-rich necrotic core as dominant plaque component (p = 0.002) and in patients with prior stroke/TIA (p = 0.010). After a median follow-up of 18.9 months (interquartile range 3.5-30.1) there were 2 ipsilateral strokes and 3 ipsilateral TIAs. The average annual event rate was 7.7%. A lipid-rich necrotic core (HR 7.21; 95% CI 1.12-46.28; p = 0.037), sonographic progression of the stenosis (HR 7.00; 95% CI 1.13-41.34; p = 0.036), history of stroke (HR 11.03; 95% CI 1.23-99.36; p = 0.032), and the volume of clinically asymptomatic ischemic brain lesions (HR 1.14/cm(3); 95% CI 1.03-1.25; p = 0.008) predicted cerebrovascular events. Patients on statin therapy at follow-up were at lower risk of events (HR 0.17; 95% CI 0.03-1.00; p = 0.05).
  
  
  CONCLUSIONS
  In addition to medical history and sonographic findings, a lipid-rich necrotic core within the plaque turned out as a predictor of cerebrovascular events. Therefore, MR imaging of carotid plaques deserves further attention and might be helpful to improve risk stratification of asymptomatic carotid disease. The identified predictors could be combined in a risk model and tested in larger prospective studies.
authors.affiliation: Department of Neurology, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Marie-Luise
authors.initials: ML
authors.lastname: Mono
authors.forename: Alexander
authors.initials: A
authors.lastname: Karameshev
authors.forename: Johannes
authors.initials: J
authors.lastname: Slotboom
authors.forename: Luca
authors.initials: L
authors.lastname: Remonda
authors.forename: Aekaterini
authors.initials: A
authors.lastname: Galimanis
authors.forename: Simon
authors.initials: S
authors.lastname: Jung
authors.forename: Oliver
authors.initials: O
authors.lastname: Findling
authors.forename: Gian Marco
authors.initials: GM
authors.lastname: De Marchis
authors.forename: Rudolf
authors.initials: R
authors.lastname: Luedi
authors.forename: Claus
authors.initials: C
authors.lastname: Kiefer
authors.forename: Carole
authors.initials: C
authors.lastname: Stuker
authors.forename: Heinrich P
authors.initials: HP
authors.lastname: Mattle
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schroth
authors.forename: Marcel
authors.initials: M
authors.lastname: Arnold
authors.forename: Krassen
authors.initials: K
authors.lastname: Nedeltchev
authors.forename: Marwan
authors.initials: M
authors.lastname: El-Koussy
mesh_terms: D000368:Aged; D002339:Carotid Arteries / Q000473:pathology*; D016893:Carotid Stenosis / Q000150:complications / Q000473:pathology*; D005260:Female; D006470:Hemorrhage / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000175:diagnosis / Q000473:pathology*; D011446:Prospective Studies; D012307:Risk Factors; D020521:Stroke / Q000473:pathology*