title: Preoperative white matter lesions are independent predictors of long-term survival after internal carotid endarterectomy.
abstract: BACKGROUND
  Cerebral white matter lesions (WMLs) predict long-term survival of conservatively treated acute stroke patients with etiology other than carotid stenosis. In carotid endarterectomy patients, WMLs are associated with severe carotid stenosis and unstable plaques, with the risk of perioperative complications and with increased 30-day perioperative risk of death. However, no data exist on their effect on postoperative long-term survival, a factor important when considering the net benefit from carotid endarterectomy. Whether this effect is independent of classical risk factors and indications for surgery is not known either. We hypothesized that WMLs could be evaluated from preoperative routine computed tomography (CT) scans and are predictors of postoperative survival, independent of classical cardiovascular risk factors, indication category and degree of carotid stenosis.
  
  
  METHODS
  A total of 353 of 481 (73.4%) consecutive patients subjected to carotid endarterectomy due to different indications, i.e. asymptomatic stenosis (n = 28, 7.9%), amaurosis fugax (n = 52, 14.7%), transient ischemic attack (n = 135, 38.2%) or ischemic stroke (n = 138, 39.1%), from prospective vascular registries during the years 2001-2010 with digital preoperative CT scans, were included in the study. WMLs were rated by a radiologist (Wahlund criteria) in a blinded fashion. Internal carotid artery (ICA) stenoses were angiographically graded (<50, 50-69, 70-99 and 100%). Odds ratios (ORs) and hazard ratios (HRs) are reported (ORs and HRs ≤1 indicate a beneficial effect). The median follow-up time was 67 months (interquartile range 45.5, range 0-129 months). Spearman's rho was used to estimate intraobserver agreement. Binary logistic regression was performed to analyze the association of risk factors with WMLs. Cox regression proportional hazards analysis was used to study the effect of different factors on survival.
  
  
  RESULTS
  WML severity could be assessed with a substantial intraobserver agreement (Spearman's rho 0.843, p < 0.0001). Only age (OR 1.10, 95% CI 1.06-1.15; p < 0.0001 per year), degree of ipsilateral ICA stenosis (OR 2.22, 95% CI 1.08-4.55; p < 0.05 per stenosis grade) and indication category (OR 1.63, 95% CI 1.19-2.24; p < 0.01 per category) remained independently associated with WMLs. Age (HR 1.04, 95% CI 1.01-1.08; p < 0.05 per year), diabetes (HR 1.59, 95% CI 1.01-2.49; p < 0.05), peripheral arterial disease (HR 2.47, 95% CI 1.46-4.15; p < 0.01), degree of ipsilateral ICA stenosis (HR 2.56, 95% CI 1.12-5.87; p < 0.05 per stenosis grade) and WMLs (HR 3.83, 95% CI 1.17-12.5; p < 0.05) remained independently associated with increased long-term mortality.
  
  
  CONCLUSIONS
  WMLs in a preoperative CT scan provide a substantially reliable estimate of postoperative long-term survival of carotid endarterectomy patients independent of currently used criteria, i.e. cardiovascular risk factors, indication category and degree of ipsilateral ICA stenosis.
authors: Department of Vascular Surgery, Tampere University Hospital and Medical School, Surgery, University of Tampere, Tampere, Finland.
authors: Niku
authors: N
authors: Oksala
authors: Heart Center, Department of Vascular Surgery, Kuopio University Hospital, Kuopio, Finland.
authors: Marianne
authors: M
authors: Jaroma
authors: Regional Imaging Unit, Tampere University Hospital, Tampere, Finland.
authors: Juha-Pekka
authors: JP
authors: Pienimäki
authors: Department of Vascular Surgery, Tampere University Hospital and Medical School, Surgery, University of Tampere, Tampere, Finland.
authors: Tommi
authors: T
authors: Kuorilehto
authors: Department of Vascular Surgery, Tampere University Hospital and Medical School, Surgery, University of Tampere, Tampere, Finland.
authors: Teemu
authors: T
authors: Vänttinen
authors: Department of Vascular Surgery, Tampere University Hospital and Medical School, Surgery, University of Tampere, Tampere, Finland.
authors: Antti
authors: A
authors: Lehtomäki
authors: Department of Vascular Surgery, Tampere University Hospital and Medical School, Surgery, University of Tampere, Tampere, Finland.
authors: Veli-Pekka
authors: VP
authors: Suominen
authors: Regional Imaging Unit, Tampere University Hospital, Tampere, Finland.
authors: Prasun
authors: P
authors: Dastidar
authors: Heart Center, Department of Vascular Surgery, Kuopio University Hospital, Kuopio, Finland.
authors: Kimmo
authors: K
authors: Mäkinen
authors: Department of Neurology, Helsinki University Central Hospital, Helsinki, Finland ; Department of Neurological Sciences, University of Helsinki, Helsinki, Finland.
authors: Timo
authors: T
authors: Erkinjuntti
authors: Department of Vascular Surgery, Tampere University Hospital and Medical School, Surgery, University of Tampere, Tampere, Finland.
authors: Juha-Pekka
authors: JP
authors: Salenius
keywords: Carotid artery stenosis; Carotid endarterectomy; White matter lesions