title: Impact of Collateral Status on Successful Revascularization in Endovascular Treatment: A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  Pre-treatment collateral status may be associated with the rates of successful revascularization in acute ischemic stroke patients receiving endovascular treatment (EVT). We conducted a systematic review and meta-analysis to synthesize relevant evidence currently available.
  
  
  METHODS
  Relevant full-text articles published in English since January 1, 2000, reporting associations between collateral status and successful reperfusion and/or recanalization in acute ischemic stroke patients receiving EVT in cohort or case-control studies, or randomized clinical trials, were retrieved through search of PubMed. Study selection, data extraction and study quality assessment were carried out by 2 investigators. Risk ratios (RR) were pooled for good vs. poor collaterals for the outcomes of successful reperfusion and recanalization, based on random-effects models. Subgroup analyses were conducted to explore for potential factors that might interfere with the effects of pre-treatment collateral status on reperfusion by EVT.
  
  
  RESULTS
  In total, 27 studies (2,366 subjects) were included in qualitative analysis, among which 24 studies (2,239 subjects) were quantitatively analyzed. Overall, good pre-treatment collaterals significantly increased the rate of both successful reperfusion (RR 1.28, 95% CI 1.17-1.40; p < 0.001) and recanalization (RR 1.23, 95% CI 1.06-1.42; p = 0.006), as compared with poor collaterals. Subgroup analyses revealed that the effects of collateral status on successful reperfusion by EVT might be different between populations with different ethnicities.
  
  
  CONCLUSIONS
  Good pre-treatment collaterals may enhance the rates of successful reperfusion and recanalization in EVT for acute ischemic stroke. This may partly explain the favorable effects of good pre-treatment collaterals on clinical outcomes of stroke patients receiving EVT. Thus, it would be valuable to assess the collateral status prior to EVT in acute ischemic stroke. But studies are needed to further verify if the positive effects of good collaterals on revascularization by EVT are restricted to certain subgroups of patients.
authors.affiliation: Department of Medicine and Therapeutics, Hong Kong Branch of The Chinese Cochrane Center (CM), Chinese University of Hong Kong, Hong Kong, SAR, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Leng
authors.forename: Hui
authors.initials: H
authors.lastname: Fang
authors.forename: Thomas W H
authors.initials: TW
authors.lastname: Leung
authors.forename: Chen
authors.initials: C
authors.lastname: Mao
authors.forename: Yuming
authors.initials: Y
authors.lastname: Xu
authors.forename: Zhongrong
authors.initials: Z
authors.lastname: Miao
authors.forename: Liping
authors.initials: L
authors.lastname: Liu
authors.forename: K S Lawrence
authors.initials: KS
authors.lastname: Wong
authors.forename: David S
authors.initials: DS
authors.lastname: Liebeskind
mesh_terms: D017130:Angioplasty / Q000379:methods; D002545:Brain Ischemia / Q000150:complications / Q000628:therapy*; D002548:Cerebral Revascularization / Q000379:methods; D002560:Cerebrovascular Circulation; D003097:Collateral Circulation; D057510:Endovascular Procedures / Q000379:methods*; D006801:Humans; D011379:Prognosis; D015424:Reperfusion; D015607:Stents; D020521:Stroke / Q000209:etiology / Q000628:therapy*; D017131:Thrombectomy / Q000379:methods; D015912:Thrombolytic Therapy / Q000379:methods