title: Are some patients likely to benefit from recombinant tissue-type plasminogen activator for acute ischemic stroke even beyond 3 hours from symptom onset?
abstract: OBJECTIVE
  Recombinant tissue plasminogen activator (rtPA) has been demonstrated to improve outcomes in acute ischemic stroke when delivered within 3 hours of symptom onset. However, the Alteplase Thrombolysis for Acute Noninterventional Therapy in Ischemic Stroke (ATLANTIS B) trial, in which patients were treated mostly between 3 and 5 hours after symptom onset, found no overall benefit from rtPA. We hypothesized that a subgroup of patients at low risk for thrombolysis-related intracranial hemorrhage, identifiable on the basis of pretreatment clinical variables, may benefit even when treated after 3 hours, despite the overall results of the trial.
  
  
  METHODS
  Using an independently derived multivariate model that predicts the risk of thrombolysis-related intracranial hemorrhage in patients receiving tPA for acute myocardial infarction (based on 6 easily obtainable clinical characteristics), we stratified patients in the ATLANTIS B trial into low-, intermediate-, and high-risk tertiles. We examined outcomes in the prespecified low-risk subgroup using a global test of significance across 4 outcome scales.
  
  
  RESULTS
  Despite having a similar average baseline stroke severity and median time to treatment (270 minutes), patients in the prespecified low-risk group (n=194) were significantly less likely to have a symptomatic intracranial hemorrhage than other patients in the trial (2.2% versus 9.2%, P=0.03). Although there was no treatment effect for rtPA in the overall trial, a consistent trend favoring rtPA therapy (a 5% to 12% absolute treatment benefit) was found across 4 different stroke scales in the prespecified low-risk group (P=0.10). The treatment-benefit-by-risk interaction was significant (P=0.03).
  
  
  CONCLUSIONS
  Use of a multivariate index based on clinical variables is a promising approach to assist in the selection of patients with a favorable risk-benefit profile for thrombolytic therapy beyond 3 hours.
authors.affiliation: Division of Clinical Care Research, Tufts-New England Medical Center, Boston, Mass 02111, USA. dkent1@lifespan.org
authors.forename: David M
authors.initials: DM
authors.lastname: Kent
authors.forename: Robin
authors.initials: R
authors.lastname: Ruthazer
authors.forename: Harry P
authors.initials: HP
authors.lastname: Selker
mesh_terms: D000208:Acute Disease; D000368:Aged; D002545:Brain Ischemia / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data; D018450:Disease Progression; D005260:Female; D006801:Humans; D020300:Intracranial Hemorrhages / Q000209:etiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D015999:Multivariate Analysis; D018579:Patient Selection; D011994:Recombinant Proteins / Q000009:adverse effects / Q000627:therapeutic use*; D018570:Risk Assessment; D020521:Stroke / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000009:adverse effects / Q000627:therapeutic use*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D011994:Recombinant Proteins; D010959:Tissue Plasminogen Activator