title: Low molecular weight heparin decreases rebound ischemia in unstable angina or non-Q-wave myocardial infarction: the Canadian ESSENCE ST segment monitoring substudy.
abstract: OBJECTIVE
  The goal of this study was to determine whether enoxaparin was more effective than heparin in reducing recurrent ischemic episodes.
  
  
  BACKGROUND
  Continuous ST segment monitoring is a simple tool for assessment of ischemia and identifies patients with a worse prognosis. Little is known about the impact of low molecular weight heparin on ST segment shift.
  
  
  METHODS
  Patients were randomized to receive enoxaparin or heparin (mean 3.4 days). Three-lead ST segment monitoring was performed for the first 48 h (n = 220) and an additional 48 h (n = 174) after intravenous study drug discontinuation (mean 1.9 days later).
  
  
  RESULTS
  During initial monitoring, ischemia rates were similar among the heparin and enoxaparin groups (27.2% vs. 22.6%, p = 0.44); however, the time to first ischemic episode was earlier among heparin-treated patients (11 +/- 11 vs. 25 +/- 18 min, p = 0.001). After drug discontinuation, ischemic episodes occurred more frequently (44.6% vs. 25.6%, p = 0.009), and the total ischemic duration was greater among heparin patients (18 +/- 39 vs. 5 +/- 12 min/24 h, p = 0.005). Recurrent ischemia occurred more frequently after discontinuation in the heparin (46% vs. 31%, p = 0.043), but not the enoxaparin, group (18.4% vs. 25%, p = 0.33). Regardless of treatment, patients with ischemia were more likely to die or experience (re)infarction at one year (18.4% vs. 8.3%, p = 0.023).
  
  
  CONCLUSIONS
  ST segment shift occurs frequently in unstable angina/non-Q-wave myocardial infarction despite antithrombotic therapy and is associated with worse one-year prognosis. Enoxaparin is a more effective antithrombotic treatment than unfractionated heparin and leads to greater prevention of rebound ischemia.
authors.affiliation: Canadian Heart Research Center, Division of Cardiology, St Michael's Hospital, University of Toronto, Ontario. goodmans@smh.toronto.on.ca
authors.forename: S G
authors.initials: SG
authors.lastname: Goodman
authors.forename: A
authors.initials: A
authors.lastname: Barr
authors.forename: A
authors.initials: A
authors.lastname: Sobtchouk
authors.forename: M
authors.initials: M
authors.lastname: Cohen
authors.forename: G J
authors.initials: GJ
authors.lastname: Fromell
authors.forename: L
authors.initials: L
authors.lastname: Laperrière
authors.forename: C
authors.initials: C
authors.lastname: Hill
authors.forename: A
authors.initials: A
authors.lastname: Langer
mesh_terms: D000368:Aged; D000789:Angina, Unstable / Q000150:complications* / Q000401:mortality / Q000503:physiopathology; D004562:Electrocardiography; D017984:Enoxaparin / Q000627:therapeutic use*; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000401:mortality / Q000503:physiopathology; D017202:Myocardial Ischemia / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control*; D012008:Recurrence; D015996:Survival Rate; D013997:Time Factors
chemical_list: D017984:Enoxaparin; D005343:Fibrinolytic Agents