title: Low-molecular-weight heparin vs heparin in the treatment of patients with pulmonary embolism. American-Canadian Thrombosis Study Group.
abstract: BACKGROUND
  Pulmonary embolism (PE) occurs in 50% or more of patients with proximal deep-vein thrombosis. Low-molecular-weight heparin treatment is effective and safe in patients with deep vein thrombosis and may also be so in patients with PE. Recent rigorous clinical trials have established objective criteria for determining a high probability of PE by perfusion lung scanning.
  
  
  OBJECTIVE
  To compare low-molecular-weight heparin with intravenous heparin for the treatment of patients with objectively documented PE and underlying proximal deep vein thrombosis.
  
  
  METHODS
  In a multicenter, double-blind, randomized trial, we compared fixed-dose subcutaneous low-molecular-weight heparin (tinzaparin sodium) given once daily with dose-adjusted intravenous heparin given by continuous infusion using objective documentation of clinical outcomes. Pulmonary embolism at study entry was documented by the presence of high-probability lung scan findings.
  
  
  RESULTS
  Of 200 patients with high-probability lung scan findings at study entry, none of the 97 who received low-molecular-weight heparin had new episodes of venous thromboembolism compared with 7 (6.8%) of 103 patients who received intravenous heparin (95% confidence interval for the difference, 1.9%-11.7%; P = .01). Major bleeding associated with initial therapy occurred in 1 patient (1.0%) who was given low-molecular-weight heparin and in 2 patients (1.9%) given intravenous heparin (95% confidence interval for the difference, -2.4% to 4.3%).
  
  
  CONCLUSIONS
  Low-molecular-weight heparin administered once daily subcutaneously was no less effective and probably more effective than use of dose-adjusted intravenous unfractionated heparin for preventing recurrent venous thromboembolism in patients with PE and associated proximal deep vein thrombosis. Our findings extend the use of low-molecular-weight heparin without anticoagulant monitoring to patients with submassive PE.
authors.affiliation: Department of Community Health Sciences, University of Calgary, Alberta, Canada. jeanne.sheldon@CRHA-Health.ab.ca
authors.forename: R D
authors.initials: RD
authors.lastname: Hull
authors.forename: G E
authors.initials: GE
authors.lastname: Raskob
authors.forename: R F
authors.initials: RF
authors.lastname: Brant
authors.forename: G F
authors.initials: GF
authors.lastname: Pineo
authors.forename: G
authors.initials: G
authors.lastname: Elliott
authors.forename: P D
authors.initials: PD
authors.lastname: Stein
authors.forename: A
authors.initials: A
authors.lastname: Gottschalk
authors.forename: K A
authors.initials: KA
authors.lastname: Valentine
authors.forename: A F
authors.initials: AF
authors.lastname: Mah
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D002170:Canada; D004311:Double-Blind Method; D005260:Female; D006493:Heparin / Q000008:administration & dosage*; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage*; D006801:Humans; D007262:Infusions, Intravenous; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000188:drug therapy* / Q000209:etiology; D016896:Treatment Outcome; D014481:United States; D020246:Venous Thrombosis / Q000150:complications
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D006493:Heparin