title: A randomized trial comparing heparin initiation 6 h or 24 h after pacemaker or defibrillator implantation.
abstract: OBJECTIVE
  The purpose of this randomized study was to evaluate the prevalence of pocket hematomas in patients treated with heparin 6 h or 24 h after pacemaker or defibrillator implantation.
  
  
  BACKGROUND
  The risks of pocket hematoma and need for evacuation after device implantation have not been defined in patients who require anticoagulation.
  
  
  METHODS
  Forty-nine consecutive patients with an indication for anticoagulation with heparin after implantable defibrillator or pacemaker implantation were randomized to receive intravenous heparin either 6 h (n = 26) or 24 h (n = 23) postoperatively. Both groups also received warfarin on a daily basis starting the evening of surgery. Twenty-eight patients who received postoperative warfarin alone and 115 patients who did not receive anticoagulation were followed up in a study registry.
  
  
  RESULTS
  A pocket hematoma developed in 6 of 26 patients (22%) who were treated with intravenous heparin 6 h postoperatively, as compared with 4 of 23 patients (17%) who were treated with intravenous heparin 24 h postoperatively (p = 0.7). In total, a pocket hematoma developed in 10 of 49 patients (20%) treated with heparin, 1 of 28 patients (4%) treated with warfarin alone and 2 of 115 (2%) patients who received no anticoagulation (p < 0.001).
  
  
  CONCLUSIONS
  Intravenous heparin initiation 6 h or 24 h after pacemaker or defibrillator implantation is associated with a 20% prevalence of pocket hematoma formation. Warfarin therapy or no anticoagulation is associated with only a 2% to 4% risk of pocket hematoma formation.
authors.affiliation: Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0022, USA. michaudg@umich.edu
authors.forename: G F
authors.initials: GF
authors.lastname: Michaud
authors.forename: F
authors.initials: F
authors.lastname: Pelosi
authors.forename: M D
authors.initials: MD
authors.lastname: Noble
authors.forename: B P
authors.initials: BP
authors.lastname: Knight
authors.forename: F
authors.initials: F
authors.lastname: Morady
authors.forename: S A
authors.initials: SA
authors.lastname: Strickberger
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004334:Drug Administration Schedule; D005260:Female; D006406:Hematoma / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control*; D006493:Heparin / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000009:adverse effects*; D015995:Prevalence; D011446:Prospective Studies; D013997:Time Factors; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin; D006493:Heparin