title: Reduced-dose warfarin or interrupted warfarin with heparin bridging for pacemaker or defibrillator implantation: a randomized trial.
abstract: BACKGROUND
  Perioperative management with reduced-dose warfarin is of potential interest by eliminating the need for bridging while still maintaining a degree of anticoagulation. The outcomes of this regimen have not been well determined.
  
  
  METHODS
  In a randomized controlled trial we compared two regimens for management of anticoagulation with warfarin in patients with implantation of a pacemaker or defibrillator. Half dose of warfarin for 3-6 days, depending on the baseline international normalized ratio (INR), before surgery aiming at an INR of ≤ 1.7 was compared with interrupted warfarin for 5 days with preoperative bridging with low-molecular-weight heparin (LMWH) at therapeutic dose for 2.5 days. Main safety outcome was pocket hematoma. Secondary outcomes were major bleeding, thromboembolism - all within 1 month, days of hospitalization and number of patients requiring correction of INR with vitamin K.
  
  
  RESULTS
  The study was planned for 450 patients but it was discontinued prematurely due to a change in practice. Pocket hematoma occurred in 4 of 85 patients (5%) randomized to the bridged regimen and in 3 of 86 patients (3%) randomized to reduced-dose warfarin. One pocket hematoma in each group was severe. There were no major hemorrhages or thromboembolism within the 1-month window. Duration of hospitalization was similar in the two groups. Correction of INR the day before surgery with vitamin K had to be used for significantly more patients in the reduced-dose warfarin group (41%) than in the bridged regimen group (6%).
  
  
  CONCLUSIONS
  The reduced-dose warfarin regimen appeared to have similar safety after device implantation as interrupted warfarin with preoperative LMWH bridging. Due to premature discontinuation no firm conclusion can be drawn. The reduced-dose warfarin regimen often failed to achieve the intended preoperative INR. ClinicalTrials.gov Identifier: NCT 02094157.
authors.affiliation: Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, ON, Canada; Department of Medicine, Thrombosis Service, McMaster University, Hamilton, ON, Canada; Karolinska Institutet, Stockholm, Sweden. Electronic address: schulms@mcmaster.ca.
authors.forename: S
authors.initials: S
authors.lastname: Schulman
authors.affiliation: Department of Medicine, Thrombosis Service, McMaster University, Hamilton, ON, Canada; Arrhythmia Services, Cardiology Division, McMaster University, Hamilton, ON, Canada; Population Health Research Institute, McMaster University, Hamilton, ON, Canada.
authors.forename: J S
authors.initials: JS
authors.lastname: Healey
authors.affiliation: Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, ON, Canada; Department of Medicine, Thrombosis Service, McMaster University, Hamilton, ON, Canada.
authors.forename: J D
authors.initials: JD
authors.lastname: Douketis
authors.affiliation: Department of Medicine, Thrombosis Service, McMaster University, Hamilton, ON, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Delaney
authors.affiliation: Department of Medicine, Thrombosis Service, McMaster University, Hamilton, ON, Canada; Arrhythmia Services, Cardiology Division, McMaster University, Hamilton, ON, Canada; Population Health Research Institute, McMaster University, Hamilton, ON, Canada.
authors.forename: C A
authors.initials: CA
authors.lastname: Morillo
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D017147:Defibrillators, Implantable; D005260:Female; D006406:Hematoma / Q000139:chemically induced; D006470:Hemorrhage / Q000139:chemically induced; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D010138:Pacemaker, Artificial; D011300:Preoperative Care; D057234:Preoperative Period; D013923:Thromboembolism / Q000517:prevention & control; D014812:Vitamin K / Q000627:therapeutic use; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D014812:Vitamin K; D014859:Warfarin
keywords: Anticoagulation; Atrial fibrillation; Defibrillator; Pacemaker; Surgery