title: Prevention of venous thrombosis by warfarin after permanent transvenous leads implantation in high-risk patients.
abstract: BACKGROUND
  The incidence of venous lesions following transvenous cardiac device implantation is high. Previous implantation of temporary leads ipsilateral to the permanent devices, and a depressed left ventricular ejection fraction have been associated with an increased risk of venous lesions, though the effects of preventive strategies remain controversial. This randomized trial examined the effects of warfarin in the prevention of these complications in high-risk patients.
  
  
  METHODS
  Between February 2004 and September 2007, we studied 101 adults who underwent a first cardiac device implantation, and who had a left ventricular ejection fraction < or =0.40, or a temporary pacing system ipsilateral to the permanent implant, or both. After device implantation, the patients were randomly assigned to warfarin to a target international normalized ratio of 2.0-3.5, or to placebo. Clinical and laboratory evaluations were performed regularly up to 6 months postimplant. Venous lesions were detected at 6 months by digital subtraction venography.
  
  
  RESULTS
  Venous obstructions of various degrees were observed in 46 of the 92 patients (50.0%) who underwent venography. The frequency of venous obstructions was 60.4% in the placebo, versus 38.6% in the warfarin group (P = 0.018), corresponding to an absolute risk reduction of 22% (relative risk = 0.63; 95% confidence interval = 0.013-0.42).
  
  
  CONCLUSIONS
  Warfarin prophylaxis lowered the frequency of venous lesions after transvenous devices implantation in high-risk patients.
authors.affiliation: Heart Institute (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brazil. rcosta@incor.usp.br
authors.forename: Roberto
authors.initials: R
authors.lastname: Costa
authors.forename: Kátia Regina
authors.initials: KR
authors.lastname: Da Silva
authors.forename: Roberto
authors.initials: R
authors.lastname: Rached
authors.forename: Martino
authors.initials: M
authors.lastname: Martinelli Filho
authors.forename: Francisco César
authors.initials: FC
authors.lastname: Carnevale
authors.forename: Luiz Felipe Pinho
authors.initials: LF
authors.lastname: Moreira
authors.forename: Noedir Antonio Groppo
authors.initials: NA
authors.lastname: Stolf
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects; D015897:Comorbidity; D017147:Defibrillators, Implantable / Q000009:adverse effects; D004566:Electrodes / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000009:adverse effects; D010690:Phlebography; D012307:Risk Factors; D016896:Treatment Outcome; D020246:Venous Thrombosis / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D014859:Warfarin / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin