title: Association of warfarin therapy duration after bioprosthetic aortic valve replacement with risk of mortality, thromboembolic complications, and bleeding.
abstract: BACKGROUND
  The need for anticoagulation after surgical aortic valve replacement (AVR) with biological prostheses is not well examined.
  
  
  OBJECTIVE
  To perform a nationwide study of the association of warfarin treatment with the risk of thromboembolic complications, bleeding incidents, and cardiovascular deaths after bioprosthetic AVR surgery.
  
  
  METHODS
  Through a search in the Danish National Patient Registry, 4075 patients were identified who had bioprosthetic AVR surgery performed between January 1, 1997, and December 31, 2009. Concomitant comorbidity and medication were retrieved. Poisson regression models were used to determine risk.
  
  
  METHODS
  Incidence rate ratios (IRRs) of strokes, thromboembolic events, cardiovascular deaths, and bleeding incidents by discontinuing warfarin as opposed to continued treatment 30 to 89 days, 90 to 179 days, 180 to 364 days, 365 to 729 days, and at least 730 days after surgery.
  
  
  RESULTS
  The median duration of follow-up was 6.57 person-years. Estimated rates of events per 100 person-years in patients not treated with warfarin compared with those treated with warfarin with comparative absolute risk were 7.00 (95% CI, 4.07-12.06) vs 2.69 (95% CI, 1.49-4.87; adjusted IRR, 2.46; 95% CI, 1.09-5.55) for strokes; 13.07 (95% CI, 8.76-19.50) vs 3.97 (95% CI, 2.43-6.48; adjusted IRR, 2.93; 95% CI, 1.54-5.55) for thromboembolic events; 11.86 (95% CI, 7.81-18.01) vs 5.37 (95% CI, 3.54-8.16; adjusted IRR, 2.32; 95% CI, 1.28-4.22) for bleeding incidents; and 31.74 (95% CI, 24.69-40.79) vs 3.83 (95% CI, 2.35-6.25; adjusted IRR, 7.61; 95% CI, 4.37-13.26) for cardiovascular deaths within 30 to 89 days after surgery; and 6.50 (95% CI, 4.67-9.06) vs 2.08 (95% CI, 0.99-4.36; adjusted IRR, 3.51; 95% CI, 1.54-8.03) for cardiovascular deaths within 90 to 179 days after surgery.
  
  
  CONCLUSIONS
  Discontinuation of warfarin treatment within 6 months after bioprosthetic AVR surgery was associated with increased cardiovascular death.
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Niels Andersens Vej 65, 2900 Hellerup, Denmark. c.merie@mail.dk
authors.forename: Charlotte
authors.initials: C
authors.lastname: Mérie
authors.forename: Lars
authors.initials: L
authors.lastname: Køber
authors.forename: Peter
authors.initials: P
authors.lastname: Skov Olsen
authors.forename: Charlotte
authors.initials: C
authors.lastname: Andersson
authors.forename: Gunnar
authors.initials: G
authors.lastname: Gislason
authors.forename: Jan
authors.initials: J
authors.lastname: Skov Jensen
authors.forename: Christian
authors.initials: C
authors.lastname: Torp-Pedersen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage*; D001021:Aortic Valve / Q000601:surgery; D000082882:Bicuspid Aortic Valve Disease; D002318:Cardiovascular Diseases / Q000401:mortality*; D003718:Denmark / Q000453:epidemiology; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006330:Heart Defects, Congenital / Q000601:surgery*; D006349:Heart Valve Diseases / Q000601:surgery*; D019918:Heart Valve Prosthesis Implantation; D006470:Hemorrhage / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012042:Registries / Q000706:statistics & numerical data; D012306:Risk; D020521:Stroke / Q000453:epidemiology; D013923:Thromboembolism / Q000453:epidemiology*; D014859:Warfarin / Q000008:administration & dosage*
chemical_list: D000925:Anticoagulants; D014859:Warfarin