title: No difference between aspirin and warfarin after extracardiac Fontan in a propensity score analysis of 475 patients.
abstract: OBJECTIVE
  The most effective method of long-term thromboprophylaxis after the Fontan procedure is not clear. We compared the rates of thromboembolic events between patients receiving aspirin and warfarin after an extracardiac conduit Fontan procedure in a bi-national registry.
  
  
  METHODS
  All patients who underwent an extracardiac conduit Fontan procedure from 1997 to 2010 in Australia and New Zealand were identified. Medication status and routine follow-up and echocardiographic data were obtained from all patients. Survival analysis with propensity score matching and adjustment was performed to determine the treatment effect of warfarin compared with that of aspirin beyond the first year of follow-up, after which time patients had settled on their long-term thromboprophylaxis strategy.
  
  
  RESULTS
  Of 570 eligible patients, the data of 475 patients who were regularly followed up without mechanical valve replacement were available for analysis. Long-term thromboprophylaxis consisted of warfarin in 301 patients (63%), aspirin in 157 (33%) and none in 17 (4%). The 10-year rate of freedom from all thromboembolic events was 91% [95% confidence interval (CI) 88-94%]. Thromboembolic events beyond the first year of follow-up occurred in 18 patients (6 on aspirin and 12 on warfarin). After (i) propensity score adjustment and (ii) matching yielding 164 pairs, the hazard rates of thromboembolic events beyond the first year were not statistically different between the warfarin and aspirin groups [(i) hazard ratio (HR) 2.3, 95% CI 0.7-7.4, P = 0.2 and (ii) HR 1.5, 95% CI 0.5-4.7, P = 0.5, respectively].
  
  
  CONCLUSIONS
  No difference in the hazard rates of late thromboembolic events was observed between aspirin and warfarin beyond the first year after the extracardiac conduit Fontan procedure.
authors.affiliation: Department of Cardiac Surgery, Royal Children's Hospital, Melbourne, Australia.|Murdoch Childrens Research Institute, Melbourne, Australia.|Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, Australia.
authors.forename: Ajay J
authors.initials: AJ
authors.lastname: Iyengar
authors.affiliation: Heart Centre for Children, The Children's Hospital at Westmead, Sydney, Australia.|The University of Sydney, Sydney, Australia.
authors.forename: David S
authors.initials: DS
authors.lastname: Winlaw
authors.affiliation: Murdoch Childrens Research Institute, Melbourne, Australia.|Department of Mathematics and Statistics, La Trobe University, Melbourne, Australia.
authors.forename: John C
authors.initials: JC
authors.lastname: Galati
authors.affiliation: Department of Cardiology, Women's and Children's Hospital, Adelaide, Australia.
authors.forename: Gavin R
authors.initials: GR
authors.lastname: Wheaton
authors.affiliation: Green Lane Paediatric and Congenital Cardiac Service, Starship Children's Hospital, Auckland, New Zealand.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Gentles
authors.affiliation: Department of Cardiology, The Royal Melbourne Hospital, Melbourne, Australia.
authors.forename: Leeanne E
authors.initials: LE
authors.lastname: Grigg
authors.affiliation: Paediatric Cardiology, Queensland Paediatric Cardiac Service, Lady Cilento Children's Hospital, Brisbane, Australia.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Justo
authors.affiliation: Adult Congenital Heart Unit, The Prince Charles Hospital, Brisbane, Australia.
authors.forename: Dorothy J
authors.initials: DJ
authors.lastname: Radford
authors.affiliation: Department of Haematology, Royal Children's Hospital, Melbourne, Australia.
authors.forename: Chantal
authors.initials: C
authors.lastname: Attard
authors.affiliation: Murdoch Childrens Research Institute, Melbourne, Australia.|Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, Australia.|Department of Cardiology, Royal Children's Hospital, Melbourne, Australia.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Weintraub
authors.affiliation: Children's Cardiac Centre, Princess Margaret Hospital for Children, Perth, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Bullock
authors.affiliation: Heart Centre for Children, The Children's Hospital at Westmead, Sydney, Australia.|The University of Sydney, Sydney, Australia.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Sholler
authors.affiliation: The University of Sydney, Sydney, Australia.|Department of Cardiology, Royal Prince Alfred Hospital, Sydney, Australia.
authors.forename: David S
authors.initials: DS
authors.lastname: Celermajer
authors.affiliation: Department of Cardiac Surgery, Royal Children's Hospital, Melbourne, Australia yves.dudekem@rch.org.au.|Murdoch Childrens Research Institute, Melbourne, Australia.|Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, Australia.
authors.forename: Yves
authors.initials: Y
authors.lastname: d'Udekem
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D001315:Australia / Q000453:epidemiology; D005260:Female; D018729:Fontan Procedure / Q000009:adverse effects* / Q000379:methods; D006330:Heart Defects, Congenital / Q000453:epidemiology / Q000601:surgery*; D006470:Hemorrhage / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D008134:Long-Term Care / Q000379:methods; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D011182:Postoperative Care / Q000379:methods; D057216:Propensity Score; D012042:Registries; D013923:Thromboembolism / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D016896:Treatment Outcome; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin; D001241:Aspirin
keywords: Aspirin; Congenital heart disease; Fontan procedure; Thromboprophylaxis; Warfarin