A study of Thromboprophylaxis in the Australian and New Zealand Fontan population
Document TypePhD thesis
Access StatusThis item is embargoed and will be available on 2021-11-29.
© 2019 Chantal Attard
Background: The Fontan procedure was developed approximately 50 years ago and has become the definitive treatment for children born with single ventricle physiology. Surgical refinement of the Fontan technique and improvements to critical care have led to a dramatic reduction in mortality, with the vast majority of patients expected to live well into adulthood. The reduction in mortality has led to a shift in research efforts in the Fontan population towards defining the long-term expectations and identifying modifiable factors that can reduce Fontan-associated morbidity. Thrombosis and stroke represent important post-Fontan complications. As such, thromboprophylaxis with warfarin or aspirin is accepted as standard of care post-Fontan. However, there is a notable lack of evidence to inform best practice in the setting of thromboprophylaxis for Fontan patients hence, selection of thromboprophylaxis has been largely dependent on institute practice and clinician preference. Objectives: This thesis explores the long-term outcomes and the impact of current thromboprophylaxis practice in the Australian and New Zealand (ANZ) Fontan population. This study compared cerebrovascular injury, bleeding, bone mineral density (BMD) and quality of life (QoL) in Fontan patients receiving warfarin as compared to aspirin. Methods: This was a cross-sectional, multicentre study of the Australian and New-Zealand Fontan (ANZ) population. Participants underwent cerebral magnetic resonance imaging (MRI) to detect the presence of cerebrovascular injury, dual-energy x-ray absorptiometry (DXA) to assess bone mineral density (BMD). Bleeding and quality of life were assessed using validated questionaries (WA-BAT and PedsQL, respectively). Results: 84 participants underwent brain MRI. Stroke was detected in 33 (39%) participants, with only 5 (15%) of those being clinically symptomatic. There was no association between stroke and Fontan type (p value 0.38, CI 0.39- 1.43) or thromboprophylaxis type. Micro- haemorrhage and white matter injury were detected in almost all participants (96% and 86% respectively), regardless of thromboprophylaxis type. BMD was reduced in our cohort (n=120) compared to the general population however, this reduction was greater in participants receiving warfarin than those on aspirin. High rates of bleeding were reported in both warfarin and aspirin groups however, participants on warfarin experienced more epistaxis and ceased anticoagulation more commonly prior to a medical procedure than those on aspirin. QoL was similar between warfarin and aspirin groups; however, higher QoL scores were reported in patients on warfarin therapy with access to home-INR monitoring compared to those on warfarin therapy without home-INR monitoring. Conclusions: This study adds significantly to the current evidence with regard to the potential consequences of warfarin and aspirin therapy, post-Fontan surgery. Specifically, cerebrovascular injury are frequent occurrences in the ANZ Fontan population, regardless of thromboprophylaxis type. No benefit of long-term warfarin prophylaxis could be demonstrated over aspirin; however, this finding needs to be considered in relation to important clinical features such as cardiac function and lung function. Furthermore, the association of reduced bone health in children on warfarin warrants further mechanistic studies.
KeywordsFontan, Single Ventricle, Warfarin, Aspirin, Stroke, Bone Density, Thromboprophylaxis
- Click on "Export Reference in RIS Format" and choose "open with... Endnote".
- Click on "Export Reference in RIS Format". Login to Refworks, go to References => Import References