Anticoagulation of cardiomyopathy in children.

Objectives: Cardiomyopathy is a common cause of heart failure in children. Thrombosis is a potential significant secondary complication. Thus warfarin is recommended by the American College of Chest Physicians for the treatment of children with cardiomyopathy despite the lack of published evidence to support its use.

Methods: A retrospective clinical audit to estimate the rates of major bleeding and incidence of thromboembolism associated with oral anticoagulant therapy (warfarin) for primary thromboprophylaxis in a cohort of children with cardiomyopathy. Relevant outcomes including thrombosis and major haemorrhage were defined a priori according to internationally accepted definitions.

Results: 36 children (35.9 warfarin years) were examined, with 25% taking warfarin for greater than 1year. Primary reasons for discontinuation of warfarin therapy were cardiac transplantation (n=7), transition to VAD (n=1), improved cardiac function (n=17), transfer of care (n=3), change to aspirin (n=2). The mean age at starting warfarin was 5.4years (range 0.2-15.2). The most common Target Therapeutic Range (TTR) for warfarin therapy was 2.0 - 3.0. TTR achievement was normally distributed and occurred in a mean 48.5% of all INR tests. There were zero warfarin related adverse events, including thrombosis or haemorrhage.

Conclusion: The low rate of TTR achievement is consistent with previously reported TTR achievement rates for infants. In addition the low rate of TTR achievement was likely influenced by the clinical profile of this complicated condition in children. Nonetheless, this data shows that the clinical outcomes for this cohort are acceptable and warfarin therapy can be safe in children with cardiomyopathy.