Thromboprophylaxis in Adults With Atrio-Pulmonary Fontan

Although aspirin has been compared to warfarin for thromboembolic prophylaxis in the general Fontan population, little is known about the optimal preventative strategy for the atriopulmonary right atrium-pulmonary artery [RA-PA]) Fontan particularly.

A retrospective cohort study was performed including adult patients identified in the Ahmanson/UCLA Adult Congenital Heart Disease Center database with a history of RA-PA Fontan and use of either aspirin or warfarin as most recent primary prophylaxis against thromboembolism. Primary outcome was incident thromboembolism, defined as space-occupying lesion on imaging consistent with thrombus within the Fontan or pulmonary arterial circuit. Secondary outcomes were death, transplantation, Fontan conversion, and bleeding requiring either transfusion or invasive intervention. Follow-up was terminated upon achievement of a primary outcome or achievement of a secondary outcome other than bleeding. Kaplan-Meier analysis of freedom from thrombosis was performed.

Twenty-six patients met inclusion criteria. Thirteen (50%) received aspirin as most recent primary prophylaxis and 13 (50%) received warfarin. Tricuspid atresia was the most common underlying diagnosis (42%), followed by double-inlet left ventricle (38%). Median age at Fontan operation was 8.2 years; median age at prophylaxis initiation was 25.9 years. After six years, the aspirin group had 50% ± 35% freedom from thrombosis and the warfarin group 92% ± 8% ( P = .15). Incidences of secondary outcomes were not significantly different between the groups.

In this cohort of long-term Fontan survivors with RA-PA Fontan, the risk of thromboembolic complications is high, especially in those taking aspirin rather than warfarin. Larger studies are needed to confirm these findings.