Early Thromboprophylaxis Initiation is Associated With Reduced Fontan Thromboses in the Early Postoperative Period

Fontan circuit thrombosis is a significant cause of early postoperative morbidity and mortality. Thrombosis incidence and relationship to thromboprophylaxis choice and timing of initiation are not well established. We sought to evaluate the incidence of Fontan circuit thrombosis in the first 30 postoperative days and its relationship to thromboprophylaxis choice and timing. Patients undergoing Fontan surgery, 2006-2016, were reviewed. Fontan circuit thrombosis was defined by sonographic detection of intracardiac or deep venous thrombi. Logistic regression was used to assess relationships between thromboprophylaxis characteristics and thrombosis. One hundred ninety-two patients underwent Fontan. Fontan thrombosis occurred in 19 (10%) patients. 54% were started on aspirin, 27% coumadin, 4% heparin, and 7% none. There was no relationship between thrombosis and baseline anatomy, Fontan type or fenestration. Median time to thromboprophylaxis initiation was 4 days (interquartile range 2-6). Patients not started on thromboprophylaxis had 44.8 times the odds of thrombosis as those on thromboprophylaxis (confidence interval 6.4-311.7, P < 0.01); no children starting thromboprophylaxis before postoperative day 2 developed thromboses. For every day that thromboprophylaxis was delayed, odds of thrombosis increased by 30% (odds ratio 1.3; CI 1.1-1.6, P < 0.01). There was no difference in the odds of thrombosis between children taking aspirin vs other thromboprophylaxis types. Odds of early postoperative Fontan circuit thrombosis are increased in patients in whom thromboprophylaxis is delayed beyond the second postoperative day, with no difference in the odds of thrombosis between patients initiated on aspirin vs other thromboprophylaxis. Early aspirin institution post Fontan is recommended to reduce morbidity. Ultra-mini-Abstract: Odds of early postoperative Fontan circuit thrombosis are increased in patients in whom thromboprophylaxis is delayed beyond the second postoperative day, with no difference in the odds of thrombosis between patients initiated on aspirin vs other thromboprophylaxis. Early aspirin institution post Fontan is recommended to reduce morbidity and resource utilization.