(528) Increased Thrombosis in Children Less Than 6 Months on ECLS Anticoagulated With Bivalirudin

Introduction: Systemic anticoagulation is vital to prevent thrombosis in extracorporeal life support (ECLS) circuits. However, managing bleeding and thrombotic complications remains a significant challenge, with associated morbidity and mortality. Our center has historically used unfractionated heparin as the primary anticoagulant for pediatric ECLS patients, but it has been associated with higher-than-acceptable rates of bleeding complications. Recognizing that bivalirudin has been successfully adopted as a safe alternative at other centers, we implemented a bivalirudin-based anticoagulation protocol to reduce bleeding events.

Methods: Retrospective cohort study for pediatric patients requiring ECLS from January 2017 to June 2024. In February 2024, a bivalirudin based anticoagulant protocol was implemented. Data collected included age, anticoagulant used, bleeding and thrombotic complications, circuit changes and survival.

Results: 211 patients were included. 173 received heparin and 38 received bivalirudin. Most patients were < 6 months old (heparin 65%, bivalirudin 71%). In patients < 6 months, there is a trend towards decreased incidence of CNS hemorrhage in the bivalirudin cohort (10.7% heparin, 7.4% bivalirudin). In patients >6 months, the incidence of CNS hemorrhage decreased from 13.1% (heparin) to 0% (bivalirudin). In patients < 6 months, clotting complications increased in the bivalirudin group compared to the heparin group (p=0.038), including oxygenator failure (1.8% heparin vs 3.7% bivalirudin), cannula clots or thrombosis (0% heparin vs. 7.4% bivalirudin) and CNS infarction (0.9% heparin vs. 3.7% bivalirudin). In patients >6 months old who received bivalirudin, there were no thrombotic complications in our cohort of 11 patients and only 1 patient who had a bleeding complication.

Conclusions: The incidence of CNS hemorrhage decreased in all patients anticoagulated with bivalirudin. Interestingly, there was a trend towards increased numbers of thrombotic events in patients < 6 months of age. This data could support evidence that infants < 6 months need higher starting doses of bivalirudin as well as higher aPTT target ranges compared to older children to mitigate the risk of thrombosis when using bivalirudin. Ongoing enrollment will increase sample size to strengthen these preliminary results.