Abstract 2087: Factors Associated With Thrombotic Complications in the First 2 Years After the Fontan Procedure: A Multicentre Prospective Study
Thrombosis (TE) is an important complication for children with single ventricle and Fontan procedure, contributing to mortality and morbidity. Many associated factors have been proposed, but there have been no prospective studies. We performed a multicentre international randomized trial of anticoagulation with aspirin versus heparin/warfarin for a 2 year period after Fontan in children. Primary endpoint was TE, either intracardiac or embolic (all events adjudicated). At 3 months and 2 years after Fontan, a transthoracic and tranesophageal echocardiogram were performed as routine screening. Clinically suspected TE’s were objectively documented. Multivariable multiphase parametric timed-event modeling was used to identify independent factors associated with an increased risk of TE. Of the 111 patients included, the average age at Fontan was 3.8 years. There were 2 deaths (unrelated to TE) and 1 Fontan takedown before the end of the study. Venous TE was noted in 25 pts (23%); there were no arterial TE. Both an early (peak at 1–2 months) and a late (slow rise from 18 months) phase of risk for TE were seen from timed-event modeling. No factors were associated with an increased risk of TE in the late phase. For the early phase of risk, demographic factors associated with higher risk included female gender (odds ratio: 1.30, 95% confidence interval: 1.08 –1.57, p=0.005). Anatomical factors included diagnosis of pulmonary atresia with intact ventricular septum (OR: 1.62 (1.18 –2.22), p=0.003), previous coarctation of the aorta repair (OR: 1.62 (1.08 –2.42), p=0.02) and pulmonary artery distortion (OR: 1.23 (1.02–1.48), p=0.04). Post-operative factors included longer duration of vasodilator infusion (OR: 1.08/10hours (1.03–1.12), p<0.001), use of central venous lines for >10 days or until discharge (OR: 2.35 (1.33– 4.15), p=0.003) and lower inspired FiO2 at 24 hours after Fontan (OR: 0.82 (0.71– 0.95), p=0.008). TE was not associated with previous TE, fenestration, Fontan connection type or treatment assignment. TE remains a prevalent complication after Fontan, with the highest risk in the early post-op period, and is most strongly associated with prolonged use of central lines, despite anticoagulation. More effective strategies are needed.