Intermediate term thrombotic risk in contemporary total cavo-pulmonary connection for single ventricle circulations

Despite the common occurrence of thrombosis in Fontan circulations, the mid-term thrombotic risk beyond the first two postoperative years is poorly defined especially in total cavo pulmonary Fontan. This study examines the thrombotic incidence and risk beyond the first 2 years after contemporary Fontan surgery. Using a retrospective cohort study design, 89 Fontan patients, 50 male, were included and evaluated with a median of 8.3 years (IQR 6.8-11.4) follow-up. Hospital records were reviewed for known risk factors of thrombosis, thrombotic events, antiplatelet and anticoagulation management, and basic characteristics. Forty seven patients (52%) had a dominant left ventricle, and 28 (32%) had hypoplastic left heart syndrome. Eight patients had thrombotic events post Fontan surgery at a median age of 9 years (IQR 5.6-13), 5.7 (IQR 2.0-9.7) years following surgery, not including events that occurred immediately peri-operatively. Four thrombotic events were intracardiac whereas the remainder were extra-cardiac. There was no significant univariate correlation between thrombosis and the presence of ventricular morphology, pulmonary arterial reconstruction, or type of cavopulmonary anastomosis (lateral tunnel vs. extracardiac conduit). Thrombosis continues to be an important intermediate-term risk even for patients with contemporary Fontan circulations. These results strongly suggest that thrombophilic risk is not dictated purely by vascular pathway and hemodynamic variables. Further investigation into the pathophysiology, individualized risk, and effectiveness of anticoagulation strategies are required in this high risk population.