Incidence and Outcomes of the Failing Fontan Following Primary and Conversion to Total Cavopulmonary Connection

All articles of this category (opens in new window) Background: While the total cavopulmonary connection (TCPC) embodies a remarkable achievement in treating children with single-ventricle heart defects, recent studies have shown an increasing incidence of Fontan failures. This study aimed to analyze the incidence and outcomes of failing Fontan after TCPC and TCPC conversion. Methods: All patients after TCPC and TCPC conversion at our center between 1994 and 2022 were retrospectively reviewed. Patients who developed failing Fontan after TCPC and TCPC conversion were identified. Freedom from failing Fontan and survival after the onset of failing Fontan to the last follow-up were plotted on a Kaplan–Meier curve. Laboratory data before and after the onset of failing Fontan were evaluated. Results: Among 635 patients after TCPC, 76 (12%) patients developed failing Fontan with a median period of 3.6 (IQR: 1.0–9.9) years, whereas 12 of 19 (63%) TCPC conversion patients developed failing Fontan with a median period of 1.6 (IQR: 0.8–5.8) years. Freedom from failing Fontan was 91.7, 87.0, and 82.2% at 5, 10, and 15 years in patients after TCPC and 47.7, 34.1, and 34.1% at 5, 10, and 15 years in patients after TCPC conversion ( p < 0.001). Survival after the onset of failing Fontan was 72.7, 62.1, and 50.3% at 5, 10, and 15 years in patients after TCPC and 60.0, 52.5, and 42.0% at 5, 10, and 15 years in patients after TCPC conversion ( p = 0.252). Lymphocyte count, zlog value of NT-proBNP, and Fib-4 value at 1 year before onset, at 6 months before onset, at onset of failing Fontan, and at last follow-up were 2.5 (1.4–3.9), 1.7 (1.0–2.4), 1.1 (0.7–1.5), and 0.9 (0.6–1.5) µL, and 2.17 (1.42–2.98), 1.43 (0.87–3.82), 1.38 (0.67–3.61), and 1.70 (1.13–3.02), and 0.06 (0.03–0.25), 0.26 (0.08–0.62), 0.17 (0.07–0.41), and 0.33 (0.15–0.62), respectively. Lymphocytopenia 6 months before the onset ( p = 0.09, HR: 0.29) and Fib-4 at the onset of failing Fontan ( p = 0.016, HR: 173.1) were risk factors for mortality after the onset of failing Fontan. Conclusion: A significantly high incidence of failing Fontan was observed in patients after TCPC conversion, compared to those after primary TCPC. Survival after the onset of the failing Fontan was comparable between patients after TCPC and TCPC conversion. Lymphocyte concentration decreased before the onset of failing Fontan. Lymphocytopenia and Fib-4 might be a marker for predicting survival after the onset of failing Fontan. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany