The Fontan procedure, while life saving for patients with single-ventricle physiology, is associated with a wide range of long-term complications. In an effort to deal with some of these complications, Fontan conversion surgery has been proposed, aiming to change the Fontan anatomy from classical atriopulmonary connections to the more modern total cavopulmonary connection (TCPC). This approach may reduce the risk of arrhythmias and thromboembolic events (1-4). However, its impact on long-term survival has previously been unknown.
In this retrospective cohort study, 534 adult patients with Fontan palliation were analysed and categorised into three groups: those with an atriopulmonary Fontan (n=199), those who underwent Fontan conversion to TCPC (n=138), and those who had TCPC as their initial Fontan procedure (n=197). The mean age at the time of Fontan conversion was 29 ± 9 years. Patients with an atriopulmonary Fontan had a comparable mean age of 29 ± 9 years, whereas those with TCPC were younger, with a mean age of 24 ± 7 years. Fontan conversion was primarily indicated as a result of atrial arrhythmias, which accounted for 62% of cases. Other indications included Fontan thrombosis in 13.9%, heart failure in 19%, and miscellaneous causes in 9%.

The study found that transplant-free survival over 15 years was similar between patients who underwent Fontan conversion and those with primary TCPC (42% vs. 47%). Even after excluding the 8% operative mortality associated with Fontan conversion, survival rates remained comparable (38% vs. 47%). Multivariable analysis revealed that neither the type of Fontan connection nor the conversion procedure itself was associated with death or the need for transplantation. Instead, the primary predictors of adverse outcomes were older age, hepatorenal dysfunction, heart failure, and elevated Fontan pressures. These comorbidities were more prevalent and severe with increasing age, suggesting that the duration of Fontan physiology is the dominant factor influencing long-term prognosis.

In summary, given the substantial operative risk and lack of survival benefit, the findings of this study suggest that Fontan conversion may not be the optimal strategy for most adults with atriopulmonary Fontan presenting with Fontan failure. End-stage organ dysfunction, heart failure, and elevated Fontan pressures are the suggested primary determinants of mortality or the need for transplantation, rather than the specific type of Fontan procedure. These factors are associated closely with patient age and the duration of Fontan physiology, and are highly relevant for clinical decision-making regarding treatment strategies for patients with failing Fontan circulation.

This clinically relevant study has already proven useful in our own practice, particularly in guiding decisions when the question of Fontan conversion has arisen. It underscores the importance of individualised risk assessment and highlights the need to weigh the long-term consequences of Fontan physiology carefully against the potential benefits of surgical intervention.