Patients with Fontan circulation exhibit lower exercise capacity than their normal healthy peers, which is strongly associated with high morbidity and mortality (1). Thus, exercise training could be one of the therapeutic strategies, and several studies with exercise interventions have been conducted and the beneficial effect of improving exercise capacity has been demonstrated (2). On the other hand, Fontan patients with normal exercise capacity (≥80% predicted normal value) have been defined as “Super-Fontan (SF)” (3); they are an excellent clinical phenotype that should be the optimal therapeutic target in our practice.

Several studies have investigated the clinical characteristics of SF patients (3, 4, 5, 6). These studies have found that SF has a prevalence of 10% to 20%, and that patients are typically young, non-obese, have an active daily life, a better hepatic function, and no history of hospitalization. However, to date, no studies have comprehensively clarified the clinical characteristics of SF, including the hemodynamics and multi-end-organ function. Furthermore, there is no data on the significance of pre-Fontan hemodynamics and past history of daily physical activity during childhood (7) in predicting adult SF outcomes.

Accordingly, the aim of our study was to clarify the following clinical characteristics of SF in terms of the cross-sectional and longitudinal aspects: 1) prevalence of SF, 2) associations of current SF status with current hemodynamics and pre-Fontan hemodynamics, current multi-end-organ function, trajectory of exercise capacity (7), and daily physical activity during childhood determined in our previous study (8). Our findings could provide detailed clinical profiles of SF and useful information for establishing a better management strategy for these patients.