The Fontan procedure enables survival in individuals with univentricular physiology but is associated with progressive circulatory failure. Identifying predictors of adverse outcomes is essential to improve long-term management. This study evaluated five-year outcomes and baseline predictors of major events in a previously characterised paediatric and young adult Fontan cohort.

This retrospective longitudinal study included 51 patients (median age 18 years, interquartile range 11) who underwent comprehensive evaluation between 2018 and 2019, including echocardiography with atrial strain analysis and cardiopulmonary exercise testing. The composite outcome comprised death, heart transplantation listing, hospitalisation for heart failure, or conduit thrombosis. Univariable and multivariable logistic regression identified predictors of adverse outcomes.

During a five-year follow-up, 7 patients (14%) met the composite outcome. Those with events had lower body mass index (19.8 kg/m2 [4.1] vs 16.9 [3.6]; p = 0.007), lower atrial conduit strain (10.95% [8.95] vs 2.8 [6.2]; p = 0.011), reduced peak oxygen uptake, and higher VE/VCO2 slope. In multivariable analysis, lower body mass index (OR 0.49, 95% CI 0.26–0.93; p = 0.028) and reduced atrial conduit strain (OR 0.70, 95% CI 0.51–0.96; p = 0.026) were independently associated with adverse outcome, with excellent model discrimination (AUC = 0.95).

Both nutritional status and atrial functional parameters demonstrated a strong association with the outcome. Reduced atrial conduit strain, reflecting diastolic dysfunction, and lower body mass index, possibly reflecting myopenia or cachexia, identified higher-risk patients and potential areas for intervention. Routine assessment of atrial function and nutritional status should be integrated into clinical surveillance and risk stratification of the Fontan population.