Exercise Capacity and Predictors of Performance After Fontan: Results from the Pediatric Heart Network Fontan 3 Study

Impaired exercise following Fontan is a surrogate of morbidity. Single-center longitudinal data exist, but there is a lack of contemporary multi-center data. Ramp cycle ergometry was re-performed in consented participants who had originally participated in the Pediatric Heart Network's Fontan cross-sectional study. Annualized change was evaluated at maximal and submaximal exercise. Associations between these outcomes and patient characteristics were analyzed. There were 336 participants in Fontan 3, mean age 23.2 years. Paired measurements of peak oxygen consumption (peak VO₂) were available for 95; peak exercise data at Fontan 3 were available for 275. Percent-predicted peak VO₂ declined by 0.8 ± 1.7% per year (p < 0.001). At Fontan 3, the lowest performing peak VO₂ tertile had the highest rate of overweight and obesity (p < 0.001). Female gender was more prevalent in the highest performing tertile (p = 0.004). Paired data at the ventilatory anaerobic threshold (VO₂ at VAT) were available for 196; VAT data at Fontan 3 were available for 311. Percent-predicted VO₂ at VAT decreased by 0.8 ± 2.6% per year (p < 0.001). At Fontan 3, VO₂ at VAT was better preserved than peak VO₂ across all tertiles, with higher rates of overweight and obesity in the lower performing group (p = 0.001). Female gender (p < 0.001) and left ventricular morphology (p = 0.03) were associated with better performance. Submaximal exercise is better preserved than maximal in the Fontan population, but declined at the same rate over the study period. The overall longitudinal rate of decline in exercise performance is slower than what has been described previously.