Prevalence and clinical correlates and characteristics of “Super Fontan”.
Ohuchi H, Mori A, Kurosaki K, Shiraishi I, Nakai M.Am Heart J. 2023 Sep;263:93-103. doi: 10.1016/j.ahj.2023.05.010. Epub 2023 May 20.PMID: 37211285
Commentary from Dr. Anna Tsirka (Hartford, CT, USA), section editor of Pediatric and Fetal Cardiology Journal Watch
Summary:
Super Fontan is more common in younger, slim males, however by the age of 30, no patients meet the criteria for SF any longer. Lower pre Fontan pulmonary vascular resistance and early Fontan completion were associated with SF. Type of Fontan, single ventricle morphology, and ventricular systolic function did not correlate with SF status. SF patients have superior pulmonary and hepatorenal function, as well as hemostatic function. SF patients also have lower risk for mortality and hospitalization for heart failure but no difference in the risk for hospitalization for arrhythmias. Higher levels of physical activity (over 2.8 hours per week) in childhood are strongly correlated with SF status.
Introduction
Patients with Fontan circulation exhibit lower exercise capacity compared to they are normal healthy peers. A subset however of patients with Fontan circulation (10-20%) have normal exercise capacity, and they are defined as being “super Fontan “ (SF).
This study aimed at evaluating the prevalence of the super Fontan and assess factors associated with it, such as hemodynamics, end-organ function, activity and trajectory of exercise capacity.
Methods
This is a retrospective chart review of 404 Fontan patients who underwent adequate exercise testing between 2005 and 2021 at a single hospital in Osaka, Japan. Patient’s were defined as super Fontan if they had pak VO2 over 80% of predicted. The initial diagnosis, body habitus, Fontan complications, and medications at the time of the exercise test were recorded. Exercise testing was performed within a week of a planned cardiac catheterization. 27% of the patients completed the daily activity questionnaire, and the trajectory of exercise capacity was determined in patients who had more than 1 exercise test with an interval of more than 2 years. Other factors evaluated were isometric strength, pulmonary function, hemodynamics, BNP, hepatorenal function and a liver ultrasound.
Results:
The patient characteristics are summarized in table 1. SF patients were male, were slimmer, had early Fontan completion. They had less incidence of Fontan complications. Ventricular morphology and type of Fontan did not make a difference.
The prevalence of SF decreased with age: 38% of less than 10 years, 32% at 10-20, 11% at 20-30 years, and 0% at over the age of 30 years.
Hemodynamic factors before Fontan that were statistically significant for the presence of SF were lower pulmonary vascular resistance, lower end-diastolic volume index, and higher saturations, although the differences were very small, therefore not clinically significant as indicated in table 4.
Hemodynamic factors at evaluation at the age of a exercise test revealed higher cardiac output, lower EDP, and higher saturations in those with SF. Interestingly, single ventricle systolic function did not correlate with presence of SF.
SF patients has had lower BNP, and better pulmonary function. SF patient has had better liver function, and better creatinine clearance. Interestingly, they also had better hemostatic function.
Exercise during childhood
Physical activity time (PAT) in childhood correlated with presence of SF. Child Fontan patients with PAT> 2.8 hours/week had 9.6 times higher chance of being an adult SF. There was no difference in strength between SF and non SF patients.
Unscheduled hospitalizations (USH) for heart failure were lower in the SF group, however there was no difference in USH for arrhythmia. SF patient has had lower mortality.
Conclusion
SF is associated with better long-term outcomes. Pre- Fontan hemodynamics are associated with incidence of SF, however very strong predictors of SF were physical activity over 2.8 hours in childhood and slim physiologic.
This study demonstrates the importance of promoting physical activity and healthy body composition among Fontan patients from childhood.
