Clinical and invasively-measured predictors of high exercise capacity in Fontan patients

Abstract

Introduction: Fontan patients have variable exercise capacity. Contemporary understanding as to which factors predict high tolerance is limited.

Methods: Records from the Ahmanson/University of California, Los Angeles Adult Congenital Heart Disease Center were reviewed for adult Fontan patients who underwent CPET. Patients were considered "high performers" if their maximum oxygen uptake (VO₂ max/kg)-predicted was greater than 80%. Cross-sectional clinical, hemodynamic, and liver biopsy data was gathered. High-performers were compared to control patients across these parameters via associations and regression.

Results: A total of 195 adult patients were included; 27 patients were considered "high performers". They had lower body mass indices (BMI, p < 0.001), mean Fontan pressures (p = 0.026), and cardiac outputs (p = 0.013). High performers also had higher activity levels (p < 0.001), serum albumin levels (p = 0.003), non-invasive and invasive systemic arterial oxygen saturations (p < 0.001 and p = 0.004), lower New York Heart Association (NYHA) heart failure class (p = 0.002), and were younger at Fontan completion (p = 0.011). High performers had less severe liver fibrosis (p = 0.015). Simple regression found Fontan pressure, non-invasive O₂ saturation, albumin level, activity level, age at Fontan surgery, NYHA class, and BMI to predict significant changes in VO₂ max/kg %-predicted. These associations persisted in multiple regression for non-invasive O₂ saturation, NYHA class II, activity level, and BMI.

Conclusions: Thin Fontan patients who exercise more had better exercise capacity, Fontan hemodynamic profiles, and less liver fibrosis.

Keywords: BMI; CPET; Exercise; Fontan; Outcomes.