Estimating equations for cardiopulmonary exercise testing variables in Fontan patients: derivation and validation...

Area of Science:

• Pediatric Cardiology
• Exercise Physiology
• Congenital Heart Disease

Background:

• Cardiopulmonary exercise testing (CPET) is crucial for evaluating Fontan circulation patients.
• Existing CPET predictive equations are based on healthy children, potentially limiting accuracy in Fontan populations.

Purpose of the Study:

• To develop novel CPET predictive equations specifically for individuals with Fontan circulation.
• To assess the performance and validity of these new equations compared to existing standards.

Main Methods:

• Utilized data from the Pediatric Heart Network Fontan Cross-Sectional Study.
• Developed predictive equations using a derivation cohort (80%) and validated them in a separate cohort (20%).
• Employed linear regression for equation derivation and validation, focusing on peak exercise variables and anaerobic threshold (AT) variables.

Main Results:

• Developed 8 predictive equations for commonly measured CPET variables.
• Peak CPET variable equations demonstrated good performance (e.g., peak VO2 R²=0.61).
• Anaerobic threshold (AT) equations showed lower variability explained (e.g., VO2 at AT R²=0.15), with two models performing significantly worse upon validation.

Conclusions:

• Six of the eight developed CPET predictive equations were successfully validated in the Fontan population.
• Equations for peak exercise variables were more robust and better explained outcome variations than AT-based equations.
• These novel equations offer a more accurate tool for assessing exercise capacity in Fontan circulation patients.