Abstract Body: Background: Patients with Fontan palliation have reduced aerobic capacity because of impaired cardiac, pulmonary, and skeletal muscle function. However, the assessment of aerobic capacity in this population still relies on comparisons with people without cardiovascular disease, rather than comparison with the expected aerobic capacity of other Fontan patients. The purpose of this study was to determine the expected aerobic capacity of adults with Fontan palliation.
Method: Adults with Fontan palliation who underwent cardiopulmonary exercise test at Mayo Clinic (2003-2023) were stratified into quartiles based on the predicted peak VO₂. We assessed the correlates of predicted peak VO₂, and the relationship between predicted peak VO₂ quartiles and cardiovascular outcomes (death/transplant).
Results: Of 323 patients (age 29±9 years; 177 [55%] men), the median peak VO2 was 19.1 (15.2 - 23.9) ml/kg/min, and this corresponds to a predicted peak VO₂ of 51% (range 19 -88; interquartile range 41 - 62). The correlates of higher predicted peak VO₂ were smaller body mass index, higher systemic saturation, and lower Fontan pressures. The top, 2^nd,3^rd, and bottom quartile of predicted peak VO₂ corresponds to predicted peak VO₂ of 63-88%, 51-62%, 41-50%, and 19-40%, respectively. Using the top quartile as the reference, the 3^rd quartile (HR 1.13, 95% CI 1.03-1.28, p=0.02), and 4^th quartile were associated with a higher risk of death/transplant (HR 1.32, 95% CI 1.16-1.69, p<0.001).
Conclusions: The results of the current study would help calibrate the interpretation of exercise test data in adults with Fontan palliation and improve risk stratification in this population.