Age at Fontan procedure impacts exercise performance in adolescents: results from Pediatric Health Network multicenter study.

Abstract

Background: Fontan procedure is the palliative method of choice for patients with single ventricle physiology and involves separating the systemic and pulmonary circulations and placing them in series without the interposition of a normal ventricle. Optimal timing of the Fontan completion, particularly after an intermediate staging surgery, is controversial. The long-term impact of timing of Fontan completion on the exercise performance in adolescents is unknown. Methods: We used The NIH/NHLBI Pediatric Heart Network Fontan Cross-Sectional Study dataset consisting of children and adolescents age 6-18 years recruited into the study in 2003-04 for analysis. Associations between demographic, disease- and procedure-related variables, including age at Fontan procedure, and risk of inadequate effort on exercise testing were evaluated using unconditional logistic regression. Multivariate linear regression techniques were used to evaluate association of age at Fontan procedure with percent predicted V02 maximum, percent predicted O2 maximum pulse, and heart rate reserve in patients who achieved adequate exercise effort in hierarchically adjusted models. Results: Retrospective data on 405 patients who had undergone only one Fontan operation and ramp cycle ergometry were analyzed. Mean age at Fontan surgery procedure was 3.4±2 years and mean age at the time of ramp cycle ergometry was 12.4±3.2 years; 58.5% were males and 78.8% were Caucasian. 312 patients reached ventilatory anerobic threshold (VAT) suggesting adequate effort. Although the age at Fontan procedure was not related to risk of reaching VAT (p=0.97) in the fully adjusted model, age age at first unloading surgery was associated with higher risk of an inadequate effort on exercise testing (OR 1.3, 95% CI 1.06-1.60). In patients who reached the VAT, each year increase in age at Fontan completion was associated with a decline of 1.5 (95% CI -2.5 to -0.5) points in percent predicted VO2 maximum after adjusting for demographic, disease related and surgical characteristics (p=0.003). Similarly, each year increase in age at Fontan completion was associated with a decline of 4.1 (95% CI -6.0 to -2.1) beats/min in heart rate reserve (p < 0.001). Conclusions: Patients who undergo Fontan completion at an earlier age have better exercise performance than those who receive delayed surgery.