A cross-sectional study of exercise performance during the first 2 decades of life after the Fontan operation

Objectives The aim of this study was to describe exercise performance during the first 2 decades of life in Fontan survivors by a cross-sectional study and to identify factors that influence exercise performance. Background Exercise performance after the Fontan procedure is reduced relative to performance in healthy subjects. Data on pre-adolescents are limited, and the patterns of exercise performance in different ages are unexplored. Methods Ramp cycle ergometry was performed with expired gas. Data were analyzed for the entire study population and for subpopulations that did and did not achieve a maximal aerobic capacity. Results Of 411 subjects tested (12.4 +/- 3.2 years of age), 166 achieved a maximal aerobic capacity. Peak oxygen consumption (VO2) was 26.3 ml/kg/min (65% of predicted for age and gender [% predicted]) for the entire population and was lower in the submaximal capacity subgroup compared with the maximal capacity subgroup (63% predicted and 67% predicted, respectively; p = 0.02). Oxygen consumption at ventilatory anaerobic threshold (VAT) was better preserved (78% predicted for the total population) than peak VO2. Higher % predicted O-2 pulse at peak exercise was associated with greater % predicted peak VO2, work rate, and VAT. Adolescence and male gender were associated with decreased % predicted peak VO2. The relationship between echocardiographic indexes of ventricular function and exercise function was surprisingly weak. Conclusions In Fontan patients, maximal aerobic capacity is reduced compared with healthy subjects, with better preservation of submaximal performance. Higher O-2 pulse is associated with better exercise performance, whereas adolescence and male gender are associated with decreased performance compared with healthy subjects.