Comparison of the oxygen uptake efficiency slope and 6-minute walk test in paediatric and adult Fontan patients
Acta Cardiologica, vol.81, no.4, pp.599-609, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 81 Issue: 4
- Publication Date: 2026
- Doi Number: 10.1080/00015385.2026.2681257
- Journal Name: Acta Cardiologica
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, EMBASE, MEDLINE, Biomedical Reference Collection: Corporate Edition (EBSCO)
- Page Numbers: pp.599-609
- Keywords: 6-minute walk test, cardiopulmonary exercise test, Fontan, Oxygen uptake efficiency slope, submaximal exercise capacity
- Hacettepe University Affiliated: Yes
Abstract
Background: Fontan patients experience progressive declines in exercise capacity, highlighting the importance of submaximal exercise parameters for clinical evaluation. Objectives: To evaluate the oxygen uptake efficiency slope (OUES/kg) compared to 6-minute walk test (6MWT) distance in paediatric and adult Fontan patients. Methods: Participants included paediatric (<18 years) and adult (≥18 years) Fontan patients and matched controls. All participants completed a treadmill CPET, and VO2peak, OUES, and related variables were recorded. 6MWT was also performed, with distance (m) recorded. Results: Thirty-one Fontan patients and 30 age- and sex-matched controls were included (paediatric: 15 vs 14, both median 12 years; adults: 16 vs 16, median 20.5 vs 20 years). Both paediatric and adult Fontan patients had significantly lower OUES/kg compared to controls (p < 0.05). 6MWT distances were significantly lower in adult patients (p < 0.05) but not in paediatric patients (p > 0.05). OUES/kg and 6MWT distance were significantly correlated with VO2peak in both groups, showing stronger correlations in adults (r = 0.884, r = 0.789, p < 0.001) than in paediatric patients (r = 0.622, r = 0.609, p < 0.05). OUES/kg discriminated between patients and controls in both age groups (AUCs = 0.724 and 0.848), while 6MWT distance did so only for adults (AUC = 0.809). Conclusion: Both OUES/kg and 6MWT distance may serve as valuable indicators of submaximal exercise capacity in Fontan patients, particularly in adults when maximal CPET is not feasible. While OUES/kg demonstrated superior discriminatory ability, the 6MWT remains a simple and clinically useful tool, especially for evaluating functional capacity in adult Fontan patients. These findings emphasise the complementary value of both measures and highlight the importance of age-specific assessments in this population.