Objectives Cardiopulmonary exercise test (CPET) provides accurate evaluation of physical capacity and disease severity in children with congenital heart disease (CHD). However, full participation to obtain optimal measure of VO2max may be difficult. As an alternative, the oxygen uptake efficiency slope (OUES) is a reproducible and reliable parameter measured during CPET, which does not require a maximal exercise to be interpretable. This study aimed to evaluate the OUES of a large cohort of children with CHD, in comparison with healthy controls. We also intended to identify, in this specific population, the clinical and CPET variables associated with the OUES.
Methods This cross-sectional study was carried out between November 2010 and September 2015 in two tertiary care paediatric and congenital cardiology centres.
Results 709 children were included (407 CHD and 302 healthy controls). The association of clinical characteristics with weight-normalised OUES (OUESkg) was studied using a multivariable analysis. The mean OUESkg was significantly lower in CHD than in healthy controls (38.6±8.5 and 43.9±8.5; p<0.001, respectively), especially in the most severe CHD. The OUESkg correlated with VO2max (r=0.85, p<0.001), with cut-off values for normal exercise capacity of 38.4 in boys and 31.0 in girls. The decrease of OUESkg was associated with increased age, increased Body Mass Index, number of cardiac catheter or surgical procedures, female gender and decreased forced vital capacity (Z-score).
Conclusion The OUES is significantly impaired in children with CHD and strongly correlates with VO2max. The OUES has the same clinical determinants as VO2max and therefore may be of interest in submaximal exercise.
Trial registration number NCT01202916.
- cardiopulmonary exercise test
- congenital heart disease
- oxygene uptake efficiency slope
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Contributors Study concept and design: AG, PA, SM. Drafting of the manuscript: AG, PA, DV. Critical revision of the manuscript for important intellectual content: all statistical analysis: HB, M-CP. Obtained funding: PA.
Funding Montpellier University Hospital Clinical Research Program (PHRC 8422) funded this study.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This study was conducted in compliance with the Good Clinical Practices and Declaration of Helsinki principles. The French South Mediterranean IV Ethics Committee (2009-A00423-54) gave its approval and all parents or legal guardians gave their informed consent.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.