Wadey CA; Children’s Health & Exercise Research Centre (CHERC) University of Exeter, Exeter, UK & hospitals in Australia
Barker AR; Stuart AG; Dorobantu DM; Pieles GE; Tran DL; Laohachai K; Ayer J; Weintraub RG; Cordina R; Williams CA;
Journal of the American Heart Association [J Am Heart Assoc] 2024 Dec 17; Vol. 13 (24), pp. e034944.
Date of Electronic Publication: 2024 Dec 14.
Background: Peak oxygen consumption (peak VO 2 ) is traditionally scaled by body mass, but it is most appropriately scaled by fat-free mass. However, it is unknown whether peak VO 2 scaled by fat-free mass is associated with mortality and morbidity in people with a Fontan circulation. The aim of this study was to assess the associations between different expressions of peak VO 2 with mortality and morbidity in people with a Fontan circulation.
Methods and Results: Eighty-seven participants (aged 24.1±7.3 years; 53% women) with a Fontan circulation completed a cardiopulmonary exercise test and a dual-energy x-ray absorptiometry scan. Cox proportional hazard regressions models assessed the association (hazard ratio [HR]) between different expressions of peak VO 2 with a composite outcome of Fontan failure (FF). Participants were followed up for a median of 6.5 years (95% CI, 6.4-6.9). Individuals experiencing FF (n=10/87) had a significantly lower absolute peak VO 2 . In univariable models, peak VO 2 ratio scaled to body mass was not significantly associated with FF (HR, 0.91; P =0.111). However, peak VO 2 scaled by fat-free mass (HR, 0.90; P =0.020) or lean mass (HR, 0.90; P =0.017) was significantly and inversely associated with FF. These associations remained significant after adjusting for age, sex, and peak respiratory exchange ratio.
Conclusions: The association between peak VO 2 and FF is improved when scaled to measures of body composition. Applied clinically, a 1-unit increase in peak VO 2 scaled to fat-free mass or lean mass is associated with a ≈10% lower risk of FF.