Peak Oxygen Consumption Scaled to Body Composition Is Associated With Mortality and Morbidity in People With a Fontan Circulation.

Abstract

Listen

Translate article

Peak oxygen consumption (peak O2) is traditionally scaled by body mass, but it is most appropriately scaled by fat-free mass. However, it is unknown whether peak O2 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 O2 with mortality and morbidity in people with a Fontan circulation. 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 O2 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 O2. In univariable models, peak O2 ratio scaled to body mass was not significantly associated with FF (HR, 0.91; P=0.111). However, peak O2 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. The association between peak O2 and FF is improved when scaled to measures of body composition. Applied clinically, a 1-unit increase in peak O2 scaled to fat-free mass or lean mass is associated with a ≈10% lower risk of FF.