Abstract 11959: Cardiopulmonary Exercise Testing Delineates Multiple Contributing Factors to Poor Exercise Performance in Childhood Cancer Survivors

Abstract

Background: Childhood cancer survivors (CCS) show decreased exercise performance despite normal ventricular function at rest. Multiple underlying mechanisms are considered. Methods: Cardiopulmonary exercise testing (CPET) was performed in asymptomatic off-treatment CCS. Patients were divided into four groups by their peak oxygen consumption (pVO2) at 35 and 25 ml/kg/min in males and females, respectively (“Good” and “Poor” performance groups). * denotes weight-indexed values. Data are shown as mean ± standard deviation. Results: Demographic and CPET data are presented in Table 1. There was no notable correlation between total anthracycline dosage and CPET values. Weight, body mass index, and peak respiratory exchange ratio were significantly higher in “Poor” groups in both sexes. Peak oxygen pulse (pOP*) and ventilatory anaerobic threshold (VAT*) were significantly lower whereas heart rate (HR) dependency on work rate (WR*) (= ΔHR/ΔWR*) was significantly higher in “Poor” groups than in “Good” groups. There was no difference in ventilatory efficiency presented as a slope of ventilation (VE)/carbon dioxide output (VCO2)(ΔVE/ΔVCO2). Figure 1 demonstrated the relationship between weight and pVO2 (L/min) and between ΔHR/ΔWR* and pOP*, showing distinct difference between “Good” and “Poor” performers in both sexes; “Poor” performers revealed lower skeletal mass and stroke volume effects. Conclusions: Treatment-mediated cardiotoxicity is not the only cause of poor exercise performance in CCS. In addition to limited stroke volume indicated by lower pOP* with higher HR dependency, skeletal muscle loss and increased BMI mitigated the overall exercise performance.