LAUSR

Introduction: Pulmonary atresia with intact ventricular septum (PAIVS) is surgically managed with biventricular repair (2V), 1.5 ventricle palliation (1.5V), or single ventricle palliation (1V). Cardiopulmonary exercise testing (CPET) has been increasingly utilized in these patients. However, prognostic ability of CPET is limited by achievement of maximal exercise effort [respiratory exchange ratio (RER) > 1.1]. Even during submaximal exercise, the VE/VCO2 can impact peak VO2. This study aims to identify CPET differences in 1V, 1.5V, and 2V PAIVS patients. Methods: A retrospective, cross-sectional study was performed, identifying PAIVS patients undergoing CPET. Contemporaneous echocardiography and CMR data was collected. CPET measures were compared by treatment group using ANOVA, Kruskal-Wallis, and chi-squared test, as appropriate. Comparisons of VE/VCO2 between individual groups were performed using Wilcoxon test. Univariate associations with VE/VCO2 were determined using Pearson correlation. Results: Nineteen PAIVS patients were identified (age 12.4 ± 0.68; seven 1V, five 1.5V, seven 2V). Only 7/19 (36.8%) patients achieved RER > 1.1. Sex, age, RER, peak VO2, ventilatory anaerobic threshold, O2 pulse, BSA-adjusted O2 pulse, peak HR, and HR reserve did not differ between treatment groups. The VE/VCO2 ratio was different (p=0.037), with lower VE/VCO2 in 1.5V vs. 1V (p=0.021). Across all PAIVS patients, univariate associations with lower VE/VCO2 were male sex, higher BSA, hematocrit, and O2 pulse, and lower mitral inflow A wave velocity. In the 1.5V and 2V patients, higher RVEF and RV stroke volume by CMR were associated with lower VE/VCO2. Conclusions: The 1.5V palliation of PAIVS may be associated with better gas exchange efficiency compared to 1V palliation, while 2V patients were not different from either 1V or 1.5V. BSA-adjusted O2 pulse did not vary between treatment pathways, suggesting similar stroke volume response across all patients.