Abstract 13502: Impact of Udenafil on Echocardiographic Indices of Single Ventricle Size and Function in Fuel Study Participants

Abstract

Introduction: The Pediatric Heart Network’s Fontan Udenafil Exercise Longitudinal (FUEL) Trial (Mezzion Pharma Co. Ltd., NCT 02741115) demonstrated improvements in exercise capacity following 6 months of treatment with udenafil (87.5 mg po BID). The effect of udenafil on echocardiographic measures of single ventricle (SV) function in this cohort has not been studied. Methods: Protocol echocardiograms were obtained at baseline and 26 weeks after initiation of udenafil/placebo. Linear regression compared change from baseline in indices of SV systolic, diastolic and global function, atrioventricular valve (AVV) regurgitation and mean Fontan fenestration gradient in the udenafil cohort vs placebo, controlling for ventricular morphology (LV vs. RV/other). Effects of ventricular morphology on echo measures and its interaction over time was also evaluated. Difficult imaging windows limited consistent capture of all measures. Results: The 191 udenafil participants had significantly improved myocardial performance index (p=0.03), AVV inflow peak E and A velocities (p = 0.007 and 0.03), and annular DTI-derived peak e’ velocity (p = 0.008) compared to 195 placebo participants (Table). There were no significant differences in change in SV size, systolic function, AVV regurgitation severity or mean fenestration gradient. Although LV morphology participants had significantly more favorable indices of SV size and function (lower volumes and areas, E/e’ ratio, systolic:diastolic time and AVV regurgitation, and higher annular s’ and e’ velocity) at baseline, there was no differential effect of udenafil by ventricular morphology at 26 weeks. Conclusions: FUEL participants who received udenafil demonstrated a significant improvement in global and diastolic echo indices. The changes in diastolic function suggest improvement in pulmonary venous return and/or augmented ventricular relaxation, which may help explain improved exercise performance in that cohort.