Abstract 16024: Effect of Tadalafil on Exercise Parameters in Young Fontan Patients
Aim: Sildenafil improves ventilatory efficiency during exercise in Fontan patients, but requires three times a day dosing. We sought to assess the effects of a long-acting phosphodiesterase-5 inhibitor (single daily dosing with tadalafil) on exercise parameters in young Fontan patients.
Methods: This was a prospective double blind, placebo-controlled, crossover trial. Subjects were randomized to receive placebo or tadalafil (1mg/kg/day; max 40 mg/day) for 7-10 days followed by crossover. Compliance was assessed by pill count. Each subject underwent exercise testing at baseline and at completion of each phase. A linear mixed-effects model was used to estimate the difference in the average post-phase exercise parameters between treatment vs. placebo.
Results: The 20 subjects (male =13) ranged in age from 8.5-20 (11.8±3.2) years. The mean age at Fontan was 3.7±1.2 years. The left ventricle was dominant in 12 (60%) and right ventricle in 8 (40%). Fenestrations were patent in 8 (40%). Following tadalafil, oxygen saturation increased and minute ventilation decreased at peak exercise (Table). At the anaerobic threshold, ventilatory equivalents of carbon dioxide (Ve/Vco2) decreased. Oxygen consumption was similar at peak exercise and at anaerobic threshold for both phases. There were no serious adverse events. Only 1 subject missed >1 dose (19/20; 95%).
Conclusions: Short term therapy with once daily dosing of tadalafil improved ventilatory efficiency and oxygen saturation, but exercise capacity was unchanged in young Fontan subjects, similar to published sildenafil results. Because compliance was excellent with daily dosing and the drug was well tolerated, tadalafil may be superior to sildenafil in this population. Associations between improved ventilatory efficiency and Fontan outcomes warrant further investigation.
- © 2013 by American Heart Association, Inc.