Abstract 9439: Inhaled Iloprost Improves Exercise Function in Subjects after Fontan Palliation
Background: The exercise capacity of pts who have had Fontan surgery is often depressed. We hypothesized that an inability to reduce pulmonary vascular resistance appropriately during exercise contributes to this exercise intolerance, and that administration of an effective pulmonary vasodilator would improve exercise function after Fontan. Purpose: To determine whether treatment with iloprost, (ILO, a potent, selective, inhaled pulmonary vasodilator) improves exercise function in pts with Fontan.
Methods: Double-blind, randomized, placebo controlled, crossover trial. All pts performed 2 symptom-limited cardiopulmonary exercise tests (CPX) on different days separated by <1 month. Nebulizer treatment was administered before each test; one contained ILO (5 mcg), the other placebo.
Results: We recruited 18 Fontan pts aged 12-49 (median 18) yrs. Mild throat/chest discomfort developed in 10/18 pts during ILO administration; all but 1 were able to complete treatment. No symptoms were reported during placebo treatments (p<0.001). Two additional pts did not complete CPX: one was noted to be in recurrent atrial flutter, the other, with developmental issues, could not cooperate adequately for CPX. In the 15 subjects with analyzable CPX data, oxygen pulse (a surrogate for stroke volume) at peak exercise was significantly higher following ILO treatment (11.7±2.7 ml/beat vs. 10.4±2.1 ml/beat following placebo; p<0.001). Peak oxygen consumption (VO2) trended higher after ILO compared to placebo (28.7±6.7 vs. 27.5±5.9 ml/kg/min; p=0.18). Nine pts had a peak VO2 <30 ml/kg/min following placebo; each of these pts had a higher peak VO2 following ILO (25.5±4.7 vs. 23.7±4.4 ml/kg/min; p<0.002). In contrast, only 3/6 pts with peak VO2 >30 ml/kg/min on their placebo study had a higher peak VO2 following ILO (p<0.04).
Conclusion: ILO therapy improves peak VO2 in subjects with compromised exercise function after Fontan palliation. The improvement is related to an increase in the oxygen pulse at peak exercise. The therapy appears to be associated with minor side effects. These findings support the concept of pulmonary vasodilator therapy in Fontan pts with limited functional capacity.
- © 2012 by American Heart Association, Inc.