Aims: We sought to assess the effects of sildenafil on exercise capacity and haemodynamic response to exercise in Fontan patients.
Methods and results: We prospectively studied 27 patients with Fontan circulation (age 22.8 +/- 4.9 years). All patients underwent a baseline exercise test with non-invasive measurement of cardiac index (CI) and pulmonary blood flow (PBF) index, and peak exercise oxygen uptake (VO(2)). After the baseline test, patients were randomly assigned to receive either a single 0.7 mg/kg body weight oral dose of sildenafil citrate (n = 18) or no treatment (control group, n = 9). After 1 h of rest, all patients performed a second exercise test. All patients completed the study protocol. The dose of sildenafil ranged from 25 to 50 mg. The change in peak VO(2), the primary endpoint, was greater in the sildenafil group (9.4 +/- 5.2%) than in the control group (0.3 +/- 4.1%, P < 0.05). Sildenafil increased rest and peak exercise PBF index (P < 0.01 and P < 0.05 vs. control group, respectively), as well as rest and peak exercise CI (P < 0.001 and P < 0.05 vs. control group, respectively), without altering rest or peak exercise transcutaneous arterial blood oxygen saturations (P > 0.05 vs. control group for both). No patient reported serious adverse events after sildenafil.
Conclusion: In Fontan patients, oral administration of a single dose of sildenafil improves exercise capacity and haemodynamic response to exercise.