A retrospective review of sildenafil in the Australia and New Zealand Fontan registry: indications and treatment responses

Introduction: Rates of morbidity and mortality are high in the setting of Fontan physiology and effective medical therapies are not well-established. Clinical trials assessing phosophodiesterase-5-inhibitors, such as sildenafil, have not demonstrated major benefit in patients with a Fontan-type circulation but have only included stable, well-functioning people.

Methods: We sought to retrospectively characterize the people followed by the ANZ Fontan Registry prescribed sildenafil >30 days post Fontan-surgery.

Results: Of 1867 individuals, 19 (1 %) were prescribed sildenafil and met inclusion criteria; 12 (63 %) were female. Age at commencement was 9 years (IQR 13.5). Reasons for commencement were Fontan failure with elevated Fontan pressure (n = 4), failure without elevated pressure (n = 4), elevated pressure without failure (n = 6), failure symptoms without invasive assessment (n = 3) and pulmonary arterio-venous malformations (n = 2). At baseline hemodynamic study (n = 16) median Fontan pressure was 15.5 mmHg (IQR 3.1) and PVRi was 2.3 WU*m² (IQR 1.6). Improvement in the clinical indication was noted in 11/19 (58 %). In the subset in whom sildenafil was commenced with PVRi >2 WU*m² 6/7 (86 %) improved clinically. PVRi decreased by 1.8 WU*m² (IQR 1.0, n = 5, p = 0.03) on treatment in this group, compared with the <2 WU*m² group which increased by 0.3 WU*m² (IQR 0.2, n = 3, p = 0.01).

Conclusions: Some individuals with a Fontan circulation may benefit from sildenafil. Adequately designed clinical trials are needed.