Abstract 2610: Bosentan Induces Clinical and Hemodynamic Improvement in Candidates for Right Heart Bypass Surgery
Background: Bosentan, an oral dual endothelin (ET-A/ET-B) receptor antagonist, has been shown to be effective in patients with idiopathic pulmonary arterial hypertension (PAH) and PAH related to congenital heart disease. However, there are few reports so far on the effect of bosentan on elevated pulmonary vascular resistance (PVR) in patients with single ventricle (SV) physiology.
Objective: We examined the efficacy of combination therapy of bosentan and beraprost in patients with SV physiology who could not undergo right heart bypass surgery because of high PVR and PA pressure (PAP).
Method: Seven patients with SV physiology, 2 male and 5 female, aged 10m to 13 years (median 1 year) were enrolled. Prior surgical interventions included PA banding in 5 cases and Blalock-Taussig operation in 1 case. All patients were contra-indicated for right heart bypass surgery because of high PVR and PAP: all patients received beraprost, while 4 cases received HOT. Patients underwent clinical and hemodynamic evaluation at baseline and after 7 to 24 months of oral administration of bosentan.
Result: Although we administered initial doses of bosentan adjusting for their body weight, tachypnea and chest discomfort were identified in two cases. These symptoms disappeared with reduced dosages of bosentan. Bosentan therapy successfully reduced PAP and PVR in all cases. The average changes of PAP and PVR at baseline and after bosentan therapy in five patients were; right PA pressure (mmHg): 22.0±6.3 to 11.6±3.7 (p<0.05), left PA pressure (mmHg): 18.0±3.5 to 12.0±3.6 (p<0.05), PVRI (unit/m2): 5.5±2.4 to 1.9±0.8 (p<0.05), PVR/SVR: 0.36±0.19 to 0.06±0.02 (p<0.05). Clinical symptoms and NYHA class improved III to II in all cases. Bidirectional Glenn was performed in 5 cases, and 2 cases underwent successful Fontan operations.
Conclusion: Bosentan induces mid-term clinical and hemodynamic improvement in patients with SV physiology and elevated PVR and PAP. Combined therapy with bosentan and beraprost may widen the surgical options and improve outcome in candidates for right heart bypass surgery. Larger studies with long-term bosentan administration are needed to assess the optimal doses and the therapeutic role of bosentan in this population.