Improved low-risk criteria scores for combination therapy of sildenafil and generic bosentan in patients with congenital heart disease with severe pulmonary hypertension: A prospective open label study.

Objective: We evaluated the efficacy and safety of the bosentan as a sequential add-on therapy with sildenafil in pulmonary arterial hypertension with congenital heart disease (PAH-CHD) patients.

Material and method: Twenty patients who were receiving sildenafil were given generic bosentan for up to a year. Hemodynamic data was collected from cardiac catheterization at pretreatment and at three months. Comparisons were made between the total scores of the four, low-risk criteria adapted from the 2015 ESC/ERS pulmonary hypertension guidelines, which are: 1) WHO functional class of I or II, 2) 6MWD of more than 440 m, 3) right atrial pressure of less than 8 mm Hg, and 4) cardiac index ≥2.5 L/min/m², performed at the beginning of therapy, 3-months, 6-months, and 1 year.

Results: Patients' average age was 27 ± 11 years old (12-53). PVRi decreased from 16.7 ± 9.5 to 12.7 ± 10.3 Wood unit (WU) m2 (p = 0.025) and PVRi/SVRi decreased from 0.69 ± 0.33 to 0.49 ± 0.32 (p = 0.001). During the follow-up, the composite scoring of the low risk scores for 19 patients was increased significantly from 1.8 ± 1.0 at baseline to 2.3 ± 0.9 at 3 months, to 2.9 ± 0.8 at 6 months, and 3 ± 0.7 at 1 year (p = 0.001).

Conclusion: We demonstrated intermediate term benefits for generic bosentan as an add-on therapy to sildenafil in patients with PAH-CHD by improving PVRi, and PVRi/SVRi at three months. A significant improvement was also seen in the combined scores of the low-risk criteria from below 2 to 3 at one year (p = 0.001).Thai Clinical Trials Registry (TCTR): TCTR identification number is TCTR20200506006.