Investigation of the Effects of Switching from Bosentan to Macitentan in Pediatric Pulmonary Hypertension Patients.

Objectives: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by increased pulmonary vascular resistance and reduced exercise capacity. Bosentan, an endothelin receptor antagonist, is commonly used in pediatric PAH, but standardized guidelines for its use are lacking. Macitentan, another endothelin receptor antagonist, offers advantages such as a longer duration of action, greater tissue penetration, and lower hepatotoxicity. Methods: This retrospective study evaluated 21 pediatric patients (≥12 years) who transitioned from bosentan to macitentan due to worsening functional class and increased pulmonary artery pressure. Patients received 10 mg of macitentan daily after obtaining regulatory approval. Clinical assessments, including WHO functional class, NT-proBNP levels, transthoracic echocardiographic systolic pulmonary artery pressure (sPAP), and six-minute walk test (6MWT) distances, were conducted before and 6 months after the switch. Results: At follow-up, the prevalence of WHO functional class III decreased from 66% to 19% (p=0.001). Median NT-proBNP levels significantly decreased from 1361.01 pg/mL to 906.06 pg/mL (p=0.009). Median sPAP also showed a statistically significant reduction (p=0.001). Additionally, 6MWT distances improved significantly (p=0.002). No adverse events, hospitalizations, or significant changes in liver function tests were observed. Conclusion: Macitentan demonstrated favorable efficacy and safety in pediatric patients with PAH, particularly those with idiopathic PAH. Its once-daily regimen may improve adherence and clinical outcomes. These findings are consistent with adult studies and highlight macitentan as a promising treatment option for pediatric PAH. Larger-scale studies are needed to establish its role in clinical guidelines.