Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term study.

We have recently reported that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension in a 24-week prospective study and well tolerated without adverse events. We now aimed to evaluate clinical efficacy, safety of switch in a larger patient population, in a 24-month prospective study.

This is a single-institution, 24-month prospective study. Patients ≥12 years with idiopathic/heritable, pulmonary arterial hypertension, or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan treatment were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors/inhaled prostanoids was allowed. Outcome measures included change from baseline to 24 months, in the 6-minute walk distance, functional class, oxygen saturation at rest/after walk distance test, and natriuretic peptide levels. Safety end points included adverse events, laboratory abnormalities.

Twenty-seven patients (19 adults/8 children, mean age: 21.1 ± 6.3 years (12–36), weight: 53.1 ± 15.7 kgs (26–87)) were included. Mean duration of macitentan treatment: 22.3 ± 3.9 months (9–24). Six-minute walk distance significantly improved from baseline (mean: 458 ± 79 m (300–620)) at 6 months (mean: 501 ± 73 m (325–616) + 43 m) (p < 0.05), at 12 months (mean: 514 ± 82 m (330–626) + 56 m) (p < 0.05), and at 24 months (mean: 532 ± 85 m (330–682) + 74 m) (p < 0.05). We observed a significant improvement during the first 6 months but no incremental improvement after 6 months (p > 0.05). Macitentan did not significantly change functional class, oxygen saturation, and natriuretic levels (p > 0.05). None of the patients had anaemia, hepatotoxicity, and peripheral edema.

Our study is the first study which showed that switch from bosentan to macitentan improved exercise capacity in children and young adults with pulmonary arterial hypertension significantly in the first 6 months and compared to baseline in 24 months and well tolerated without adverse events.

Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term event-driven study.

Few studies compared the clinical efficacy and safety of switch from bosentan to macitentan only in adult patients with pulmonary arterial hypertension. We aimed to evaluate the clinical efficacy and safety of switch from bosentan to macitentan in children and young adults.

This is a single-institution, 24-week prospective study. Patients ⩾12 years of age with idiopathic/heritable pulmonary arterial hypertension or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan therapy were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors and inhaled prostanoids was allowed. Outcome measures included change from baseline to week 24, in the 6-minute walk distance, functional class, oxygen saturation at rest/after 6-minute walk distance test, systolic pulmonary artery pressure estimated by echocardiography, and brain natriuretic peptide levels. Safety end points included adverse events laboratory abnormalities.

A total of 13 patients – 5 male and 8 female – completed the study. The mean age was 20.3±6.5 years (12–35) and weight was 54.0±14.5 kg (27–75). Five patients were ⩽18 years of age. Macitentan improved 6-minute walk distance from baseline (mean: 466±35 m (300–590)), at 12 weeks (mean: 494±78 m (325–590), +28 m) (p<0.05), and at 24 weeks (mean: 507±58 m (325–625), +41 m) (p<0.05). Macitentan did not significantly change functional class, oxygen saturation at rest/after 6-minute walk distance test, brain natriuretic levels, and systolic pulmonary artery pressure (p>0.05). None of the patients had anaemia, hepatotoxicity, and peripheral oedema.

Our study is the first study that showed that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension and is well tolerated without any adverse events.