Background: 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.Aim: 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.Methods: 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.Results: 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.Conclusions: 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.

Introduction: Accessory pathways are commonly seen due to delamination of tricuspid valve leaflets. In addition to accessory pathways, an enlarged right atrium due to tricuspid regurgitation and incisional scars creates substrates for atrial re-entries and ectopic tachycardia. We sought to describe our experience with catheter ablation in children with Ebstein’s anomaly.Methods and results: During the study period, of 89 patients diagnosed with Ebstein’s anomaly, 26 (30.9%) of them who underwent 33 ablation procedures were included in the study. Accessory pathways were observed in the majority of procedures (n = 27), whereas atrial flutter was observed in five, atrioventricular nodal reentrant tachycardia in five, and atrial tachycardia in two procedures. Accessory pathways were commonly localised in the right posteroseptal (n = 10 patients), right posterolateral (n = 14 patients), septal (n = two patients), and left posteroseptal (n = one patient) areas. Multiple accessory pathways and coexistent arrhythmia were observed in six procedures. All ablation attempts related to the accessory pathways were successful, but recurrence was observed in five (19%) of the ablations. Ablation for atrial flutter was performed in five patients; two of them were ablated successfully. One of the atrial tachycardia cases was ablated successfully.Conclusions: Ablation in patients with Ebstein’s anomaly is challenging, and due to nature of the disease, it is not a rare occasion in this group of patients. Ablation of accessory pathways has high success, but also relatively high recurrence rates, whereas ablation of atrial arrhythmias has lower success rates, especially in operated patients.