A Study of Macitentan in Japanese Pediatric Participants With Pulmonary Arterial Hypertension

Inclusion Criteria: * Pulmonary arterial hypertension (PAH) belonging to the nice 2013 updated classification group 1 * PAH diagnosis confirmed by historical right heart catheterization where in the absence of pulmonary vein obstruction and/or significant lung disease pulmonary artery wedge pressure (PAWP) can be replaced by left atrium pressure (LAP) or left ventricular end diastolic pressure (LVEDP) (in absence of mitral stenosis) assessed by heart catheterization * World Health Organization (WHO) functional class (FC) I to IV * PAH-specific treatment-naïve participants or participants on PAH-specific treatment * A female of childbearing potential must have a negative highly sensitive serum beta-human chorionic gonadotropin (beta-hCG) test at screening and a negative urine pregnancy test at the first administration of study intervention * A female participant must not get pregnant and must agree not to donate eggs during the study and for a period of up to 4 weeks following the end of study Exclusion Criteria: * Participants with PAH due to portal hypertension, schistosomiasis, pulmonary veno-occlusive disease, and/or pulmonary capillary hemangiomatosis, and persistent pulmonary hypertension of the newborn * Participants with the following diseases: pulmonary vein stenosis; bronchopulmonary dysplasia * Severe hepatic impairment, example, Child-Pugh Class C, at screening * Pregnant, or breast-feeding, or planning to become pregnant while enrolled in this study or within 4…