Outcome Study Assessing a 75 Milligrams (mg) Dose of Macitentan in Patients With Pulmonary Arterial Hypertension

Inclusion Criteria:

• Target population: greater than or equal to (>=) 18 (or the legal age of consent inthe jurisdiction in which the study is taking place) years of age

• Target population: Symptomatic Pulmonary Arterial Hypertension (PAH) in World HealthOrganization Functional Class (WHO FC) II, III, or IV

• Target population: PAH subtype falling in one of the below classifications:Idiopathic; Heritable; Drug- or toxin-induced; Related to: Connective tissuedisease, HIV infection, Portal hypertension, and Congenital heart disease withsmall/coincidental cardiac defect with systemic-to-pulmonary shunt (for exampleatrial septal defect, ventricular septal defect, patent ductus arteriosus,atrioventricular septal defect) which does not account for the elevated pulmonaryvascular resistance (PVR) or persistent PAH documented by an Right heartcatheterization (RHC) >= 1 year after simple systemic-to pulmonary shunt repair

• PAH diagnosis confirmed by hemodynamic evaluation at rest at any time prior toscreening: Mean pulmonary artery pressure (mPAP) greater than (>) 20 millimeters ofmercury (mm Hg), and; Pulmonary artery wedge pressure (PAWP) or left ventricular enddiastolic pressure (LVEDP) less than or equal to (<=) 15 mm Hg, and PVR >= 3 WoodUnits (that is, >= 240 dyn*sec/cm^5)

• Able to perform the 6-minute walking test (6MWT) with a minimum distance of 50meters (m) and maximum distance of 440m at screening. Participants able to walk morethan 440m at screening are eligible if they are in WHO FC III or IV and n-terminalprohormone of brain natriuretic peptide or n-terminal pro B-type natriuretic peptide (NT-proBNP) level is >=300 nanograms per liter (ng/L) at screening, based on centrallaboratory results

Exclusion Criteria:

• Known presence of three or more of the following risk factors for heart failure withpreserved ejection fraction at screening, based on records that confirm documentedmedical history: Body mass index (BMI) > 30 kilograms per meter square (kg/m^2),Diabetes mellitus of any type, Essential hypertension (even if well controlled);Coronary artery disease, that is, any of the following: history of stable angina, orknown more than 50 percent (%) stenosis in a coronary artery, or history ofmyocardial infarction, or history of or planned coronary artery bypass graftingand/or coronary artery stenting

• Presence of moderate or severe obstructive lung disease (forced expiratory volume in 1 second [FEV1] / forced vital capacity [FVC] < 70%; and FEV1 < 60% of predictedafter bronchodilator administration) ) in participants with a known or suspectedhistory of significant lung disease as documented by a spirometry test performedwithin 1 year prior to screening

• Known moderate to severe hepatic impairment, defined as Child-Pugh Class B or C,based on records that confirm documented medical history

• Serum aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) > 1.5*upper limit of normal (ULN) at screening

• Hemoglobin < 100 gram per liter (g/L) (< 10 gram per deciliter [g/dL]) at screening