Inclusion Criteria:  Participant must sign an informed consent form (ICF) (or their legally acceptable representative must sign) indicating that participant understands the purpose of, and procedures required for, the study and is willing to participate in the study Participant treated with macitentan 10 milligrams (mg) or selexipag or fixed dose combination (FDC) of macitentan 10 mg and tadalafil 40 mg at the end of a sponsor parent study and: a) the indication of the parent study is included in the protocol (PLATYPUS); b) participant has completed the parent study; c) no alternative means of access to study intervention have been identified; d) participant may continue to benefit from treatment with the study intervention A woman of childbearing potential must: a) have a negative urine or serum pregnancy test prior to first intake of study intervention; b) agree to perform monthly urine pregnancy test up to the end of the safety follow-up period; c) agree to follow contraceptive methods until 30 days after the last intake of the study intervention  Exclusion Criteria:  General:  Participants prematurely discontinued from their parent study Female participant being pregnant, or breastfeeding, or planning to become pregnant while enrolled in this study Planned or current treatment with another investigational treatment  Macitentan-specific:  Known allergies, hypersensitivity, or intolerance to macitentan or its excipients Serum aspartate (AST) and/or alanine aminotransferases (ALT) greater than (>) 3* upper limit of normal (ULN) range Known and documented severe hepatic impairment that is, Child-Pugh Class C. For participants with hepatic impairment, Child-Pugh Class (Child-Pugh score) should be fully assessed and documented in the source documents at screening  Selexipag-specific:  Known allergies, hypersensitivity, or intolerance to selexipag or its excipients Suspected or known pulmonary veno-occlusive disease (PVOD) Uncontrolled thyroid disease Known and documented severe hepatic impairment that is, Child-Pugh Class C. For participants with hepatic impairment, Child-Pugh Class (Child-Pugh score) should be fully assessed and documented in the source documents at screening  Macitentan/tadalafil FDC-specific:  Known allergies, hypersensitivity, or intolerance to macitentan or tadalafil or their excipients Known and documented severe hepatic impairment that is, Child-Pugh Class C. For participants with hepatic impairment, Child-Pugh Class should be fully assessed and documented in the source documents at screening