A Long Term Study to Find Out if Macitentan is an Effective and Safe Treatment for Patients With Heart Failure With Preserved Ejection Fraction and Pulmonary Vascular Disease

Inclusion Criteria:

Signed and dated Informed Consent Form (ICF).
Participant remained in the main study (SERENADE/AC-055G202, NCT03153111) for: a) 52 weeks after randomization if entered this Open-label (OL) extension study prior to protocol Version 4, b) At least 24 weeks after randomization if entering this OL extension study under protocol Version 4
A woman of childbearing potential is eligible only if: (1) Negative pre-treatment serum pregnancy test; (2) Agreement to undertake monthly pregnancy tests from the enrollment visit up to at least 30 days after study treatment discontinuation; and (2) Agreement to use reliable contraception from at least 30 days prior to the enrollment visit up to at least 30 days after study treatment discontinuation.

Exclusion Criteria:

Premature discontinuation of study treatment in the main study (SERENADE/AC-055G202, NCT03153111) due to an adverse event related to: (1) Edema or fluid retention; (2) Worsening of heart failure; (3) Liver aminotransferase elevation; and (4) Study treatment, based on investigators' discretion
Liver aminotransferase elevations, at the enrollment visit, fulfilling the following criteria: (1) Alanine amino transferase (ALT) / aspartate aminotransferase (AST) greater than or equal to (>=) 8 * the upper limit of normal (ULN); (2) ALT/AST >= 3 * ULN and associated clinical symptoms of liver injury, for example: nausea, vomiting, fever, abdominal pain, jaundice, unusual lethargy or fatigue, flu-like syndrome (arthralgia, myalgia, fever); and (3) ALT/AST >= 3 * ULN and associated increase in total bilirubin to >= 2 * ULN
Treatment with the following forbidden medications within 1 month prior to the enrollment visit: (1) Treatments that may interfere with the assessment of efficacy (that is, endothelin receptor antagonists, prostanoids, phosphodiesterase-5 inhibitors, guanylate cyclase stimulators); (2) Strong cytochrome P-450 3A4 (CYP3A4) inducers such as rifabutin, rifampin, rifampicin, rifapentin, carbamazepine, phenobarbital, phenytoin, or St. John's wort; (3) Strong CYP3A4 inhibitors such as ketoconazole, itraconazole, voriconazole, clarithromycin, telithromycin, nefazodone, ritonavir, and saquinavir or a moderate dual CYP3A4/CYP2C9 inhibitor (for example, fluconazole or amiodarone) or co-administration of a combination of moderate CYP3A4 (for example, ciprofloxacin, cyclosporine, diltiazem, erythromycin, verapamil) and moderate CYP2C9 inhibitors (for example, miconazole, piperine), in the 1-month period prior to baseline. This will not necessarily apply to participants who are already well-managed on such an ongoing combination; and (4) any other investigational treatment
Pregnant, planning to be become pregnant or lactating.
Any known factor or disease that might interfere with treatment compliance, study conduct, or interpretation of the results, such as drug or alcohol dependence or psychiatric disease.
Known hypersensitivity to macitentan or drugs of the same class, or any of the study drug excipients (for example, soy lecithin, lactose)