['chronic thromboembolic pulmonary hypertension']
['macitentan', 'placebo']

        Inclusion Criteria:

          -  Written informed consent

          -  Subject with CTEPH (WHO Group 4) judged as inoperable due to the localization of the
             obstruction being surgically inaccessible (i.e., distal disease).

          -  Female of childbearing potential must have a negative pre-treatment serum pregnancy
             test, be advised on appropriate methods of contraception, and agree to use 2 reliable
             methods of contraception.

        Exclusion Criteria:

          -  Previous pulmonary endarterectomy.

          -  Recurrent thromboembolism despite sufficient oral anticoagulants.

          -  Symptomatic acute pulmonary embolism in the 6-month period prior to randomization.

          -  Known moderate-to-severe restrictive lung disease (i.e., TLC < 60% of predicted value)
             or obstructive lung disease (i.e., FEV1 < 70% of predicted, with FEV1/FVC < 65%) or
             known significant chronic lung disease diagnosed by chest imaging (e.g., interstitial
             lung disease, emphysema).

          -  Acute or chronic conditions (other than dyspnea) that limit the ability to comply with
             study requirements in the 3-month period prior to Screening visit or during the
             Screening period.
      