Clinical Study to Assess the Long-term Safety, Tolerability, and Efficacy of Macitentan in Subjects With Eisenmenger Syndrome

Change in Exercise Capacity as Measured by 6-minute Walking Distance (6MWD) Month 6 and 12

NOTE: The MAESTRO-OL study was exploratory in nature and no primary efficacy and safety endpoint were defined in the clinical protocol. This and the other exploratory efficacy outcome measures posted were selected to be reported as a primary endpoints. All efficacy analyses were considered exploratory. The analyses of the exploratory efficacy endpoints focused on the absolute values and on the change from DB baseline to Week 16 in the DB study and to Month 6 and Month 12 in the OL study. For missing 6MWD values in the OL study, the following imputation rules were applied: If the reason for missing data was death, a distance of zero (0) meters was imputed for all 6MWD visits from the date of death. For any other reasons, the last available value was carried forward.

Time frame: From baseline in DB parent study (AC-055-305, NCT01743001) up to month 12 in this OL study.

Change in WHO Functional Class (FC) at Month 6 and 12

Class I: no symptoms with exercise or at rest. No limitation of activity. Class II: No symptoms at rest but slight limitation with ordinary activities causing symptoms (e.g. short of breath with climbing stairs). Class III: may not have symptoms at rest but activities greatly limited by shortness of breath, fatigue, or near fainting. Class IV: symptoms at rest and inability to carry out any physical activity without symptoms. Patients in class IV manifest signs of right heart failure. For missing WHO FC values in the OL study, the following imputation rules were applied: If the reason for missing data was death, class IV was imputed for all WHO visits from the date of death. For any other reasons, the last available value was carried forward.

Time frame: From baseline in DB parent study (AC-055-305, NCT01743001) up to month 12 in this OL study.

Change in Borg Dyspnea Score at Month 6 and 12

The Borg dyspnea score rates the severity of dyspnea (difficult or labored breathing) on a scale from 0 ('Nothing at all') to 10 ('Very, very severe - maximal'). For missing Borg dyspnea index values in the OL study, the following imputation rules were applied: If the reason for missing data was death, a value of 10 was imputed for all Borg visits from the date of death. For any other reasons, the last available value was carried forward.