S93 REPAIR: long-term effects of macitentan on the right ventricle (RV) in pulmonary arterial hypertension (PAH)

Introduction and Objectives In a study of patients with PAH (REPAIR), macitentan improved RV stroke volume (RVSV) and measures of RV function at Week 26. This study aimed to assess whether the effects of macitentan at Week 26 were maintained at Week 52. Methods REPAIR (NCT02310672) was a 52-week, multicentre, open-label, single-arm phase 4 study. Macitentan 10 mg was initiated in treatment-naive PAH patients, in patients receiving stable background phosphodiesterase type-5 inhibitor (PDE5i) at baseline (BL), or in initial combination with PDE5i. RV cardiac magnetic resonance imaging (cMRI) variables, 6-minute walk distance (6MWD) and WHO functional class (FC) were assessed at Weeks 26 and 52. Results Analyses included 71 patients (80% female; BL: median age 45 years, median 6MWD 395 [Q1, Q3: 323, 483] m, 98.6% FC II/III). At Weeks 26 and 52, mean (95% CL) change from BL in 6MWD was 36 (19, 52) and 38 (19, 57) m; FC improved in 40/70 (56%) and 34/65 (48%) patients; no patients worsened. The table 1 shows RV parameter changes at Weeks 26 and 52. Conclusions Improvements in RV mass, volume and function observed with macitentan at Week 26 were maintained at Week 52. Please refer to page A240 for declarations of interest related to this abstract.