This is a Phase 3, randomized, double-blind, placebo-controlled, multicenter, parallel-group study. The objective of this study is to evaluate the effects of sotatercept treatment (plus maximum tolerated background PAH therapy) versus placebo (plus maximum tolerated background PAH therapy) on time to first event of all-cause death, lung transplantation, or PAH worsening related hospitalization of ≥ 24 hours, in participants with WHO FC III or FC IV PAH at high risk of mortality. Maximum study duration for a given participant in this study will be up to approximately 49 months as follows:
- Screening Period (up to 4 weeks)
- DBPC Treatment Period (until event occurrence, up to approximately 46 months)
- Follow-up Period (up to 8 weeks)