Study of Sotatercept in Newly Diagnosed Intermediate- and High-Risk PAH Participants (MK-7962-005/A011-13)

This is a phase 3, randomized, double-blind, placebo-controlled study to evaluate sotatercept when added to background PAH therapy in newly diagnosed intermediate- or high risk PAH participants. Participants enrolled in the study will have a diagnosis within 12 months of study screening of symptomatic PAH (World Health Organization \[WHO\] Group 1, classified as functional class \[FC\] II or III) and presentation of idiopathic or heritable PAH, PAH associated with connective tissue diseases (CTD), drug- or toxin- induced PAH, post shunt correction PAH, or PAH presenting at least 1 year following the correction of congenital heart defects. As of Amendment 11, this study will be closed so that all eligible participants can receive sotatercept either on the MK-7962-004 extension study (SOTERIA, NCT04796337) or by commercial access, if available. All eligible participants will complete the end of treatment visit before enrollment in the extension study or initiation of commercial product. Participants not enrolling into the extension study or initiating commercial product will complete the end of study visit.