Researchers are looking for new ways to treat people with a type of pulmonary hypertension called combined postcapillary and precapillary pulmonary hypertension (Cpc-PH). This study focuses on Cpc-PH that is caused by heart failure with preserved ejection fraction (HFpEF). Researchers want to know if the study treatment, sotatercept, can treat people with Cpc-PH caused by HFpEF. This is an extension study, which means people who took part in a certain study on sotatercept for Cpc-PH (called a parent study) may be able to join this study. In this extension study, people will take sotatercept and researchers will follow their health for a longer time. The main goal of this extension study is to learn about the long-term safety of sotatercept and if people tolerate it over a longer period of time.