A multicenter, randomized, double-blind, placebo-controlled, 24-week, parallel-group study. Approximately 310 subjects will be enrolled and randomly allocated (1:1) to receive oral treprostinil or placebo, stratified by Baseline 6MWD. The primary objective of this study is to assess the effect of oral treprostinil compared with placebo on change in exercise capacity as measured by change in 6-Minute Walk Distance (6MWD) from Baseline to Week 24 in subjects with PH associated with HFpEF. The secondary objective of this study is to assess the effect of oral treprostinil compared with placebo on the following: Change in N-terminal pro-brain natriuretic peptide (NT-proBNP) levels from Baseline to Week 24 Time to clinical worsening where clinical worsening is defined by at least 1
of the following: oospitalization due to a cardiopulmonary indication, Outpatient administration of 1 intravenous (IV) diuretics, Decrease in 6MWD > 15% from Baseline (or too ill to walk) directly related
to disease under study, at 2 consecutive visits on different days, or Death (all causes) Change in World Health Organization (WHO) Functional Class from Baseline to Week 24.