The purpose of the 24-week, randomized, double blind, placebo-controlled study is to learn how the study medicine called PF-07868489 is tolerated and acts in healthy adult people and people with pulmonary arterial hypertension (PAH). Key Inclusion Criteria: diagnosis of pulmonary arterial hypertension (PAH), stable dose of standard of care PAH vasodilators, BMI 16 to 32 kg/m2; and a total body weight >45 kg, 6MWD ≥ 150 and ≤ 450, Pre-randomization RHC documenting a minimum of PVR ≥ 400 dyn ∙sec/cm5.
