Trial to Evaluate Parenteral Treprostinil and Riociguat on Right Ventriculo-vascular Coupling and Morphology in Those With Advanced PAH

The purpose of this study is to evaluate the combined effect of parenteral treprostinil (TRE) and riociguat (RIO) versus parenteral TRE alone on right ventricular (RV)-pulmonary artery (PA) interaction (RVPA coupling) and global RV function in patients with advanced pulmonary arterial hypertension (PAH).