- A PVR>1000dynes.sec.cm-5(as assess by RHC at screening or in the 2 months preceding the screening visit despite treatment with two or more specific PAH therapies, including endothelin receptor antagonists (ERA), phosphodiesterase 5 inhibitors (PDE5), or inhaled, intravenous or oral prostacyclin analogues for ≥3 months. On stable background therapy doses for ≥ 30 days except for warfarin (≥30 days but doses can vary even within the mouth before enrollment)