ERA: endothelin receptor antagonist; i.v.: intravenous; PDE-5i: phosphodiesterase type 5 inhibitor; RCT: randomized controlled trial; s.c.: subcutaneous; WHO-FC: World Health Organization functional class. aClass of recommendation. bLevel of evidence. cReference(s) supporting recommendations. dTime to clinical failure as primary endpoint in RCTs or drugs with demonstrated reduction in all-cause mortality (prospectively defined).