Table 2. World Health Organization functional class (WHO FC) IV patients in randomised clinical trials of pulmonary arterial hypertension.

Investigational drug	Trial and publication year	Patients in WHO FC IV at baseline %
Epoprostenol	Barst et al. [20]; 1996	27
Iloprost#	Olschewski et al. [39]; 2002	42
Treprostinil	Simonneau et al. [40]; 2002	7
Bosentan	Channick et al. [41] (Study 351); 2001	0
	Rubin et al. [42] (BREATHE-1); 2002	8
Ambrisentan	Galiè et al. [43] (ARIES-1); 2008	7
	Galiè et al. [43] (ARIES-2); 2008	2
Sitaxentan	Barst et al. [44] (STRIDE-1); 2004	1
	Barst et al. [45] (STRIDE-2); 2006	4
Sildenafil	Galiè et al. [46] (SUPER-1); 2005	3
Tadalafil	Galiè et al. [47] (PHIRST-1); 2009	2

BREATHE: Bosentan Randomized Trial of Endothelin Antagonist Therapy; ARIES: Ambrisentan in Pulmonary Arterial Hypertension, Randomized, Double-Blind, Placebo-Controlled, Multicenter, Efficacy Study; STRIDE: Sitaxsentan To Relieve Impaired Exercise; SUPER: Sildenafil Use in Pulmonary Arterial Hypertension; PHIRST: Pulmonary Arterial Hypertension and Response to Tadalafil. ^#: patients were stratified by WHO FC prior to being randomised.