Table 1. Characteristics of pulmonary arterial hypertension according to New York Heart Association/World Health Organization functional class (NYHA/WHO FC) at diagnosis

Parameter	NYHA/WHO FC			p-value
Parameter	I/II	III	IV	p-value
6MWD n	134	359	55
Distance m	415±86	319±92	192±96	<0.0001
Haemodynamic variables n	162	405	77
P_ra mmHg	6±4	9±5	11±7	<0.0001
P̄_pa mmHg	50±17	56±15	56±13	0.0002
P_pcw mmHg	8±3	8±3	8±4	0.75
Cardiac index L·min⁻¹·m⁻²	2.9±0.9	2.4±0.7	2.1±0.8	<0.0001
S_v,O₂	67±8	62±8	54±9	<0.0001
PVRI mmHg·L·min·m⁻²	15.8±9.7	21.5±9.8	25.5±10.1	<0.0001

Data are presented as mean±sd, unless otherwise stated. 6MWD: 6-min walk distance; P_ra: right atrial pressure; P̄_pa: mean pulmonary arterial pressure; P_pcw: pulmonary capillary wedge pressure; S_v,O₂: venous oxygen saturation; PVRI: pulmonary vascular resistance index. Reproduced from [10] with permission from the publisher.