Table 2.

Percent change from baseline in cardiopulmonary exercise parameters at week 16 and year 1 of Sildenafil in Treatment-Naïve Children, Aged 1–17 years, with Pulmonary Arterial Hypertension (STARTS-1/-2)

CPET parameter	Week 16				Year 1
	Placebo (n=30)	Low (n=28)	Medium (n=28)	High (n=29)	Placebo* (n=29)	Low (n=28)	Medium (n=28)	High (n=29)
Peak VO2
N	29	24	26	27	23	25	25	27
Mean	0.5	6.4	13.4	10.6	−0.2	12.4	7.3	5.3
SD	15.9	20.2	19.5	15.5	19.9	22.8	33.8	23.5
VE/VCO2 slope
N	29	23	26	27	23	25	24	26
Mean	2.7	−8	−8.2	−9.6	2.3	−5.2	−5.5	−0.3
SD	12.3	13.4	11.1	14.5	14.5	17.9	17.1	29.1
Respiratory exchange ratio
N	29	24	26	27	23	25	25	27
Mean	−2.7	0	−4.0	−2.0	2.5	2.2	5.6	0.7
SD	10.4	11.7	10.7	10.3	13.8	8.7	13.4	11.5
Time to peak VO2
N	29	24	26	27	23	25	25	27
Mean	4.5	15.2	16.0	11.2	15.2	25.5	13.1	7.7
SD	34.9	26.3	22.9	28.6	65.7	35.7	33.4	33.0
Total ventilation
N	29	23	26	27	23	25	25	26
Mean	4.0	−2.8	4.5	6.1	14.2	15.3	14.7	11.3
SD	20.9	24.7	19.1	21.4	23.7	22.6	35.1	19.4
End-tidal O2
N	19	12	14	15	12	14	10	11
Mean	–1.5	–2.2	–1.2	–2.3	–1.5	0	0.5	–0.3
SD	3.9	3.8	3.2	5.8	4.3	3.1	3.5	4.0
End-tidal CO2
N	19	12	12	13	12	14	9	8
Mean	− 1.6	13.0	− 0.3	4.3	6.9	9.1	4.1	10.3
SD	9.3	18.2	6.6	13.9	14.2	18.9	17.8	33.4
Anaerobic threshold
N	26	20	22	25	20	22	21	22
Mean	5.7	8.3	9.7	6.6	4.6	−1.2	2.0	3.3
SD	25.2	26.6	28.5	24.0	25.0	23.1	29.5	29.4
Percent predicted peak VO2
N	29	24	26	27	23	25	25	27
Mean	0.7	6.6	12.9	10.9	1.0	12.8	7.7	5.8
SD	16.0	19.7	19.4	16.4	20.2	22.7	34.5	23.6

*Parenthesis show values for placebo-treated STARTS-1 patient subsequently randomised in STARTS-2 to sildenafil low, medium or high dose.

CO₂, carbon dioxide production; CPET, cardiopulmonary exercise test; VE, ventilation; VO₂, oxygen consumption.