Table 2.

Relative ranking of cardiopulmonary exercise test variables based on and their association^a to a composite outcome of death, left ventricular assist device implant, or heart transplant in patients with heart failure with reduced ejection fraction

Ranking	Variable	Wald X2	P
1	% predicted maximum VO2	203	< 0.001
2	VE/VCO2 slope	201	< 0.001
3	Peak oxygen uptake efficiency (OUE) ratio	184	< 0.001
4	Peak VE/VCO2	179	< 0.001
5	VE/VCO2 slope/peak VO2	168	< 0.001
6	Peak VO2 (mL·min−1)	166	< 0.001
7	Peak VO2 (mL·kg−1·min−1)	161	< 0.001
8	Oxygen uptake efficiency slope (OUES)	154	< 0.001
9	Circulatory powerb	143	< 0.001
10	Ventilatory powerc	140	< 0.001
11	Peak end-tidal CO2	111	< 0.001
12	Peak O2 pulse	97	< 0.001
13	Peak rate-pressure product	92	< 0.001
14	Peak heart rate	66	< 0.001
15	Heart rate reserve (peak-rest)	61	< 0.001
16	Peak systolic blood pressure	60	< 0.001
17	% predicted maximum heart rate	52	< 0.001
18	Chronotropic index	51	< 0.001
19	Peak ventilation	47	< 0.001
20	Systolic blood pressure reserve (peak-rest)	42	< 0.001
21	Peak mean arterial blood pressure	40	< 0.001
22	Peak mean arterial blood pressure reserve (peak-rest)	22	< 0.001
23	Test limited by shortness of breath	16	< 0.001
24	Rest SBP < 100 mmHg	16	< 0.001
25	Exercise oscillatory ventilation	13	< 0.001
26	Heart rate recovery at 2 min < 22 beats	9	0.002
27	Heart rate recovery at 1 min < 12 beats	7	0.009
28	Peak respiratory exchange ratio < 1	5	0.021

Adapted from Brawner et al. [33]

^aBased on a Cox regression analysis adjusted for age, sex, ejection fraction, and beta-adrenergic blockade therapy

^bCirculatory power = peak VO₂ (mL·kg⁻¹·min⁻¹) × peak systolic blood pressure

^cVentilatory power = peak systolic blood pressure/V_E/VCO₂ slope