Clinical features and determinants of VO2peak in de novo heart transplant recipients

Table 2 Cardiopulmonary responses to exercise of the study population

2N = 63-81	Total	Low-capacity groupVO2peak ≤ 19.4 mL/kg per min (n = 41)	High-capacity groupVO2peak > 19.4 mL/kg per min (n = 40)	t(P-value)	Univariate regressionStandardized coefficientBeta [95%CI], PVO2peak L/min	3R2
VO2peak (mL/kg per min)	20.4 ± 4.9	16.4 ± 2	24.3 ± 3.6	< 0.001	0.75 [0.05, 0.08], < 0.001	0.56
VO2peak (L/min)	1.6 ± 0.4	1.3 ± 0.3	1.8 ± 0.4	< 0.001
%expected VO2peak	55.8 ± 12.4	46.5 ± 7.4	65.3 ± 8.6	< 0.001	0.60 [0.01, 0.03], < 0.001	0.36
RER	1.2 ± 0.1	1.2 ± 0.14	1.2 ± 0.10	0.898
HRrest (echocardiography)	87 ± 10	87 ± 11	86 ± 9	0.85	-0.07 [-0.013, 0.007], 0.551	0.01
Peak systolic BP (mmHg)	188 ± 30	188 ± 31	189 ± 30	0.865	0.19 [-0.001, 0.006], 0.108	0.04
Peak diastolic BP (mmHg)	82 ± 17	82 ± 18	82 ± 16	0.917	0.09 [-0.004, 0.008], 0.467	0.01
VE/VCO2slope	34.8 ± 7.7	37.3 ± 7.2	32.6 ± 7.6	0.008	-0.42 [-0.035, -0.01], < 0.001	0.18
Vmax (L)	71.4 ± 22.8	60.5 ± 17.5	81.7 ± 22.7	< 0.001	0.76[0.01, 0.02], < 0.001	0.58
O2 pulse (mL/beat)	12.4 ± 3.3	11.0 ± 3	13.7 ± 3	< 0.001	0.80 [0.08, 0.12], < 0.001	0.65
AT (L/min)	1.08 ± 0.3	0.95 ± 0.2	1.2 ± 0.3	0.001	0.73 [0.74, 1.2], < 0.001	0.53
METS	6.5 ± 1.6	5.4 ± 0.8	7.8 ± 1.3	< 0.001	0.77 [0.16, 0.24], < 0.001	0.59
HRpeak (beats/min)	128 ± 19	121 ± 19	134 ± 17	0.001	0.31 [0.002, 0.01], 0.005	0.1
%HRmax	75 ± 12	72 ± 12	78 ± 11	0.021	0.20 [-0.001, 0.02], 0.071	0.04
HRreserve (beats/min)	43 ± 16	35 ± 13	50 ± 15	< 0.001	0.47 [0.01, 0.02], < 0.001	0.22
CRI	0.51 ± 0.2	0.45 ± 0.18	0.57 ± 0.2	0.004	0.31 [0.20, 1.12], 0.005	0.1
RPE (Borg scale)	18.6 ± 0.8	18.5 ± 1	18.6 ± 0.5	0.638
Test duration (min)	9.5 ± 2.8	7.8 ± 1.5	11.1 ± 2.7	< 0.001
HRrecovery
Beats /min at 2 min	-1.0 (-3.0, 1.0)	-1.0 (-3.0, 1.0)	-2.0 (-3.3, 1.3)	0.6971

Groups are divided according to the median VO_2peak (mL/kg per min). Variables are presented as mean ± SD or as median (Q1, Q3) where appropriate.

¹Mann Whitney U-test;

²The actual N varies from 63 to 81 for different variables;

³Unadjusted R². BP: Blood pressure; CI, confidence interval; CRI, chronotropic response index; HR, heart rate; METS, metabolic equivalents; Vmax, maximum ventilation; Q1, first quartile; Q3, third quartile; RER, Respiratory Exchange Ratio; RPE, rated perceived exertion; SD, standard deviation.