Increased Left Ventricular Stiffness Impairs Exercise Capacity in Patients with Heart Failure Symptoms Despite Normal Left Ventricular Ejection Fraction

Table 4

Indices of cardiopulmonary exercise testing (variable expressed as median [25–75% quartile]).

	Patient population; (𝑛=39)	DHF; (𝑛=27)	noDHF; (𝑛=12)	P
Performance, watt	117 [90–159]	108 [87–146]	148 [103–196]	.046
Heart rate, 1/min	138 [119–162]	133 [112–148]	150 [128–166]	.110
VO2, mL/min/kg	18 [16–20]	16 [14–19]	21.5 [18.5–27]	<.001
O2 pulse, mL/beat	11.6 [9.2–13.2]	11.6 [9.2–13]	11.5 [9–13.5]	.715
VO2/exercise level, mL/min/Watt	9.6 [8.4–10.8]	9.7 [8.3–11.5]	9.2 [8.4–9.8]	.161
Breathing reserve, L	64 [42–83]	57 [37–72]	81 [74–98]	.006
Breathing frequency, 1/min	32 [29–37]	32 [29–37]	31 [25–40]	.502
VO2 at VT, L/min	0.96 [0.75–1.25]	0.94 [0.72–1.13]	1.03 [0.82–1.39]	.172
Ventilation equivalents
VECO2 at rest	40 [37–46]	43 [39–49]	37 [34–39]	.002
VECO2 at VT	31 [30–33]	33 [30–36]	31 [24–33]	.023
VEO2 at rest	34 [32–37]	35 [32–39]	34 [29–36]	.138
VEO2 at VT	31 [29–35]	31 [29–35]	31 [23–34]	.423

VO₂ indicates peak oxygen uptake, VT ventilatory threshold, VECO₂ ventilation equivalent for carbon dioxide output, VEO₂ ventilation equivalent for oxygen uptake.