We investigated the correlations between exercise intolerance and the plasma levels of neurohormonal factors and proinflammatory cytokines in chronic heart failure (CHF) patients.
Sixty-two CHF patients who underwent cardiopulmonary exercise testing (CPX) were enrolled in this study. Peak oxygen uptake (peak VO₂) and the plasma concentrations of noradrenaline (NA), brain natriuretic peptide (BNP), and soluble tumor necrosis factor receptors I and II (TNFR-I and -II) were all measured during the CPX. The patients were divided into three groups according to their peak VO₂; a severe exercise intolerance group (severe group; peak VO₂ < 18 mL/min/kg), moderate exercise intolerance group (moderate group; 18 ≤ peak VO₂ ≤ 24), and mild exercise intolerance group (mild group; peak VO₂ > 24).
There were no significant differences in left ventricular ejection fraction (EF) among the three groups. NA and BNP both increased gradually in parallel with the worsening of exercise intolerance (NA, 211.5 ± 75.7 pg/mL, 331.8 ± 163.7, 441.9 ± 202.9, respectively; BNP, 37.9 ± 25.4 pg/mL, 148.9 ± 117.1, 247.9 ± 150.0, respectively). TNFR-I and II were significantly higher in the severe group than in the moderate group (1746.1 ± 950.7 versus 1085.2 ± 370.5 pg/mL and 2855.3 ± 1550.9 versus 2047.7 ± 648.7 pg/mL, respectively), while the values in the moderate group were not significantly different from those in the mild group. EF showed no significant correlations with NA, BNP, TNFR-I, or TNFR-II, whereas peak VO₂ exhibited significant negative correlations with NA (r = −0.50, P < 0.0001), BNP (r = −0.53, P < 0.0001), TNFR-I (r = −0.50, P < 0.0001), and TNFR-II (r = −0.45, P < 0.0001).
It is concluded that NA and BNP rise in parallel with the degree of exercise intolerance, while TNFR-I and -II rise only when exercise intolerance reaches severe levels.