Background: Cardiopulmonary exercise testing is a well-established tool for clinical and
prognostic assessment of patients with chronic heart failure (CHF). Recently, a new parameter
of this examination - oxygen uptake efficiency slope (OUES) - has been described and
proposed as a new prognostic factor in patients with CHF. Brain natriuretic peptide (BNP) is
an established prognostic factor in CHF. The purpose of the study was to assess OUES in
patients with CHF in relation to other cardiopulmonary parameters and BNP levels.
Methods: The study group consisted of 42 patients with CHF and left ventricular ejection
fraction (LVEF) < 45% (mean age 50.2 ± 9.3 years, mean ejection fraction 26.1 ± 8.1% and
NYHA functional class - 2.5 ± 0.8) and eight healthy controls (age 43.6 ± 14.7 years).
Coronary artery disease was diagnosed in 16 patients (38%). All underwent maximal cardiopulmonary
exercise treadmill test. BNP level was measured using Abbott AxSYM Immunoassay
system.
Results: There were significant (p < 0.001) differences between the patients and controls in
BNP levels (350 ± 520 vs 14 ± 19 pg/mL), OUES (1.7 ± 0.4 vs 2.7 ± 0.5), peak VO2 (17.1 ±
± 5.1 vs 36.9 ± 4.9 mL/kg/min), O2 pulse (10.9 ± 3.3 vs 15.9 ± 2.7) and VE/VCO2 slope
(35.7 ± 7.8 vs 25.7 ± 2.7). In patients, OUES was significantly (p < 0.001) correlated with
LVEF (r = 0.54), BNP levels (r = -0.49), peak VO2 (r = 0.80), VO2 AT (r = 0.65) and
VE/VCO2 slope (r = -0.59). BNP was independently related to OUES in multivariate regression
analysis.
Conclusions: Oxygen uptake efficiency slope is significantly reduced in patients with CHF
and correlates with peak VO2 and other parameters of cardiopulmonary exercise treadmill test.
It is not related to age. BNP is an independent marker of OUES in patients with CHF.
(Cardiol J 2010; 17, 4: 362-366