title: Oxygen uptake efficiency slope correlates with brain natriuretic peptide in patients with heart failure.
abstract: 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 VO(2) (17.1 +/- +/- 5.1 vs 36.9 +/- 4.9 mL/kg/min), O(2) pulse (10.9 +/- 3.3 vs 15.9 +/- 2.7) and VE/VCO(2) 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 VO(2) (r = 0.80), VO(2) AT (r = 0.65) and VE/VCO(2) 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 VO(2) 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.
authors.affiliation: 1st Department of Cardiology, University School of Medical Sciences, Długa 1/2, Poznań, Poland. ewa.migaj-straburzynska@skpp.edu.pl
authors.forename: Ewa
authors.initials: E
authors.lastname: Straburzyńska-Migaj
authors.forename: Adrian
authors.initials: A
authors.lastname: Gwizdała
authors.forename: Andrzej
authors.initials: A
authors.lastname: Siniawski
authors.forename: Romuald
authors.initials: R
authors.lastname: Ochotny
authors.forename: Stefan
authors.initials: S
authors.lastname: Grajek
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002908:Chronic Disease; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D011044:Poland; D011237:Predictive Value of Tests; D011379:Prognosis; D012123:Pulmonary Ventilation; D012044:Regression Analysis; D013318:Stroke Volume; D016277:Ventricular Function, Left
chemical_list: D015415:Biomarkers; D020097:Natriuretic Peptide, Brain; D010100:Oxygen