title: Peak VO2 and VE/VCO2 slope in betablockers era in patients with heart failure: a Brazilian experience.
abstract: BACKGROUND
  Studies have demonstrated that peak oxygen consumption (peak VO2) and the VE/VCO2 slope are predictors of survival in patients with heart failure (HF). However, with the advent of betablockers in the treatment of HF, the prognostic values of peak VO2 and VE/VCO2 slope have not been fully established.
  
  
  OBJECTIVE
  To evaluate the effect of betablocker use on the prognostic value of peak VO2 and VE/VCO2 slope in patients with HF.
  
  
  METHODS
  We studied 391 patients with heart failure, aged 49 +/- 14 years and presenting a left ventricular ejection fraction of 38 +/- 10%. The total number of patients that used (Group I - GI) or did not use (Group II - GII) betablockers was 229 and 162, respectively. All patients were submitted to a cardiopulmonary stress test on a treadmill, using the Naughton protocol.
  
  
  RESULTS
  A peak VO2 < or = 10 ml x kg(-1) x min(-1) identified high-risk patients, whereas values > 16 ml x kg(-1) min(-1) categorizes patients with a better mid-term prognosis. Peak VO2 values between > 10 and < or = 16 ml x kg(-1) x min(-1) indicated moderate risk for cardiac event in four years of follow up. The betablocker use significantly reduced the VE/VCO2 slope in patients with HF. The prognostic value of the VE/VCO2 slope < 34 in the group using betablocker can reflect the impact of the drug on this cardiorespiratory variable.
  
  
  CONCLUSIONS
  A low peak VO2 and an elevated VE/VCO2 slope are strong and independent predictors of cardiac events in HF. Thus, both variables remain important survival predictors in patients with HF, especially at the age of betablockers.
authors.affiliation: Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil. gvguima@usp.br
authors.forename: Guilherme Veiga
authors.initials: GV
authors.lastname: Guimarães
authors.forename: Mário Sérgio Vaz da
authors.initials: MS
authors.lastname: Silva
authors.forename: Veridiana Moraes
authors.initials: VM
authors.lastname: d'Avila
authors.forename: Silvia Moreira Ayub
authors.initials: SM
authors.lastname: Ferreira
authors.forename: Christiano Pereira
authors.initials: CP
authors.lastname: Silva
authors.forename: Edimar Alcides
authors.initials: EA
authors.lastname: Bocchi
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D001938:Brazil; D002245:Carbon Dioxide / Q000378:metabolism*; D004812:Epidemiologic Methods; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000188:drug therapy* / Q000209:etiology / Q000401:mortality; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011379:Prognosis
chemical_list: D000319:Adrenergic beta-Antagonists; D002245:Carbon Dioxide