title: VE/VCO2 slope in older heart failure patients with normal versus reduced ejection fraction compared with age-matched healthy controls.
abstract: BACKGROUND
  Oxygen consumption (VO2) has previously been used for prognosis and risk stratification in patients with heart failure. More recent research has introduced VE/VCO2 slope as a prognostic measure. Risk of mortality is thought to increase when VE/VCO2 slope values are greater than 34. Therefore, the purpose of this study was to cross-sectionally examine VE/VCO2 slope in systolic heart failure (SHF) and diastolic heart failure (DHF) as well as age-matched healthy controls.
  
  
  RESULTS
  Maximal graded exercise tests were conducted on 147 patients (59 DHF, 60 SHF, and 28 controls) using a bicycle ergometer. Breath-by-breath expired gas analysis was performed using a commercially available system with on-line computer calculations. VE/VCO2 slope was calculated from a regression line of minute ventilation and carbon dioxide production. One-way analysis of covariance with a Bonferroni post hoc test and Pearson correlations were used for statistical analysis. VE/VCO2 slope was significantly higher in SHF when compared to both DHF (37 +/- 8 vs. 34 +/- 7, P = .03) and controls (37 +/- 8 vs. 32 +/- 5, P = .002). No significant difference was observed between DHF and healthy controls (34 +/- 7 vs. 32 +/- 5, P = .52). Additional analysis resulted in significant correlations between VO2 and VE/VCO2 slope in systolic heart failure patients (r = -0.40, P = .002); however, there was no significant relationships in diastolic heart failure patients (r = -0.09, P = .49) or in controls (r = 0.13, P = .50).
  
  
  CONCLUSIONS
  VE/VCO2 slope is significantly higher in patients with SHF compared with DHF and healthy controls.
authors.affiliation: Section on Cardiology, Department of Internal Medicine, Wake Forest University, Winston-Salem, North Carolina, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Moore
authors.forename: Peter H
authors.initials: PH
authors.lastname: Brubaker
authors.forename: Kathryn P
authors.initials: KP
authors.lastname: Stewart
authors.forename: Dalane W
authors.initials: DW
authors.lastname: Kitzman
mesh_terms: D000367:Age Factors; D000368:Aged; D003430:Cross-Sectional Studies; D003971:Diastole; D005080:Exercise Test / Q000379:methods; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology; D013599:Systole