VE/VCO2 slope in older heart failure patients with normal versus reduced ejection fraction compared with age-matched healthy controls

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. Methods and 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 Benferroni 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.