Elsevier

American Heart Journal

Volume 147, Issue 2, February 2004, Pages 354-360
American Heart Journal

Clinical investigation: imaging and diagnostic testing
Peak VO2 and VE/VCO2 slope in patients with heart failure: a prognostic comparison

https://doi.org/10.1016/j.ahj.2003.07.014Get rights and content

Abstract

Background

Exercise testing with ventilatory expired gas analysis has proven to be a valuable tool for assessing patients with heart failure (HF). Peak oxygen consumption (peak VO2) continues to be considered the gold standard for assessing prognosis in HF. The minute ventilation − carbon dioxide production relationship (VE/VCO2 slope) has recently demonstrated prognostic significance in patients with HF, and in some studies, it has outperformed peak VO2.

Methods

Two hundred thirteen subjects, in whom HF was diagnosed, underwent exercise testing between April 1, 1993, and October 19, 2001. The ability of peak VO2 and VE/VCO2 slope to predict cardiac-related mortality and hospitalization was examined.

Results

Peak VO2 and VE/VCO2 slope were demonstrated with univariate Cox regression analysis both to be significant predictors of cardiac-related mortality and hospitalization (P <.01). Multivariate analysis revealed that peak VO2 added additional value to the VE/VCO2 slope in predicting cardiac-related hospitalization, but not cardiac mortality. The VE/VCO2 slope was demonstrated with receiver operating characteristic curve analysis to be significantly better than peak VO2 in predicting cardiac-related mortality (P <.05). Although area under the receiver operating characteristic curve for the VE/VCO2 slope was greater than peak VO2 in predicting cardiac-related hospitalization (0.77 vs 0.73), the difference was not statistically significant (P = .14).

Conclusions

These results add to the present body of knowledge supporting the use of cardiopulmonary exercise testing in HF. Consideration should be given to revising clinical guidelines to reflect the prognostic importance of the VE/VCO2 slope in addition to peak VO2.

Section snippets

Methods

Two hundred thirteen subjects, assessed between April 1, 1993, and October 19, 2001, were included in the study. One hundred forty-four subjects underwent exercise testing and were subsequently observed at the Veterans Hospital in Palo Alto, Calif. The remaining 69 subjects were tested and observed in the heart failure program at the Virginia Commonwealth University Medical Center in Richmond. All subjects underwent tested on an outpatient basis. The exercise tests were conducted as part of the

Results

The mean follow-up period was 32 ± 26 months, and the annual mortality rate was 5.4%. Mean values for peak VO2 and VE/VCO2 slope were 16.3 ± 6.0 mL × kg−1 × min−1 and 33.2 ± 7.9 mL × kg−1 × min−1, respectively. On the basis of individual peak VO2 values, the Weber classification for the group was: Weber class A, 51; Weber class B, 47; Weber class C, 89; Weber class D, 26. There were 15 cardiac-related deaths and 61 cardiac-related hospitalizations within 1-year after exercise testing. Overall,

Discussion

The results of this study add to a growing body of data demonstrating the prognostic value of peak VO2 and VE/VCO2 slope in the HF population.3, 8, 9, 10, 11, 12, 13 More importantly, these results support the concept that the VE/VCO2 slope is prognostically superior to peak VO2, an observation made recently by other investigators, although not overly emphasized.3, 8, 10, 11, 14

There may be several reasons for the differences between the prognostic value of the VE/VCO2 slope and peak VO2. Peak

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