Elsevier

American Heart Journal

Volume 160, Issue 6, December 2010, Pages 1004-1014
American Heart Journal

Curriculum in Cardiology
Prediction of severe cardiovascular events by VE/Vco2 slope versus peak Vo2 in systolic heart failure: A meta-analysis of the published literature

https://doi.org/10.1016/j.ahj.2010.08.037Get rights and content

Background

Peak Vo2 has traditionally been used for prognostic evaluation in systolic heart failure. However, in the past years, VE/Vco2 slope has been shown to be similar or even superior in many studies. We performed a systematic review and a meta-analysis of diagnostic studies of VE/Vco2 slope to assess its ability to predict cardiovascular events in systolic heart failure.

Methods

We searched the published literature in PubMed and ISI Web of Science for VE/Vco2 slope in heart failure, and performed a systematic review and a meta-analysis of diagnostic studies in articles fulfilling previously established selection criteria. End points were serious cardiovascular events defined as death or the combined end point of death, ventricular assist device implantation, or heart transplant. A sub-analysis was also performed with those articles providing enough data to compare VE/Vco2 slope prognostic ability to that of peak Vo2.

Results

Four hundred ninety-one articles that are potentially relevant were identified, and 12 studies were selected based on our predefined criteria. No heterogeneity or evidence of publication bias was found. The 12 studies included a total of 2,628 patients with a mean follow-up of 31 months (95% CI 16-46 months). The combined event rate at 1 year was 11.2% (95% CI 7.8%-14.6%). Diagnostic odds ratio and area under the curve for serious cardiovascular events were 5.02 (95% CI 4.06-6.21) and 0.75 (95% CI 0.72-0.78), respectively. Six studies provided sufficient data for VE/Vco2 slope and peak Vo2 comparison. Both variables showed similar performance, although VE/Vco2 did present a trend to superiority.

Conclusions

In this meta-analysis, VE/Vco2 slope represents a reasonable ability to predict serious cardiovascular events in systolic heart failure, and is at least as effective as peak Vo2.

Section snippets

Methods

We conducted a search in PubMed and ISI Web of Science. In PubMed, the search was done following the criteria of Table I, in agreement with current recommendations for meta-analysis of diagnostic studies.11, 12, 13 Results were limited to human studies published in English, Spanish, and Portuguese. For ISI Web of Science, the following strategy was used: [(Ts = heart failure OR Ts = heart transplantation) AND (Ts = ventilatory efficiency OR Ts = VE/VCO2 OR Ts = VE-VCO2 OR Ts = VE/VCO2) AND

Results

Four hundred ninety-one articles were retrieved after our preliminary search, and 92 were considered potentially relevant based on the title and abstract contents. A careful selection was done from these articles, and 80 were excluded for several reasons. Twelve articles were chosen for final analysis (Figure 1).

Quality assessment proved in general to be fair, with most of the studies presenting a retrospective design and prolonged patient enrollment periods. Although test protocols were poorly

Discussion

The present meta-analysis clearly indicates the importance of measuring VE/Vco2 slope in heart failure. Traditionally, peak Vo2 had been considered as the gold standard variable in CPET for prediction of cardiovascular events. However, its prognostic accuracy has been challenged in the last decade. Many authors have expressed concern on the need to reconsider peak Vo2 efficacy in light of current heart failure treatments, particularly β-blocker use.26, 27, 28 After completing a search of the

Disclosures

The authors declare no conflict of interest.

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