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Randomized Controlled Trial
, 67 (7), 780-9

Variables Measured During Cardiopulmonary Exercise Testing as Predictors of Mortality in Chronic Systolic Heart Failure

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Randomized Controlled Trial

Variables Measured During Cardiopulmonary Exercise Testing as Predictors of Mortality in Chronic Systolic Heart Failure

Steven J Keteyian et al. J Am Coll Cardiol.

Erratum in

  • Correction
    J Am Coll Cardiol 67 (16), 1979-80. PMID 27102522.

Abstract

Background: Data from a cardiopulmonary exercise (CPX) test are used to determine prognosis in patients with chronic heart failure (HF). However, few published studies have simultaneously compared the relative prognostic strength of multiple CPX variables.

Objectives: The study sought to describe the strength of the association among variables measured during a CPX test and all-cause mortality in patients with HF with reduced ejection fraction (HFrEF), including the influence of sex and patient effort, as measured by respiratory exchange ratio (RER).

Methods: Among patients (n = 2,100, 29% women) enrolled in the HF-ACTION (HF-A Controlled Trial Investigating Outcomes of exercise traiNing) trial, 10 CPX test variables measured at baseline (e.g., peak oxygen uptake [Vo2], exercise duration, percent predicted peak Vo2 [%ppVo2], ventilatory efficiency) were examined.

Results: Over a median follow-up of 32 months, there were 357 deaths. All CPX variables, except RER, were related to all-cause mortality (all p < 0.0001). Both %ppVo2 and exercise duration were equally able to predict (Wald chi-square: ∼141) and discriminate (c-index: 0.69) mortality. Peak Vo2 (ml·kg(-1)·min(-1)) was the strongest predictor of mortality among men (Wald chi-square: 129) and exercise duration among women (Wald chi-square: 41). Multivariable analyses showed that %ppVo2, exercise duration, and peak Vo2 (ml·kg(-1)·min(-1)) were similarly able to predict and discriminate mortality. In men, a 10% 1-year mortality rate corresponded to a peak Vo2 of 10.9 ml·kg(-1)·min(-1) versus 5.3 ml·kg(-1)·min(-1) in women.

Conclusions: Peak Vo2, exercise duration, and % ppVo2 carried the strongest ability to predict and discriminate the likelihood of death in patients with HFrEF. The prognosis associated with a given peak Vo2 differed by sex. (Exercise Training Program to Improve Clinical Outcomes in Individuals With Congestive Heart Failure; NCT00047437).

Keywords: peak Vo(2); respiratory exchange ratio; sex; survival.

Figures

FIGURE 1
FIGURE 1. Three-year Survival and Baseline Peak VO2
Using a Cox proportional hazards model, 3-year survival probabilities as a function of baseline peak oxygen uptake (peak VO2) in men and women are similar to those seen at 1 year (Central Illustration). Vertical bars represent 95% confidence intervals.
FIGURE 1
FIGURE 1. Three-year Survival and Baseline Peak VO2
Using a Cox proportional hazards model, 3-year survival probabilities as a function of baseline peak oxygen uptake (peak VO2) in men and women are similar to those seen at 1 year (Central Illustration). Vertical bars represent 95% confidence intervals.
FIGURE 2
FIGURE 2. Survival Rates Categorized by Peak VO2
Kaplan-Meier survival curves stratified based on peak VO2 category (<12, 12–18, >18 mL·kg−1·min−1), both greater than or equal to (A) and less than (B) a respiratory exchange ratio (RER) of 1.05.
FIGURE 2
FIGURE 2. Survival Rates Categorized by Peak VO2
Kaplan-Meier survival curves stratified based on peak VO2 category (<12, 12–18, >18 mL·kg−1·min−1), both greater than or equal to (A) and less than (B) a respiratory exchange ratio (RER) of 1.05.
FIGURE 3
FIGURE 3. CENTRAL ILLUSTRATION One-year Survival and Baseline Peak VO2
This study examined the strength of the association among variables measured during a cardiopulmonary exercise test and all-cause mortality in patients with heart failure with reduced ejection fraction. Peak oxygen uptake (peak VO2) was the strongest predictor of mortality among men and exercise duration among women. When comparing baseline peak VO2, 1-year probability of survival curve as determined using a Cox proportional hazards model varies between men and women. At a peak VO2 of 11 mL·kg−1·min−1, the estimated 1-year mortality rate is <4% in women versus ~10% in men. Vertical bars represent 95% confidence intervals.

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