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Updated: Jun 8, 2026
Home-Based Prescribed Pulmonary Exercise in Patients with Stable Chronic Obstructive Pulmonary Disease
Published on: August 24, 2019
Development of a cardiopulmonary exercise prognostic score for optimizing risk stratification in heart failure: the
Marco Guazzi1, Patrizia Boracchi, Ross Arena
1Cardiopulmonary Unit, University of Milano, Milano, Italy. marco.guazzi@unimi.it
Insights
Exercise periodic breathing (EPB) and elevated minute ventilation/carbon dioxide production (VE/VCO₂) slope are key predictors of cardiac death risk in heart failure (HF) patients. The new PROBE score effectively stratifies risk, improving prognostic accuracy in HF.
Area of Science:
- Cardiology
- Pulmonary Medicine
- Exercise Physiology
Background:
- Cardiopulmonary exercise testing (CPET) is crucial for assessing mortality risk in heart failure (HF).
- Key CPET prognostic markers include peak oxygen consumption (VO₂), VE/VCO₂ slope, and exercise periodic breathing (EPB).
- Optimizing risk stratification in HF patients requires understanding the combined prognostic value of these markers.
Purpose of the Study:
- To determine the relative and additive contributions of peak VO₂, VE/VCO₂ slope, and EPB to cardiac death risk in HF.
- To develop a novel prognostic score for enhanced risk stratification in HF patients undergoing CPET.
Main Methods:
- Prospective tracking of cardiac mortality in 695 stable HF patients who underwent symptom-limited CPET.
- Multivariable Cox analysis to identify independent prognosticators.
- Development of the PROBE score incorporating EPB, VE/VCO₂ slope, and peak VO₂ using statistical bootstrap techniques.
Main Results:
- Exercise periodic breathing (EPB) emerged as the strongest independent prognosticator of cardiac death.
- The PROBE score, integrating EPB and VE/VCO₂ slope, significantly improved prognostic accuracy.
- Higher VE/VCO₂ slope and lower peak VO₂ increased the statistical power of prognostic configurations, with EPB having the greatest impact.
Conclusions:
- The PROBE score, particularly when incorporating EPB and an elevated VE/VCO₂ slope, provides precise risk stratification in HF.
- Peak VO₂ offers minimal additional prognostic information when EPB is present.
- The PROBE score represents an advancement in utilizing CPET for prognostic definition in heart failure.
Background:
Cardiopulmonary exercise testing (CPET) provides powerful information on risk of death in heart failure (HF). We sought to define the relative and additive contribution of the 3 landmark (CPET) prognostic markers--peak oxygen consumption (VO₂), minute ventilation/carbon dioxide production (VE/VCO₂) slope, and exercise periodic breathing (EPB)-to the overall risk of cardiac death and to develop a prognostic score for optimizing risk stratification in HF patients.
Methods And Results:
A total of 695 stable HF patients (average LVEF: 25 ± 8%) underwent a symptom-limited CPET maximum test after familiarization and were prospectively tracked for cardiac mortality. At multivariable Cox analysis EPB emerged as the strongest prognosticator. Using a statistical bootstrap technique (5000 data resamplings), point estimates, and 95% confidence intervals were obtained. Thirty-two configurations were adopted to classify patients into a given cell, according to EPB presence or absence and values of the 2 other covariates. Configurations without EPB and with VE/VCO₂ slope ≤30 were not significantly different from 0 (reference value). Statistical power of configurations increased with higher VE/VCO₂ slope and lower peak VO₂. This prompted us to formulate a score including EPB as a discriminating variable, the (P)e(R)i(O)dic (B)reathing during (E)xercise (PROBE), which ranges between -1 and 1, with zero as reference configuration, that would help to optimize the prognostic accuracy of CPET-derived variables. The greatest PROBE score impact was provided by EPB, followed by VE/VCO₂ slope, whereas peak VO₂ added minimal prognostic power.
Conclusions:
EPB with an elevated VE/VCO₂ slope leads to the highest and most precise PROBE score, whereas no additional risk information emerges when EPB is present with a peak VO₂ ≤10 mL O₂·kg⁻¹·min⁻¹. PROBE score appears to provide a step forward for optimizing CPET use in HF prognostic definition.
