Heart failure (HF) is a complex syndrome that has a poor prognosis and a stigma of high mortality. The current prevalence estimated in the United States is six million cases, with a predicted incidence of another two million patients until 2030. Brazil, specifically, had more than 26 thousand deaths by HF in 2012 and approximately 230 thousand hospitalizations attributed to this disease.

The main HF symptoms include progressive dyspnea, fatigue, exercise intolerance, and signs of volume overload, reducing the functional capacity and quality of life of patients and greatly increasing the risk of morbidity and mortality. In this regard, a peak oxygen consumption (maxVO₂), on average, approximately 50% lower is not uncommon in HF patients when compared to healthy individuals paired by variables such as age and gender. The cardiopulmonary exercise testing (CPET) is a method widely used and trusted in this scenario, with a consistent role in risk stratification of HF patients and various variables obtained with consolidated prognostic value. MaxVO₂ is an important marker of one-year mortality, surpassing ejection fraction and pulmonary capillary wedge pressure, used as Class I to define candidates for heart transplantation. Other prognostic markers obtained from CPET that proved to be important in this population include the measurement of ventilatory efficiency through the VE/VCO₂ slope, regular ventilation, oxygen uptake efficiency slope (OUES), heart rate recovery (HRR) in the first minute, chronotropic competence, and partial pressure of carbon dioxide at rest (PetCO₂).^,

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