Cardiopulmonary exercise testing and heart failure: a tale born from oxygen uptake.

Since 50 years, cardiopulmonary exercise testing (CPET) plays a central role in heart failure (HF) assessment. Oxygen uptake (VO) is one of the main HF prognostic indicators, then paralleled by ventilation to carbon dioxide (VE/VCO) relationship slope. Also anaerobic threshold retains a strong prognostic power in severe HF, especially if expressed as a percent of maximal VO predicted value.