Cardiopulmonary exercise testing (CPET) is a valuable tool for assessing and managing heart failure (HF) patients. It measures respiratory and cardiac responses to exercise, providing key parameters such as oxygen uptake (VO₂ max) and the relationship between minute ventilation (VE) and carbon dioxide excretion (VCO₂). These parameters help classify patients and predict prognosis. Patients with VO₂ <14 mL/kg/min and VE/VCO₂ slope >35 have a poor prognosis. CPET is used in drug trials to evaluate the effects of medications like ACE inhibitors, which improve exercise capacity and reduce the VE/VCO₂ slope. Chronic HF and reduced physical activity are associated with increased BNP levels, and cardiac rehabilitation reduces BNP and increases VO₂. MicroRNA measurements can assess skeletal muscle status and rehabilitation outcomes. CPET requires complex technology, but portable devices and smart watches can provide real-time data for better patient management. This review discusses CPET's role in HF classification, exercise principles, clinical applications, and prognosis. It highlights the importance of CPET parameters like VO₂ max, VE/VCO₂ slope, RER, and PETCO₂ in risk stratification and treatment decisions. CPET is essential for evaluating drug efficacy, monitoring treatment responses, and guiding cardiac rehabilitation. Biomarkers like BNP and miRNAs provide insights into physical capacity and rehabilitation outcomes. Overall, CPET is a critical tool for improving HF management through objective assessment and personalized treatment strategies.Cardiopulmonary exercise testing (CPET) is a valuable tool for assessing and managing heart failure (HF) patients. It measures respiratory and cardiac responses to exercise, providing key parameters such as oxygen uptake (VO₂ max) and the relationship between minute ventilation (VE) and carbon dioxide excretion (VCO₂). These parameters help classify patients and predict prognosis. Patients with VO₂ <14 mL/kg/min and VE/VCO₂ slope >35 have a poor prognosis. CPET is used in drug trials to evaluate the effects of medications like ACE inhibitors, which improve exercise capacity and reduce the VE/VCO₂ slope. Chronic HF and reduced physical activity are associated with increased BNP levels, and cardiac rehabilitation reduces BNP and increases VO₂. MicroRNA measurements can assess skeletal muscle status and rehabilitation outcomes. CPET requires complex technology, but portable devices and smart watches can provide real-time data for better patient management. This review discusses CPET's role in HF classification, exercise principles, clinical applications, and prognosis. It highlights the importance of CPET parameters like VO₂ max, VE/VCO₂ slope, RER, and PETCO₂ in risk stratification and treatment decisions. CPET is essential for evaluating drug efficacy, monitoring treatment responses, and guiding cardiac rehabilitation. Biomarkers like BNP and miRNAs provide insights into physical capacity and rehabilitation outcomes. Overall, CPET is a critical tool for improving HF management through objective assessment and personalized treatment strategies.