Quantifying Symptoms and Effort in Heart Failure: the Need for a Common Language through Cardiopulmonary Exercise Testing

Extract In recent years, we have observed a growing scientific interest in physical exercise and functional capacity in heart failure (HF) patients, leading scientific communities to increasingly regard structured training and physical activity not only as safe habits, but also as robust therapeutic tools. In this field, the aim of exercise goes far beyond the prevention of cardiovascular diseases, being the only way to counteract deconditioning. Cardiopulmonary exercise test (CPET) is recognized as the gold-standard technique for assessing exercise intolerance and for the differential diagnosis of exertional dyspnoea in HF, regardless of its aetiology or phenotype (i.e. reduced vs. preserved ejection fraction).1 It also holds important prognostic value and is essential for evaluating therapeutic response and guiding exercise prescription.1 Despite this, most clinical trials investigating treatment effects in HF still rely on exercise intolerance using patients’ self-reported symptoms, like in the New York Heart Association (NYHA) classification, the Kansas City Cardiomyopathy Questionnaire (KCCQ), the Minnesota Living with Heart Failure Questionnaire (MLHFQ), or the Borg scale for exertional dyspnoea.2 Each study adopts its own endpoint—often composite by necessity—to assess patients’ quality of life (QoL) and symptoms, resulting in measures that differ substantially across trials. Quantifying QoL is fundamental, especially from the patient’s perspective, as living well is often perceived as an outcome that can be as important as the strongest endpoints, such as mortality or HF hospitalization. However, this purely subjective assessment is complex and should be adapted according to the specific characteristics of the study population. In addition to the disease-specific questionnaires mentioned above, generic instruments such as the Duke Activity Status Index, EuroQol 5 Dimensions (EQ-5D) and the SF-36 are sometimes used, allowing for cross-disease comparisons.3 These tools assess multiple domains, including physical symptoms, functional limitations, emotional and social well-being, and are frequently employed as secondary or co-primary endpoints in clinical trials.