Exercise intensity prescription in heart failure: A comparison of different physiological parameters

Introduction and objective: Aerobic exercise intensity prescription is critical for the efficacy and safety of heart failure (HF) patients’ rehabilitation programs. This study aims to compare some of the commonly used parameters for range-based exercise intensity prescription, with a ventilatory threshold-based approach. Methods: We retrospectively analyzed data from 163 HF patients across a left ventricle ejection fraction (LVEF) spectrum who underwent maximal cardiopulmonary exercise testing (CPET). We measured percentages of peak oxygen uptake (VO₂), peak heart rate (HR) and heart rate reserve (HRR) at the first ventilatory threshold (VT1). We compared the classification within the different exercise intensity (EI) domains defined by the current guidelines. Results: VT1 was observed at 82 ± 10% of peak HR, 54 ± 25% of HRR and 54 ± 17% of peak VO₂, corresponding to the high intensity for % Peak HR, and moderate intensity domain for %HRR and % Peak VO₂. Using % Peak VO₂, 65% of the patients were accurately classified within the correct EI domain (moderate intensity) at VT1; however, this percentage dropped to 46% when employing %HRR and to 25% when using % Peak HR. The classification accuracy at VT1 was superior in patients with reduced LVEF and in those with higher exercise capacity. Conclusion: Our data show that EI will be misclassified in one out of three patients if guided by current guideline-recommended range-based parameters, which emphasizes the relevance of a ventilatory threshold-based approach to adequate exercise prescription in HF patients.