Responses to exercise training in patients with heart failure. Analysis by oxygen transport steps

Background: Exercise training (ET) increases exercise tolerance, improves quality of life and likely the prognosis in heart failure patients with reduced ejection fraction (HFrEF). However, some patients do not improve, whereas exercise training response is still poorly understood. Measurement of cardiac output during cardiopulmonary exercise test might allow ET response assessment according to the different steps of oxygen transport. Methods: Fifty-three patients with HFrEF (24 with ischemic cardiomyopathy (1CM) and 29 with dilated cardiomyopathy (DCM) had an aerobic ET. Before and after ET program, peak oxygen consumption (VO2peak) and cardiac output using thoracic impedancemetry were measured. Oxygen convection (VO2peak) and diffusion (DO2) were calculated using Fick's principle and Fick's simplified law. Patients were considered as responders if the gain was superior to 10%. Results: We found 55% VO2peak responders, 62% QO(2peak) responders and 56% DO2 responders. Four patients did not have any response. None baseline predictive factor for VO2peak response was found. QO(2peak) response was related to exercise stroke volume (r = 0.84), cardiac power (r = 0.83) and systemic vascular resistance (SVRpeak) (r = -0.42) responses. Cardiac power response was higher in patients with ICM than in those with DCM (p < 0.05). Predictors of QO2(peak) response were low baseline exercise stroke volume and ICM etiology. Predictors of DO2 response were higher baseline blood creatinine and prolonged training. Conclusion: The analysis of the response to training in patients with HFrEF according to the different steps of oxygen transport revealed different phenotypes on VO2peak, responses, namely responses in either oxygen convection and/or diffusion. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study found that heart failure patients have different responses to exercise training in terms of oxygen transport, including oxygen convection and diffusion. Some patients responded positively to exercise training, while others did not show significant improvement.