Lung Fluid Volume during Cardiopulmonary Exercise Testing

Background and Objectives: Cardiopulmonary exercise testing can be used to quantify exercise capacity in patients with heart failure with reduced ejection fraction (HfrEF). Lung fluid levels as measured non-invasively by remote dielectric sensing (ReDS(TM)), often correlate with intracardiac filling pressures. The change in lung fluid levels in patients with HfrEF during cardiopulmonary exercise testing is unknown. Materials and Methods: Patients with chronic HfrEF who underwent cardiopulmonary exercise testing between October 2021 and March 2022 were prospectively included in this proof-of-concept study, with ReDS values measured before and after testing. Results: Thirteen patients (median age 41 (37, 52) years, 69% men, plasma B-type natriuretic peptide 141 (57, 368) pg/mL) were included. Median peak oxygen consumption was 11.4 (10.7, 14.0) mL/kg/min. During the test, ReDS values increased from 25% to 32% only in one patient on inotropic support, whereas ReDS values remained unchanged in the other 12 patients. The former patient remained hospitalized, whereas the other patients were dischargeable without any new incidence of clinical events during the observational period (median duration 69 (33, 112] days). Conclusions: The ReDS system may be a feasible complementary tool to noninvasively assess the changes in lung fluid levels during cardiopulmonary exercise testing. The clinical implications of ReDS values during exercise needs further investigation.