Three Weeks of Inpatient Cardiac Rehabilitation Improves Metabolic Exercise Data Combined With Cardiac and Kidney Indexes Scores for Heart Failure With Reduced Ejection Fraction.

Background: Heart failure with reduced ejection fraction (HFrEF) has a high mortality rate, and cardiac rehabilitation programs (CRP) reduce HFrEF rehospitalization and mortality rates. Some countries attempt 3 weeks of inpatient CRP (3w In-CRP) for cardiac diseases. However, whether 3w In-CRP reduces the prognostic parameter of the Metabolic Exercise data combined with Cardiac and Kidney Indexes (MECKI) score is unknown. Therefore, we investigated whether 3w In-CRP improves MECKI scores in patients with HFrEF. Methods and Results: This study enrolled 53 patients with HFrEF who participated in 30 inpatient CRP sessions, consisting of 30 min of aerobic exercise twice daily, 5 days a week for 3 weeks, between 2019 and 2022. Cardiopulmonary exercise tests and transthoracic echocardiography were performed, and blood samples were collected, before and after 3w In-CRP. MECKI scores and cardiovascular (CV) events (heart failure rehospitalization or death) were evaluated. The MECKI score improved from a median 23.34% (interquartile range [IQR] 10.21-53.14%) before 3w In-CRP to 18.66% (IQR 6.54-39.94%; P<0.01) after 3w In-CRP because of improved left ventricular ejection fraction and percentage peak oxygen uptake. Patients' improved MECKI scores corresponded with reduced CV events. However, patients who experienced CV events did not have improved MECKI scores. Conclusions: In this study, 3w In-CRP improved MECKI scores and reduced CV events for patients with HFrEF. However, patients whose MECKI scores did not improve despite 3w In-CRP require careful heart failure management.