[Impact of empagliflozin on peak oxygen uptake in HFmrEF patients: a randomized controlled trial]

Objective: To evaluate the impact of empagliflozin on peak oxygen uptake (VO₂peak) in patients with heart failure with mildly reduced ejection fraction (HFmrEF). Methods: In this randomized controlled trial, consecutive HFmrEF patients admitted to the Department of Cardiology of China-Japan Friendship Hospital from September 2019 to October 2020 were screened, and randomly assigned to empagliflozin group (EG) or conventional group (CG) using a random number table. The enrolled patients were treated according to the guidelines, and patients in the empagliflozin group received additional empagliflozin (10 mg, once a day, orally) on top of the conventional treatment. The primary end points were VO₂peak at 6 months after treatment, and the secondary end points included other parameters of cardiopulmonary exercise test (CPET), 6-minute walking distance, N-terminal B-type pro-natriuretic peptide (NT-proBNP) level, and Kansas City Cardiomyopathy Questionnaire (KCCQ) score. Results: A total of 112 patients were included (mean age 69 (57, 78) years, 84 male (75.0%)). There were 55 cases in CG group and 57 cases in EG group. There were no significant differences in baseline data including age, sex, body mass index, left ventricular ejection fraction, systolic blood pressure, heart rate, estimated glomerular filtration rate, glycosylated hemoglobin, hemoglobin, NT-proBNP, daily dose of tolasemi, combined medication, CPET parameters, the proportion of New York Heart Association heart function Ⅲ/Ⅳ, history of coronary heart disease, history of hypertension, history of diabetes (all P>0.05). At 6 months after treatment, VO₂peak was significantly higher in EG group than in CG group(P=0.023). VE/VCO₂ slope was significantly lower in EG group than in CG group(P=0.034). Oxygen uptake efficiency slope was significantly higher in EG group than in CG group(P=0.038). The level of NT-proBNP was significantly lower in EG group than in CG group(P=0.020). Six-minute walking distance was significantly higher in EG group than in CG group(P=0.037). KCCQ score was significantly higher in EG group than in CG group(P=0.048). Exercise oscillatory ventilation decreased in both groups (1 case in each group, P>0.05). Conclusion: Empagliflozin can significantly improve VO₂peak in patients with HFmrEF.