Abstract Background Dapagliflozin (DAPA), a sodium-glucose co-transporter 2 inhibitor, has shown to reduce cardiovascular mortality in patients with chronic heart failure.1) In addition, DAPA can enhance diuresis in patients with acute decompensated heart failure (ADHF).2) However, there is little known how early initiation of DAPA might impact the worsening renal function (WRF) when combined with standard decongestive therapy for ADHF. Purpose We aimed to evaluate the impact of initiating DAPA within 24 hours after ADHF admission on WRF, compared to standard decongestive therapy with loop diuretics alone. Methods We enrolled consecutive ADHF patients with a left ventricular ejection fraction (LVEF) less than 50%. The patients were prospectively randomized to either the DAPA group who received DAPA at a dose of 10 mg once daily within 24 hours of admission or the conventional therapy group (CON group) who received loop diuretics alone. Furosemide, loop diuretic, dosage was adjusted by increase or decrease of 10 mg to maintain urine output between a 1-2 mL/kg/hour.3) The primary endpoint was the incidence of WRF, which was defined as an increase in the serum creatinine of ≥ 0.3 mg/dL from baseline within 7 days of admission.4) Additionally, right heart catheterization (RHC) was performed before discharge if the consent was obtained. Results From May 2021 to May 2023, we analyzed a total of 114 patients (56 in the DAPA group and 58 in the CON group). The mean age was 73 years, 35% were female, and the mean LVEF was 32.5%. There was no significant difference in the incidence of WRF between two groups (16.1% in the DAPA group vs. 12.1% in the CON group, P=0.54, Figure 1). The cumulative loop diuretics dose over 7 days was lower in the DAPA group than CON group (184 ± 9.64 mg vs. 214 ± 9.81 mg, P=0.03, Figure 2). RHC before discharge was performed in 54 patients (96.4%) in the DAPA group and in 54 (93.1%) in the CON group. There were no significant differences in the pulmonary artery wedge pressure, pulmonary artery pressure, right atrial pressure, and cardiac index by the thermodilution method or the Fick method between two groups. Conclusion This randomized prospective trial revealed the early initiation of DAPA within 24 hours of admission for ADHF reduced loop diuretic demand without inducing WRF compared to standard decongestive therapy.Figure 1Figure 2