Inclusion Criteria:

• Patients (age ≥ 18 years) with acute decompensated heart failure (HF) according to clinical assessment on active therapy with a SGLT2 inhibitor
• Brain Natriuretic Peptide (BNP) >100 pg/ml or N-terminal pro-BNP (NTproBNP) >300 pg/ml
• Written informed consent obtained
• Women of childbearing potential: negative pregnancy test and use of a highly effective method of contraception

Exclusion Criteria:

• Type 1 diabetes mellitus
• Chronic Kidney Disease (CKD) with eGFR<20 ml/min, or end-stage renal failure with the need for chronic dialysis treatment
• Acute kidney injury (AKI) requiring dialysis treatment
• Known intolerance to empagliflozin
• Acute heart failure without signs of congestion ("dry" patient)
• Indication for coronary angiography or any foreseeable administration of a contrast media
• Need for hemofiltration or any other form of extracorporeal therapy
• Planned surgery
• Previous participation in this trial or recent participation in another clinical trial (within the last 4 weeks before inclusion)
• Identification of any causes of heart failure leading to decompensation that needs urgent management (like acute coronary syndrome, severe unstable arrhythmias, mechanical causes, acute pulmonary embolism)
• Incapacity to understand and / or to provide written informed consent
• Obvious uncontrolled substance abuse
• Pregnancy, breastfeeding