Comparative Efficacy and Safety of Acetazolamide Versus Metolazone as an Adjunct to Standard Therapy in Patients With Acute Decompensated Heart Failure

Inclusion Criteria: * Aged 18 years or older. * Diagnosed with Acute Decompensated Heart Failure (ADHF), with either preserved or reduced ejection fraction (EF). * At least one clinical sign of volume overload, such as: * Pleural effusion (confirmed by chest X-ray or ultrasound). * Oedema or ascites (verified by abdominal ultrasonography). * Plasma NT-proBNP level \> 1000 pg/mL or BNP level \> 250 ng/mL at screening. * Receiving at least 40 mg of furosemide as oral maintenance therapy for at least one month prior to the study initiation. Exclusion Criteria: * Previous use of acetazolamide or metolazone prior to the study period. * Known hypersensitivity or allergies to the study drugs (acetazolamide or metolazone) or their components. * Patients with electrolyte disturbances, especially hypokalemia. * End-stage renal disease requiring dialysis or GFR \< 20 mL/min/1.73 m². * Pregnant or breastfeeding women. * Severe hypotension (systolic blood pressure \< 90 mmHg) or other significant comorbidities like congenital cardiac illness requiring surgery. * Patients requiring renal replacement therapy during the hospitalization. * History of significant electrolyte imbalances or acid-base disturbances.