This clinical trial aims to compare the efficacy and safety of acetazolamide versus metolazone as adjunctive treatments to standard therapy in patients with acute decompensated heart failure (ADHF). ADHF is a life-threatening condition, and current treatments often involve loop diuretics to alleviate volume overload. This study will assess the added benefit of acetazolamide and metolazone in improving decongestion, reducing hospital stays, and preventing complications such as renal dysfunction or electrolyte imbalances. Participants will be randomized to receive either acetazolamide or metolazone in addition to standard diuretic therapy. The trial will evaluate primary outcomes including successful decongestion, in-hospital mortality, and length of hospital stay, with secondary outcomes focusing on renal function, electrolyte disturbances, and overall safety. The study is conducted at Bahawal Victoria Hospital, Bahawalpur, and aims to provide valuable insights into the management of ADHF, especially in the Pakistani population.

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.