Based on ADVOR trial, the potential of adding acetazolamide in increasing the success of decongestion, the amount of natriuresis and diuresis. However, the use of intravenous acetazolamide may not be possible in Indonesia, where the intravenous formulation is not available. This clinical research study is being conducted in single hospitals in Indonesia. We aim to learn if Oral Acetazolamide in addition to Furosemide intravenous works to treat congestion in Acute Decompensated Heart Failure, besides evaluating the total urinary output, change of NT pro BNP level, and safety profile of oral Acetazolamide.

The hypothesis of this study is oral acetazolamide works well to achieve successful decongestion.

This is a randomized, double blind study with 2 treatment groups. Participants diagnosed with ADHF who meet the inclusion criteria and no exclusion criteria are given an explanation regarding the research and additional therapy that will be given, then informed consent is requested. Participants will be randomized to one of the two treatment groups by chance. Patients randomized to the first group will receive intravenous furosemide and oral acetazolamide. Patients randomized to the other treatment group will receive a combination of iv furosemide and placebo. It is expected that the patients of the treatment group with the combination therapy will have a faster reduction of their fluid overload. In consequence the treatment duration and total dose of diuretics administered will be shorter.

Inclusion Criteria:

• Agree to be included in the research by signing informed consent
• Patients with a clinical diagnosis of acute decompensated heart failure with at least one clinical sign of volume overload with a congestion score ≥2 (ADVOR Score) (e.g. edema (score 2 or more), ascites confirmed by physical examination or ultrasonography or pleural effusion confirmed by chest x-ray or echocardiography).
• Patients on routine oral loop diuretic therapy with a dose of ≥40 mg furosemide for ≥1 month
• Plasma NT-proBNP levels that increase ≥300 pg/mL or the applicable cut-off according to the age range at the time of examination in the ER.

Exclusion Criteria:

• Subjects with acute coronary syndrome
• History of congenital heart disease requiring surgical correction.
• Subjects in cardiogenic shock.
• Estimated glomerular filtration rate <20 mL/min/1.73m² at the time of examination.
• Use of renal replacement therapy or ultrafiltration at any time before the study was included.
• Treatment with acetazolamide within 1 month before randomization.
• Exposure to nephrotoxic agents (i.e. contrast dye) is anticipated within the next 3 days
• Subjects who are pregnant or breastfeeding.
• Subjects with urinary incontinence who are unwilling to use a bladder catheter.

Currently, the decision regarding which Individual Participant Data (IPD) will be included for sharing is still under consideration. This undecided status is due to several key factors that require thorough evaluation