Acetazolamide versus metolazone added to usual diuretics for acute decompensated heart failure

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

This trial will test whether adding acetazolamide or metolazone to standard diuretics works better and is safer for adults hospitalized with acute decompensated heart failure.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 320 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: University of Health Sciences Lahore (Academic / other)
• Locations: 1 site (Chak Four Hundred Fifty-four, Punjab Province)
• Trial ID: NCT07199088 on ClinicalTrials.gov

What this trial studies

This randomized interventional trial will assign adults hospitalized with acute decompensated heart failure to receive either acetazolamide or metolazone in addition to their standard loop diuretic therapy. The study will measure successful decongestion, in-hospital mortality, and length of hospital stay as primary outcomes, with secondary monitoring of kidney function, electrolyte changes, and overall safety. Participants must have clinical signs of volume overload and elevated natriuretic peptides, and those with end-stage renal disease, severe hypotension, recent use of the study drugs, or pregnancy are excluded. The trial is being conducted at a single center in Bahawalpur, Pakistan, and aims to inform optimal adjunctive diuretic choice in this high-risk population.

Who should consider this trial

Good fit: Adults aged 18 or older hospitalized with acute decompensated heart failure (reduced or preserved EF), with at least one sign of volume overload and elevated NT-proBNP/BNP who have been on at least 40 mg oral furosemide daily for one month are ideal candidates.

Not a fit: Patients on dialysis, with GFR <20 mL/min/1.73 m², severe hypotension, significant electrolyte disturbances, known allergy to the study drugs, or who are pregnant or breastfeeding are excluded and unlikely to benefit from participation.

Why it matters

Potential benefit: If successful, the results could help clinicians choose an adjunct diuretic that improves decongestion, shortens hospital stays, and reduces complications like kidney problems or electrolyte imbalances.

How similar studies have performed: Recent trials and clinical experience have shown benefit for acetazolamide in improving decongestion and for metolazone as a useful adjunct in diuretic resistance, but direct head-to-head comparisons remain limited.

Eligibility criteria

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.

Where this trial is running

Chak Four Hundred Fifty-four, Punjab Province

• Quaid e Azam Medical College , bahawalpur — Chak Four Hundred Fifty-four, Punjab Province, Pakistan (Recruiting)

Study contacts

• Study coordinator: Matiullah Azmoon

Conditions Acute Decompensated Heart Failure; Heart Failure, Diastolic; Heart Failure, Systolic