Diuretic and Natriuretic Effect of High-dose Spironolactone in Patients With Acute Heart Failure

Inclusion Criteria: * Diagnosis of acute heart failure within the past 8 hours * Two of the following: 1. edema, 2. ascites, 3. jugular vein distention, 4. pulmonary congestion * NT-proBNP \>1,000 pg/ml or \>3,000 pg/ml (in the presence of atrial fibrillation) * Per os mean daily loop diuretic dose equivalent to 80 mg of furosemide for at least 1 month prior to presentation and at least one of the following: 1. serum urea/serum creatinine \> 50 at presentation, 2. serum creatinine increased \>0.3 mg/dl compared with previous value (within the last year), 3. serum creatinine \> 1.8 mg/dl. Exclusion Criteria: * pregnancy or breast feeding * current acute coronary syndrome * significant valvular disease * pulmonary embolism * allergy or intolerance to spironolactone * current mechanical circulatory support * primary hypertrophic cardiomyopathy, infiltrative cardiomyopathy * mean arterial pressure \<65mmHg or systolic arterial pressure \<90 mmHg at presentation * anticipated use of inotropes or vasodilators (other than renal doses of dopamine, i.e. \<2.5 μg/kg/min) * anticipated need of ultrafiltration * exposure to nephrotoxic agents within 3 days of presentation * serum potassium\> 5 mmol/L * per os receipt of spironolactone or eplerenone in a dose \> 50 mg daily prior to presentation.