Mineralocorticoid receptor antagonist (MRA) therapy is recommended in stable chronic systolic heart failure (HF) and post-infarction HF patients for improving morbidity and mortality. MRA therapy in AHF and in high doses is less well studied. The effectiveness and safety of early high dose MRA therapy in AHF is supported by a single-blind study showing lower risk of worsening renal function and need for loop diuretics, and improved congestion. MRA therapy in AHF may improve outcomes by relieving congestion at higher doses through their natriuretic property, in addition to preventing the deleterious effects of exacerbation of neuro-hormonal activation by loop diuretics.