Mineralocorticoid receptor antagonists (MRAs) improve outcomes in patients with chronic heart failure (CHF) caused by LV systolic dysfunction (LVSD).1–3 Eplerenone and spironolactone (or its metabolite, potassium canrenoate) are the currently licensed MRAs for clinical use. Clinical studies show the benefit of MRAs, but there are limited data on direct comparison of these MRAs. It is generally believed that the benefits of different MRAs represent a ‘class effect’.