Heart failure (HF) is a major healthcare problem. In patients with Heart Failure with Reduced Ejection Fraction (HFrEF), aldosterone antagonists reduce mortality and hospitalization rate. Gender-related differences have been described in the regulation of renin angiotensin aldosterone system (RAAS), which is at the core of the pathophysiology of HF. Regarding gender-related differences in the use of MRAs, less is known about the effects of androgens on RAAS.

In this single-center prospective cohort, a total of 100 adult (≥ 18 years) ambulatory patients of both sexes with the diagnosis of HF with HFrEF (LVEF≤ 40%) and NYHA class II-IV under optimized medical therapy started an aldosterone antagonist are enrolled and followed-up for 6 months. Patients are categorized according to their apparent sexual gender into two groups: the male group and the female group.

Inclusion Criteria:

• The diagnosis of heart failure with reduced ejection fraction HFrEF (LVEF≤ 40%) and New York Heart Association (NYHA) class II-IV under optimized medical therapy who are presented to the outpatient clinic and started an aldosterone antagonist at the time of enrollment.

Exclusion Criteria:

• Pregnancy or breast-feeding.
• Serum creatinine > 2.5 mg/dL (221 μmol/L) in males and > 2 mg/dL (177 μmol/L) in women (or estimated glomerular filtration rate eGFR ≤ 30 mL/minute/1.73 m2).
• Hyperkalemia (serum potassium level > 5 mEq/L).
• Renal transplant.
• Concomitant administration of strong CYP3A inhibitors.
• Concomitant administration of potassium supplements or potassium-sparing diuretics.
• Disorders of adrenal glands (Addison disease).
• Patients who used mineralocorticoid receptor antagonists in the last 2 weeks before enrollment.
• Patients with a history of mineralocorticoid receptor antagonists allergy or intolerance.

New York Heart Association (NYHA) class II-IV heart failure with reduced ejection fraction HFrEF patients (LVEF≤ 40%).