Inclusion Criteria:

• 18 years of age or older;
• Outpatients followed at a HF Clinic in a tertiary care Hospital with clinical diagnosis of HF for at least 3 months before study entry;
• NYHA functional class II to IV, who are able to perform ergospirometry;
• Documentation of LVEF < 40% within the last 6 months;
• Adequate baseline therapy for HF based on patient’s functional class (β-blockers, ACE inhibitors irrespective of functional class except if contra-indications, digoxin, spironolactone if NYHA class III or IV);
• Stable baseline HF therapy with same doses of medications and no intent to increase doses for the following 3 months;
• Hemoglobin ≤ 12 g/dl and > 9 g/dl;
• Transferrin saturation < 20% and ferritin < 500 µg/L;
• Ability to provide written informed consent.

Exclusion Criteria:

• Any clinically overt bleeding: gastrointestinal bleeding, hypermenorrhea, history of peptic ulcer without evidence of healing or inflammatory intestinal diseases;
• Uncorrected hypothyroidism;
• Other inflammatory, neoplastic or infectious disease;
• Serum creatinine > 1,5 mg/dl;
• Previous intolerance to oral elemental iron compounds;
• HF due to alcoholic cardiomyopathy, current regular drinker of alcoholic beverages or HF due to peripartum cardiomyopathy;
• Recent admission for decompensated HF (last month)
• Recent myocardial revascularization procedures (last 3 months);
• Recent ACS, stroke or TIA (last 3 months);
• Active or metastatic neoplastic disease with life expectancy of less than a year;
• Patients in heart transplantation list;
• Patients that had participated in any other clinical trial or study within the last month;
• Pregnant or lactating women;
• Pre-menopausal women that are not using any effective method of contraception;
• Patients using prohibited medications or that have not yet accomplished the wash-out period;
• Patients currently participating in cardiovascular rehabilitation programs.