Inclusion Criteria:

• Adult (≥ 18 years of age) able to provide signed, written informed consent.
• Stable heart failure (NYHA II-IV) on maximally-tolerated background therapy (as determined by the site Principle Investigator) for at least 2 weeks prior to randomization.
• Able and willing to perform a 6MWT at the time of randomization.
• Reduced left ventricular ejection fraction. Assessment must be performed at least 12 weeks after major cardiac surgical intervention including coronary artery bypass graft (CABG), valvular repair/replacement, or cardiac resynchronization therapy (CRT) device implantation.
• Left ventricular ejection fraction ≤ 40% obtained during the screening visit OR either of the following:
  • Historical value of ejection fraction ≤ 30% within 36 months of screening visit;
  • Historical value of ejection fraction ≤ 40% within 24 months of screening visit;
  • Hemoglobin > 9.0 g/dL and < 13.5 g/dL (females) or <15.0 g/dL (males) within 28 days of randomization;
  • Serum ferritin < 100 ng/mL or 100 to 300 ng/mL with TSAT < 20%. Patients with screening ferritin < 15 ng/mL must have documentation of an appropriate evaluation, as determined by the Principle Investigator, within 3 months of screening and prior to randomization.
• Either documented hospitalization for heart failure within 12 months of enrollment or elevated N-terminal-pro-brain natriuretic peptide (NT-proBNP) within 90 days of randomization:
  • For patients in normal sinus rhythm: N-terminal-pro-brain natriuretic peptide (NT-proBNP) > 600 pg/mL (or BNP > 200 pg/mL);
  • For patients in atrial fibrillation: NT-proBNP > 1000 pg/mL (or BNP > 400 pg/mL.

  • NOTE: NT-proBNP must be used to confirm eligibility for patients taking sacubitril/valsartan.

Exclusion Criteria:

• Known hypersensitivity reaction to any component of FCM.
• History of acquired iron overload, or the recent receipt (within 3 months) of erythropoietin stimulating agent, IV iron therapy, or blood transfusion.
• Acute myocardial infarction, acute coronary syndrome, transient ischemic attack, or stroke within 30 days of enrollment.
• Uncorrected severe aortic stenosis, severe valvular regurgitation (except mitral regurgitation due to left ventricular dilatation without planned intervention), or left ventricular outflow obstruction requiring intervention.
• Current atrial fibrillation or atrial flutter with a mean ventricular response rate > 100 per minute (at rest).
• Current or planned mechanical circulatory support or heart transplantation.
• Hemodialysis or peritoneal dialysis (current or planned within the next 6 months).
• Documented liver disease, or active hepatitis (i.e. alanine transaminase or aspartate transaminase > 3 times the upper limit of normal range).
• Current or recent (within 3 years) malignancy with exception of basal cell carcinoma or squamous cell carcinoma of the skin, or cervical intraepithelial neoplasia.
• Active gastrointestinal bleeding.
• Female participant of child-bearing potential who is pregnant, lactating, or not willing to use adequate contraceptive precautions during the study and for up to 5 days after the last scheduled dose of study medication.
• Inability to return for follow up visits within the necessary windows.
• Concurrently in a study with investigational product.
• Current COVID-19 infection.