Oral Iron Repletion Effects On Oxygen Uptake in Heart Failure

Inclusion Criteria:

Age >18 years
Previous clinical diagnosis of heart failure with current New York Heart Association (NYHA) Class II-IV symptoms LVEF≤0.40 within 2 years prior to consent, and ≥3 months after a major change in cardiac status (i.e. CABG or CRT).
Serum ferritin between 15-100 ng/ml or serum ferritin between 100-299 ng/ml with transferrin saturation <20%
Hemoglobin 9.0-13.5 g/dL (males), 9-13.5 (females) at time of enrollment

Stable evidence-based medical therapy for HF (including beta-blocker and ACE-inhibitor/ARB unless previously deemed intolerant, and diuretics as necessary) with
a. Changes in diuretic dose guided by a patient-directed flexible dosing program are considered stable medical therapy

Willingness to provide informed consent

Exclusion Criteria:

Presence of a neuromuscular, orthopedic or other non-cardiac condition that prevents the patient from exercise testing on a bicycle/treadmill ergometer and/or inability to achieve an RER ≥ 1.0 on screening/baseline CPET
Severe renal dysfunction (eGFR< 20 ml/min/1.73m2)
Severe liver disease (ALT or AST > 3x normal, alkaline phosphatase or bilirubin >2x normal)
Gastrointestinal conditions known to impair Fe absorption (i.e. inflammatory bowel disease)
Known active infection as defined by current use of oral or intravenous antimicrobial agents
Documented active gastrointestinal bleeding
Active malignancy other than non-melanoma skin cancers
Anemia with known cause other than Fe deficiency or chronic disease
Fe overload disorders (i.e. hemochromatosis or hemosiderosis)
History of erythropoietin, IV or oral Fe therapy, or blood transfusion in previous 3 months.
Current ventricular assist device
Anticipated cardiac transplantation within the next 4 months
Primary hypertrophic cardiomyopathy, infiltrative cardiomyopathy, acute myocarditis, constrictive pericarditis or tamponade
Previous adverse reaction to study drug or other oral Fe preparation
Known or anticipated pregnancy in the next 4 months