IRONICA: IRON Repletion In Heart Failure - A Comparison of Oral and IV Approaches

Inclusion Criteria: * Age ≥18 years * BMI ≥18.0 kg/m² * Hemoglobin: \> 9 g/dL and \<14 g/dL for men \> 9 g/dL and \<13 g/dL for women * Diagnosed with Congestive Heart failure: HFrEF: EF ≤40% in any recent echocardiogram HFpEF: EF ≥50-55% without any prior EF ≤40%, and evidence of diastolic dysfunction per ASE/EACVI 2023 criteria-defined as either grade ≥2 or ≥2 supporting echo parameters (septal e' \<7 cm/sec or lateral e' \<10 cm/sec, E/e' ≥15, TR velocity \>2.8 m/s, LA volume index ≥34 mL/m², LV septal or posterior wall thickness ≥1.2 cm, or LA area ≥20 cm² / diameter ≥3.8 cm. * Documented elevated NT-proBNP based on BMI and rhythm: BMI \<35: ≥220 pg/mL (NSR) or ≥660 pg/mL (A-Fib) BMI ≥35: ≥125 pg/mL (NSR) or ≥375 pg/mL (A-Fib) * NYHA Class II-IV * Transferrin saturation (TSAT) \<20% * Hemoglobin \<14 g/dL for men, \< 13 g/dL for women. * Stable on heart failure therapy for ≥2-4 weeks * Currently prescribed a diuretic at home * Ambulatory (able to walk \>20 ft with minimal assistance) * Willing and able to give informed consent Exclusion Criteria: * Received IV iron, ESA, or blood transfusion within the last 6-12 months * Received high-dose oral iron (\>100 mg/day in past 7 days) * Severe renal impairment (eGFR \<15 mL/min/1.73 m² or on dialysis) * Patients with known cirrhosis or transaminitis with AST \>141 or ALT \>112 IU/L * Active bleeding or known bleeding disorder * Recent cardiac surgery, myocardial infarction, or stroke within past 3 months * Active infection, defined as any systemic or deep-seated infection (e.g., bacteremia, sepsis, osteomyelitis, or infections requiring IV antibiotics or hospitalization) at the time of screening. * Active malignancy or undergoing chemotherapy/radiotherapy * Vitamin B12 or folate deficiency (unless corrected prior to enrollment) * Chronic liver disease (with LFTs \>3× upper limit of normal) * Pregnant or breastfeeding women or those not using effective contraception * Lacks capacity to consent or unable to comply with study procedures