The goal of this phase IV, open-label, randomized clinical trial is to evaluate whether intravenous iron improves quality of life in adults aged 65 years and older with iron deficiency after an acute coronary syndrome (ACS).

The main questions it aims to answer are:

• Does intravenous iron improve quality of life at 6 and 12 months?
• Does it reduce frailty and adverse clinical outcomes?

Researchers will compare intravenous ferric carboxymaltose with standard of care.

Participants will:

• Be randomly assigned to receive intravenous iron or standard care
• Attend three study visits over 12 months
• Complete questionnaires and undergo blood tests

Acute coronary syndrome (ACS) remains one of the leading causes of morbidity and mortality in adults aged 65 years and older. Iron deficiency is a frequent condition in this population following an ACS event and has been associated with impaired functional capacity, increased frailty, worse quality of life, and poorer clinical outcomes. While intravenous iron supplementation has demonstrated clinical benefits in patients with heart failure, its role in older patients with iron deficiency after ACS has not been systematically evaluated.

This phase IV, multicenter, open-label, randomized clinical trial has been designed to assess the impact of intravenous iron administration on quality of life and clinical outcomes in older patients with iron deficiency following ACS. The study will include patients aged 65 years or older diagnosed with ACS within the previous 15 days and presenting with iron deficiency according to current European Society of Cardiology criteria.

Eligible participants will be randomized in a 1:1 ratio to receive either a single intravenous dose of ferric carboxymaltose, administered according to body weight and baseline hemoglobin levels, or standard of care without intravenous iron supplementation. Randomization will be centralized and stratified by participating center. Given the nature of the intervention, the study will be conducted in an open-label fashion.

Participants will be followed for 12 months after randomization, with study visits scheduled at baseline, 6 months, and 12 months. Throughout follow-up, comprehensive clinical assessments will be performed, including evaluation of quality of life using the EQ-5D-5L questionnaire and assessment of frailty using the FRAIL scale. Clinical events such as heart failure decompensation, recurrent myocardial infarction, stroke, and all-cause mortality will be systematically recorded.

In addition, serial blood samples will be collected to analyze iron metabolism parameters and inflammatory biomarkers. Exploratory analyses will focus on the assessment of biological aging and cardiovascular risk markers, including DNA methylation of the ELOVL2 gene, telomere length, and circulating levels of Klotho and fibroblast growth factor 23 (FGF23). These analyses aim to provide mechanistic insights into the potential effects of iron repletion on biological aging and cardiovascular risk in this vulnerable population.

The overall duration of the study is two years, including a one-year recruitment period and a one-year follow-up period. The trial is sponsored by INCLIVA - Health Research Institute and conducted across multiple centers in Spain. The results of this study are expected to provide robust clinical evidence to support optimized management of iron deficiency in older patients following ACS, with the potential to inform future clinical guidelines and improve patient-centered outcomes.

Inclusion Criteria:

1. Age ≥ 65 years.

2. Hospitalization for confirmed acute coronary syndrome (ACS) within 15 days prior to enrollment.

3. Iron deficiency diagnosed at admission or within 15 days after the index ACS event, defined as:

   • Serum ferritin < 100 ng/mL, OR
   • Transferrin saturation (TSAT) < 20%.

4. Ability to provide written informed consent prior to participation.

Exclusion Criteria:

1. Active malignancy.
2. End-stage or terminal illness as determined by the IDC-Pal score.
3. Known heart failure with left ventricular ejection fraction (LVEF) < 40% prior to enrollment, or development of LVEF < 40% during hospitalization or within 15 days after ACS.
4. Chronic dialysis or advanced renal or hepatic failure.
5. Severe anemia (hemoglobin < 10 g/dL) at the time of ACS or within 15 days after the event.
6. Prior treatment with intravenous or oral iron within 12 months before the index ACS.
7. Known hypersensitivity to ferric carboxymaltose, other parenteral iron products, or any component of the formulation.
8. Evidence of iron overload or disorders of iron metabolism.
9. Ongoing bacteremia or active systemic infection.
10. Participation in another interventional clinical trial involving an investigational medicinal product.
11. Any condition that, in the investigator's opinion, would compromise safety, protocol compliance, or study integrity.