Can stents cause iron deficiency anemia?

Can Stents Cause Iron Deficiency Anemia?

Coronary stents themselves do not directly cause iron deficiency anemia, but the antiplatelet therapy required after stent placement is a significant risk factor for developing iron deficiency anemia due to occult gastrointestinal blood loss.

Mechanism of Iron Deficiency Anemia in Patients with Stents

Antiplatelet Therapy as the Primary Cause

• Patients with coronary stents require dual antiplatelet therapy (DAPT), typically consisting of aspirin plus a P2Y12 inhibitor such as clopidogrel, for varying durations after stent placement 1
• This antiplatelet therapy, particularly when used long-term, can cause chronic occult gastrointestinal blood loss leading to iron deficiency anemia
• Low-dose aspirin (75-100 mg/day) has been associated with iron deficiency anemia in approximately 20% of otherwise healthy elderly individuals, even in the absence of major gastric bleeding 2

Additional Contributing Factors

• Aspirin metabolites (salicyluric acid, salicylic acid, 2,5-dihydroxybenzoic acid, and 2,3-dihydroxybenzoic acid) have iron-chelating properties that may increase iron excretion 2
• The risk of bleeding is significantly higher with the combination of oral anticoagulants plus antiplatelet therapy 1
• Patients with cardiovascular disease often have other risk factors for iron deficiency, including:
  • Advanced age
  • Chronic kidney disease
  • Heart failure
  • Chronic inflammation associated with atherosclerosis (increasing hepcidin and reducing iron absorption)
  • Reduced gastric acidity 3

Clinical Significance

Impact on Cardiovascular Outcomes

• Iron deficiency anemia is a strong predictor of cardiac mortality in patients with reduced ejection fraction undergoing coronary stenting 4
• In a study of patients with left ventricular systolic dysfunction (EF ≤45%) undergoing coronary stenting, those with iron deficiency anemia had significantly higher cardiac mortality (33%) compared to non-anemic patients (1%) 4

Risk Factors for Increased Bleeding with Antiplatelet Therapy

The following factors increase bleeding risk in patients on DAPT 1:

• History of prior bleeding
• Oral anticoagulant therapy
• Female sex
• Advanced age
• Low body weight
• Chronic kidney disease
• Diabetes mellitus
• Anemia
• Chronic steroid or NSAID therapy

Diagnosis of Iron Deficiency Anemia

When suspecting iron deficiency anemia in patients with stents:

1. Laboratory evaluation should include:

   • Complete blood count with hemoglobin, red cell indices
   • Absolute reticulocyte count
   • Serum ferritin level (most powerful test for iron deficiency)
   • Transferrin saturation (TSAT)
   • Serum vitamin B12 and folate levels 1, 5

2. Diagnostic criteria:

   • Serum ferritin <12-15 μg/dL is diagnostic of iron deficiency
   • In patients with inflammation, malignancy, or hepatic disease, ferritin may be falsely elevated but iron deficiency is unlikely if ferritin >100 μg/dL
   • Transferrin saturation <30% helps confirm the diagnosis 1, 5

Management Approach

Gastrointestinal Evaluation

• All patients with confirmed iron deficiency anemia should undergo gastrointestinal evaluation unless there is a clear non-GI source of blood loss 1
• Upper GI endoscopy should be performed first, with small bowel biopsies to rule out celiac disease (present in 2-3% of IDA cases)
• Lower GI examination (colonoscopy) should follow unless carcinoma or celiac disease is found in the upper GI tract
• Dual pathology (lesions in both upper and lower GI tract) occurs in 10-15% of cases 1, 5

Iron Replacement Therapy

• Oral iron is the first-line therapy for most patients
• Continue for 3 months after normalization of hemoglobin to replenish iron stores
• Intravenous iron may be indicated for patients with:
  • Intolerance to oral iron
  • Poor absorption
  • Chronic inflammatory conditions
  • Ongoing blood loss 5

Antiplatelet Management

• Do not discontinue antiplatelet therapy without careful consideration of thrombotic risk
• For patients at high bleeding risk but requiring continued antiplatelet therapy:
  • Consider dropping aspirin while continuing P2Y12 inhibitor in selected cases
  • Avoid switching to more potent P2Y12 inhibitors (prasugrel or ticagrelor) due to increased bleeding risk 1

Monitoring and Follow-up

• Monitor hemoglobin and red cell indices at regular intervals
• Check hemoglobin weekly until stable, then every 2-4 weeks
• Monitor ferritin and transferrin saturation monthly during initial treatment
• Consider repeat endoscopic procedures if iron deficiency anemia recurs 5

Common Pitfalls to Avoid

• Failing to investigate for gastrointestinal causes of iron deficiency anemia in patients with stents
• Prematurely discontinuing antiplatelet therapy without considering thrombotic risk
• Misinterpreting ferritin levels in the presence of inflammation
• Inadequate duration of iron therapy
• Deferring iron replacement while awaiting investigations 5

Iron deficiency anemia in patients with coronary stents requires a balanced approach that addresses both the anemia and maintains appropriate antiplatelet therapy to prevent stent thrombosis.