Iron Deficiency in Adults with Complex and/or Cyanotic Congenital Heart Disease—How to Diagnose and Whom to Treat?

Background: Iron deficiency (ID) is common in adult congenital heart disease (ACHD). Yet, specific diagnostic and therapy guidelines tailored to this population are lacking. In cyanotic CHD secondary erythrocytosis, often “normal” ferritin levels and red blood cell indices mask ID, hindering the establishment of ID diagnosis and appropriate treatment. Iron supplementation is a cornerstone of heart failure therapy. However, even in acquired heart disease, diagnostic ID criteria of the current ESC and AHA heart failure guidelines remain under discussion, with a transferrin saturation (TSAT)-centered approach recently suggested. This study aimed to assess various ID diagnostic criteria in a cohort of patients with complex and/or cyanotic CHD.

Methods: In this cross-sectional clinical study, clinical and laboratory data were collected from 326 patients (56% female; mean age 37.2 ± 13.3 years) with complex and/or cyanotic CHD. Incorporating clinical and laboratory data, different ID definitions were evaluated: (1) Absolute ID (Ferritin <20 μg/L) versus (2) ESC heart failure (ESC-HF) guideline (Ferritin <100 μg/L, irrespective of TSAT; or Ferritin 100–299 μg/L if TSAT <20%) versus (3) TSAT (<20%) definition. Group differences were assessed using Student’s t-test.

Results: Among this cohort, 65% (212/326) of patients were cyanotic (SpO₂ ≤90%). Applying the different diagnostic criteria, the prevalence of ID in noncyanotic/cyanotic patients was 15%/21% using (1) absolute ID criteria, 69%/71% using the (2) ESC-HF definition, and 56%/52% using the (3) TSAT definition, respectively. Hemoglobin levels and red blood cell indices were significantly lower across all ID diagnostic criteria (all p < 0.05). Oxygen saturation as a possible confounder did not differ between subgroups. Noteworthy, applying the TSAT criteria in cyanotic patients, NT-proBNP was remarkably higher (p = 0.004) if ID was present, and 62% of ID patients were functional class ≥3.

Conclusion: ID is highly prevalent in adults with complex and/or cyanotic CHD when applying standard diagnostic criteria derived from heart failure guidelines. This study underscores the clinical relevance of addressing iron metabolism in CHD and highlights the urgent need for further research to refine diagnostic and therapeutic strategies. Regarding iron deficiency in CHD, it is time to clarify: How to diagnose and whom to treat?

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Artikel online veröffentlicht:
11. Februar 2025