Iron Deficiency in Pediatric Dilated Cardiomyopathy is Associated with Clinical, Biochemical and Hematological Markers of Severe Disease and Adverse Outcomes

Abstract

<h3>Purpose</h3> Adult studies suggest that iron deficiency (ID) is a common and treatable contributor to morbidity and mortality in heart failure. There is limited evidence as to the impact of ID in children and adolescents with dilated cardiomyopathy (DCM). <h3>Methods</h3> This was a retrospective single-centre review. All patients age < 18 years seen between 2010-2020 with a diagnosis of DCM and complete iron studies (ferritin, iron, transferrin and transferrin saturation) were included. Patients were excluded if they were on erythropoietin-stimulating agents, had received a transfusion in the preceding fortnight, or were post-heart transplant (HTx). ID was defined as ≥ 2 of ferritin < 15 μg/L, iron < 9 μmol/L, transferrin > 3 g/L or transferrin saturation < 15%. Clinical, biochemical and haematological indices, and the incidence of a composite adverse event (CAE) of mechanical circulatory support (MCS), HTx or death at 3 and 6 months were compared between children with ID and without. <h3>Results</h3> Of 138 patients with DCM, 49 patients had iron studies results available and were included. The mean (SD) age at time of iron studies was 5.8±5.2 years old, and 26 (53%) were female. Twenty-nine (59%) had ID and 29 (59%) were anemic; of these, 22 (45%) were both iron deficient and anemic. Eleven (22%) had renal impairment and 16 (32%) had biochemical liver dysfunction. Children with ID had a higher incidence of anemia (22, 76%, <i>P</i> = 0.004), microcytosis (9, 31%, <i>P</i> = 0.034), hypochromia (16, 55%, <i>P</i> = 0.005), a higher median NT-BNP (1590 pg/ml, IQR 456 - 3446, <i>P</i> = 0.001), and a lower median albumin (37 g/L, IQR 33 - 41, <i>P</i> = 0.008). Children with ID were more likely to be receiving inotropes (17, 59%, <i>P</i> = 0.002) and invasive/non-invasive ventilation (13, 45%, <i>P</i> = 0.009) than those who were iron replete. The CAE occurred in 8 children (28%; 4 MCS, 2 HTx, 2 deaths) with ID by 3 months (<i>P</i> = 0.015). By 6 months, it had occurred in 10 (34%; 1 MCS, 1 death) children with ID, and 2 (20%; 1 MCS, 1 death) children who were iron replete (<i>P</i> = 0.09). <h3>Conclusion</h3> ID occurred in more than half of our patient population with DCM who have had iron studies measured. ID is associated with severe clinical, haematological and biochemical disease and an increased composite risk of MCS, HTx or death. The need for iron replacement therapy should be considered in all patients who present with heart failure related to DCM.