Iron homeostasis in heart transplant recipients randomized to ferric derisomaltose or placebo.

INTRODUCTION: The randomized IronIC trial evaluated the effect of intravenous ferric derisomaltose on physical capacity in iron-deficient, maintenance heart transplant (HTx) recipients. Iron deficiency was defined as in heart failure with high cut-points for ferritin to compensate for inflammation. However, intravenous iron did not improve physical capacity except in patients with ferritin <30 µg/L. We aimed to explore determinants of iron status in the 102 IronIC participants to better define iron deficiency in the HTx population. METHODS: We assessed key governors of iron homeostasis, such as hepcidin, soluble transferrin receptor (sTfR), and interleukin-6 (IL-6). We also measured growth factors and inflammatory markers with relevance for iron metabolism. The results were compared to those of 21 healthy controls. RESULTS: Hepcidin did not differ between HTx recipients and controls, even though markers of inflammation were modestly elevated. However, HTx recipients with ferritin <30 µg/L or sTfR above the reference range had significantly reduced hepcidin levels suggestive of true iron deficiency. In these patients, intravenous iron improved peak oxygen uptake. Hepcidin correlated positively with ferritin and negatively with sTfR. CONCLUSION: HTx recipients with iron deficiency as defined in heart failure do not have elevated hepcidin levels, although inflammatory markers are modestly increased. The high ferritin cut-offs used in heart failure may not be suitable to define iron deficiency in the HTx population. We suggest that hepcidin and sTfR should be measured to identify patients with true iron deficiency, who might benefit from treatment with intravenous iron.

Prevalence of iron deficiency in heart transplant recipients.

BACKGROUND: Optimal iron management is crucial to marginal patients such as heart transplant recipients. As inflammatory mechanisms are present in transplant recipients, the definition of iron deficiency used in the general population might not be appropriate. OBJECTIVE: To evaluate the prevalence and determinants of iron deficiency in Norwegian heart transplant recipients. METHODS: We consecutively assessed iron parameters in all Norwegian heart transplant recipients at their annual follow-up. Several definitions of iron deficiency suggested in the literature were assessed: ferritin <100 µg/L, or ferritin 100-300 µg/L combined with transferrin saturation of <20% (IDHF ); ferritin <100 µg/L (IDF100 ); transferrin saturation of <20% (IDTsat ), and ferritin <30 µg/L (IDF30 ). RESULTS: 179 of 378 heart transplant recipients (47%) had iron deficiency defined as IDHF . 152 patients (40%) had IDF100 , and 103 patients (27%) had IDTsat . 17 patients (5%) had IDF30 . 88 patients (23%) had a C-reactive protein (CRP) >5.0 µg/L. CONCLUSION: Iron deficiency defined as IDHF , IDF100, or IDTsat is prevalent in the heart transplant population, while IDF30 is not. Further research is required to identify the mechanisms of iron homeostasis in heart transplant recipients and to establish a definition of iron deficiency suitable for this population.

Intravenous iron supplement for iron deficiency in cardiac transplant recipients (IronIC): A randomized clinical trial.

AIMS: Heart transplant recipients have reduced exercise capacity despite preserved graft function. The IronIC trial was designed to test the hypothesis that intravenous iron therapy would improve peak oxygen consumption in these patients. METHODS AND RESULTS: This randomized, placebo-controlled, double-blind trial was performed at our national center for heart transplantation. One hundred and 2 heart transplant recipients with a serum ferritin <100 µg/liter or 100 to 300 µg/liter, in combination with transferrin saturation of <20%, and hemoglobin level >100 g/liter were enrolled ≥1 year after transplantation. A cardiopulmonary exercise test was performed before administration of the study drug and at 6 months follow-up. The primary endpoint was peak oxygen consumption. Key secondary outcomes included iron status, handgrip strength, quality of life, and safety. Fifty-two patients were randomized to receive ferric derisomaltose 20 mg/kg, and 50 to placebo. The between-group difference in baseline-adjusted peak oxygen consumption was 0.3 ml/kg/min (95% confidence interval -0.9 to 1.4, p = 0.66). In patients with a baseline ferritin <30 µg/liter, peak oxygen consumption was significantly higher in the ferric derisomaltose arm. At 6 months, iron stores were restored in 86% of the patients receiving ferric derisomaltose vs 20% in patients receiving placebo (p < 0.001). Quality of life was significantly better in patients receiving ferric derisomaltose. Twenty-seven adverse events occurred in the intravenous iron group vs 30 in the placebo group (p = 0.39). CONCLUSION: Intravenous iron treatment did not improve peak oxygen consumption in heart transplant recipients with ferritin <100 µg/liter or 100 to 300 µg/liter in combination with transferrin saturation <20%. TRIAL REGISTRATION NUMBER: http//www.clinicaltrials.gov identifier NCT03662789.