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.
Keywords: cardiac transplant; health-related quality of life; heart transplant; iron deficiency; peak oxygen consumption.
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