Intravenous Iron Supplement for Iron Deficiency in Cardiac Transplant Recipients (IronIC) - A Randomized, Double Blind, Controlled Trial

Abstract

Heart transplant recipients have reduced exercise capacity despite preserved graft function. Numerous mechanisms may contribute to this impaired exercise tolerance, one of which may be iron deficiency (ID). Among our heart transplant survivors, 48 % have ID. The IronIC trial (NCT03662789) was designed to test the hypothesis that intravenous (i.v.) iron therapy will improve exercise capacity assessed by peak oxygen consumption. 102 stable, cardiac transplant recipients with ID, defined as serum ferritin <100 µg/l, or ferritin between 100 and 300 µg/l in combination with transferrin saturation <20 %, have been randomized in a 1:1 manner to treatment with intravenous iron isomaltoside, 20 mg/kg, or NaCl. Care was taken to blind patients and personnel to the color of the infusate. All participants provided written, informed consent. Exclusion criteria included hemoglobin <100 g/l, red blood cell disorders, end-stage kidney failure, intolerance to iron isomaltoside, and ongoing infections or rejections. Prior to the intervention, all patients underwent a treadmill test to measure peak oxygen consumption. Muscle strength by a hand grip test, cognitive function, and self-reported quality of life were also measured. All tests are repeated at follow-up 6 months after intervention. The trial is powered to detect a 1.5 ml/kg/min between-group difference in the change in peak oxygen consumption. Last patient is scheduled for follow-up February 2020. The primary objective is to assess baseline-adjusted peak oxygen consumption, six months after one single dose of iron isomaltoside. Secondary objectives are to assess the impact of treatment on iron stores, muscle strength, cognitive function, quality of life, safety and tolerability. This study will give insight to whether heart transplant recipients with ID can benefit from intravenous iron supplement. Results will be ready for presentation at the 2020 ISHLT conference.