Cognitive Function Among Heart Transplant Recipients Before and After Intravenous Iron Supplement for Iron Deficiency: Results From a Randomized, Placebo-Controlled, Double-Blind Treatment Trial.

Abstract

BACKGROUND: Cognitive dysfunction after successful heart transplantation (HTx) is not uncommon. Lower hemoglobin levels have previously been associated with cognitive dysfunction in heart transplant recipients (HTx recipients). In a randomized, placebo-controlled, double-blind treatment trial, we assessed as a pre-specified secondary outcome whether a single intravenous iron supplement for iron deficiency in HTx recipients resulted in changes in cognitive function after 6 months. METHODS: In the "Intravenous Iron Supplement for Iron Deficiency in Cardiac Transplant Recipients" (IronIC) trial, we assessed cognitive function at baseline and at 6-month follow-up with the following tests of the Cambridge Neuropsychological Test Automated Battery: Reaction Time, Paired Associates Learning, and Spatial Working Memory. Of 94 participants with cognitive data at baseline and follow-up, 49 were randomized to the single intravenous iron supplement, while 45 received placebo. RESULTS: Raw score changes from baseline to follow-up did not differ statistically significantly between study groups (two measures of each test analyzed). In the total sample, 27%-44% of participants performed at baseline at least one standard deviation below the normative mean on measures of memory and working memory/executive functions. Exploratory analyses indicated that performance on measures of memory might decrease more than expected with increasing age. CONCLUSION: A single intravenous iron supplement for iron deficiency in HTx recipients did not result in statistically significant cognitive changes after 6 months. The group as a whole performed approximately half a standard deviation below the normative mean on measures of memory and working memory/executive functions. Regular cognitive screening after HTx is recommended. CLINICAL TRIAL REGISTRATION: Trial Registration: ClinicalTrials.gov identifier: NCT03662789.