Ferric Carboxymaltose Therapy Improves the Index of Cardiac Electrophysiological Balance in Iron-Deficient Heart Failure with Reduced Ejection Fraction.

Background and Objectives: Iron deficiency (ID) is common in heart failure with reduced ejection fraction (HFrEF) and is associated with adverse clinical outcomes. Although intravenous ferric carboxymaltose (FCM) improves functional status, its effects on ventricular electrophysiological indices remain incompletely characterized. This study evaluated short-term changes in the corrected index of cardiac electrophysiological balance (iCEBc) and conventional electrocardiographic repolarization parameters after FCM administration. Materials and Methods: This retrospective single-center pre-post study included 92 clinically stable patients with HFrEF and ID who received intravenous FCM. Standard 12-lead electrocardiograms and laboratory parameters were evaluated at baseline and 30 ± 5 days after treatment. The primary outcome was the within-patient change in iCEBc, while secondary outcomes included conventional ventricular repolarization indices. Results: Following FCM treatment, ferritin, transferrin saturation, and hemoglobin increased significantly (all p < 0.001). iCEBc decreased significantly (4.33 ± 1.04 vs. 4.04 ± 0.82, p = 0.016). Significant reductions were also observed in QTc, JTc, JT, Tp-e, Tp-e/QT, Tp-e/QTc, frontal QRS-T angle, and QT, whereas QRS duration remained unchanged. Changes in iron indices were not associated with changes in iCEBc. Conclusions: In this uncontrolled pre-post cohort, intravenous FCM was associated with favorable short-term changes in several electrocardiographic repolarization indices. However, because anemia correction occurred concurrently and no control group or clinical arrhythmic outcomes were available, these findings should be considered exploratory and hypothesis-generating rather than evidence of an antiarrhythmic effect.