The impact of intravenous ferric carboxymaltose on reverse electrical remodeling following cardiac resynchronization therapy
Authors: Bozcali E , Polat V 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
The effect of intravenous ferric carboxymaltose (FCM) on reverse electrical remodeling (RER) in patients with heart failure with reduced ejection fraction (HFrEF) following cardiac resynchronization therapy (CRT) implantation is unknown.

Purpose
The current study aims to examine the effect of iron replacement with intravenous FCM on RER in CRT-implanted patients with HFrEF and iron deficiency.

Methods
The present study retrospectively analyzed 65 patients with successful CRT-D device implantation between March 2017 and January 2020 with iron deficiency (defined as ferritin &lt;100 μg/L) at implantation. Follow-up data were obtained from the 6-month routine follow-up visits of patients following CRT implantation. Demographic characteristics, laboratory results, medical history, medication details, functional status, information on whether intravenous FCM therapy was administered during CRT device implantation, echocardiographic left ventricular (LV) measurements, baseline electrocardiogram (ECG) recorded before CRT device implantation, and follow-up ECG were collected for analysis for each study patient. From baseline to 6-month follow-up, the change in intrinsic QRS duration (without biventricular pacing) was calculated as a primary endpoint, and the change in LV ejection fraction (LVEF) was assessed as a secondary endpoint of the study.

Results
Thirty-five of 65 patients were in the FCM group, while the remaining 30 study participants were in the non-FCM. The two study groups were similar regarding baseline characteristics, except for ferritin levels, which were minimally significantly lower in the FCM group (10.7±5.0μg/L vs 13.5 ±3.9μg/L, p= 0.012). At the 6-month follow-up, both mean ferritin levels increased significantly in the FCM group compared to baseline (from 10.7±5.0 to 86.5±7.6μg/L, p &lt; 0.0001), while these levels were not significantly increased in the non-FCM group (from 13.5±3.9 to 14.1±4.2μg/L, p = 0.962). There was a significant reduction in intrinsic QRS durations compared to baseline at 6-month follow-up after CRT implantation in both FCM and non-FCM group (from 148.4±5.3 to 138.0±5.1ms, p &lt; 0.0001; from 149.8±5.0 to 146.8±4.6ms, p &lt; 0.0001, respectively). The change in intrinsic QRS duration from baseline to 6-month follow-up was significantly greater in the FCM group than in the non-FCM group (-10.4±2.2ms vs -3±2.9ms, p &lt; 0.0001). At the 6-month follow-up, the change in LVEF from baseline was significantly higher in the FCM group than in the non-FCM group (+3.6±1.6% vs -0.1±1.7%, p &lt; 0.0001). The change in ferritin level was negatively correlated with the change in intrinsic QRS duration (r = -0.725, p &lt; 0.0001), whereas there was a positive correlation between the change in ferritin level and the change in LVEF (r = 0.712, p &lt; 0.0001).

Conclusions
Treatment with FCM was induced RER and improvement in LVEF in HFrEF patients with iron deficiency following CRT implantation.