BACKGROUND Left ventricular (LV) remodeling and diastolic function in people with heart failure (HF) are correlated with iron status; however, the causality is uncertain. This Mendelian randomization (MR) study investigated the bidirectional causal relationship between systemic iron parameters and LV structure and function in a preserved ejection fraction population.
METHODSTransferrin saturation (TSAT), total iron binding capacity (TIBC), and serum iron and ferritin levels were extracted as instrumental variables for iron parameters from meta-analyses of public genome-wide association studies. Individuals without myocardial infarction history, HF, or LV ejection fraction (LVEF) < 50% (n = 16,923) in the UK Biobank Cardiovascular Magnetic Resonance Imaging Study constituted the outcome dataset. The dataset included LV end-diastolic volume, LV endsystolic volume, LV mass (LVM), and LVM-to-end-diastolic volume ratio (LVMVR). We used a two-sample bidirectional MR study with inverse variance weighting (IVW) as the primary analysis method and estimation methods using different algorithms to improve the robustness of the results.
RESULTSIn the IVW analysis, one standard deviation (SD) increased in TSAT significantly correlated with decreased LVMVR (β = -0.1365; 95% confidence interval [CI]: -0.2092 to -0.0638; P = 0.0002) after Bonferroni adjustment. Conversely, no significant relationships were observed between other iron and LV parameters. After Bonferroni correction, reverse MR analysis showed that one SD increase in LVEF significantly correlated with decreased TSAT (β = -0.0699; 95% CI: -0.1087 to -0.0311; P = 0.0004). No heterogeneity or pleiotropic effects evidence was observed in the analysis.CONCLUSIONS We demonstrated a causal relationship between TSAT and LV remodeling and function in a preserved ejection fraction population. H eart failure (HF) is a clinically heterogeneous disease with high incidence, mortality, and socioeconomic burden. [1] Owing to developments in medical and health care, the aging trend is becoming increasingly evident in the population. Similarly, with the increasing incidence of diseases such as hypertension, diabetes, and heart disease, the population with heart failure and preserved ejection fraction (HFpEF) is increasing. [2][3][4] However, despite the confirmed diagnosis of HFpEF, its treatment remains challenging, partly owing to its diverse pathophysiological mechanisms. [5] Investigating risk variables associated with the occur-rence and development of HFpEF, particularly modifiable risk factors, should be expedited regarding medical obstacles.Iron deficiency (ID) is associated with various organic disorders, including HFpEF. Approximately 59% of patients with HFpEF have ID, which may be attributable to the influence of chronic inflammation and oxidative stress on iron storage. [6][7][8] A systematic review showed that iron insufficiency is associated with lower exercise tolerance and quality of life in patients with HFpEF. [9] Iron substantially influences mitochondrial functio...