Role of Non-Transferrin-Bound Iron in the pathogenesis of cardiotoxicity in patients with ST-elevation myocardial infarction assessed by Cardiac Magnetic Resonance Imaging

BACKGROUND: Hereditary hemochromatosis, thalassemia and myelodysplastic syndromes represent disease models with evidence of iron-related heart failure. Non-Transferrin Bound Iron (NTBI) induces cardiac toxicity through the production of reactive oxygen species and lipid peroxidation. In ST-elevation acute myocardial infarction (STEMI) with evidence of microvascular obstruction (MVO) and hemorrhage (HEM), HEM may be a source of iron-related cardiac toxicity through NTBI and pro-inflammatory mediators. AIM OF THE STUDY: The study aims to assess NTBI in patients with STEMI and its possible relationship with MVO and HEM. METHODS AND RESULTS: NTBI, LPO-Malondialdehyde (MDA) and interleukin-6 (IL-6) were assessed in 15 patients with STEMI immediately before primary percutaneous coronary intervention (PPCI) and at 3, 6, 9, 12, and 24h post-PPCI. Cardiac Magnetic Resonance (CMR) was performed at 5days and 6months after STEMI. Myocardial edema and HEM were assessed by T2 and T2* mapping. MVO and necrotic area were assessed by early and late gadolinium enhancement (LGE). NTBI was detected in 13/15 patients with the highest values in 4 patients with evidence of MVO and HEM. NTBI levels were significantly related to CK-MB and troponin T values. NTBI kinetics appeared to be different in patients with MVO and HEM (7/15 patients), with a peak value at 6h after PCI, in comparison with those with no evidence of MVO and HEM, in whom NTBI values were lower and remained indeterminable after the first 24h. CONCLUSIONS: The detection of elevated NTBI values in patients with STEMI, MVO and HEM suggests a possible role of iron cardiotoxicity in myocardial damage.