Coronary and Peripheral Venous Inflammatory Biomarkers in Acute Myocardial Infarction: Associations with Myocardial Injury, Cardiac Function, and Clinical Outcomes

(1) Background: Interleukin-6 (IL-6) links innate immune activation to myocardial injury and adverse outcomes after acute myocardial infarction (AMI), yet the relationship between local intracoronary and systemic peripheral IL-6, and their prognostic value, remains unclear. (2) Methods: This prospective single-center study aimed to compare intracoronary and peripheral venous IL-6 and other inflammatory biomarkers in AMI, included 83 consecutive STEMI (ST-elevation myocardial infarction) or NSTEMI (non ST-elevation myocardial infarction) patients undergoing coronary angiography. Paired intracoronary and peripheral venous samples were obtained before revascularization and analyzed for IL-6, CRP, and ferritin, and correlated with LVEF (left ventricle ejection fraction), NT-proBNP, and a 30-day composite endpoint (death or heart failure hospitalization). (3) Results: Peripheral IL-6 exceeded intracoronary levels in 86.7% of patients (p < 0.001), with both peripheral IL-6 and the venous-to-coronary difference higher in STEMI than NSTEMI. IL-6 in both compartments correlated inversely with LVEF and positively with NT-proBNP and troponin I. Patients reaching the composite endpoint (10.8%) had markedly higher IL-6 and CRP. ROC analysis showed discriminatory ability for the endpoint by intracoronary and peripheral IL-6. (4) Conclusions: Intracoronary and peripheral IL-6 are associated with infarction phenotype, ventricular dysfunction, and short-term outcomes in AMI, supporting its role as an early prognostic biomarker.