Relationship between serum interleukin-6 levels and severity of STEMI undergoing percutaneous coronary intervention: a prospective observational study

Inflammation plays a central role in the pathophysiology of ST-elevation myocardial infarction (STEMI). Interleukin-6 (IL-6) is a key pro-inflammatory cytokine linked to adverse cardiovascular outcomes. To investigate the association between admission IL-6 levels and clinical severity, short-term prognosis, and major adverse cardiovascular events (MACEs) in STEMI patients undergoing primary percutaneous coronary intervention (PCI). This prospective observational study included 60 STEMI patients undergoing PCI. Serum IL-6 was measured upon admission. Patients were stratified into high and low IL-6 groups using the median value (20.20 ng/L) as cutoff. Clinical severity was assessed using the TIMI risk score and Killip classification. Patients were followed for 4 months for MACEs (death, recurrent MI, or heart failure). IL-6 was also analyzed as a continuous variable in regression models, and multivariable analysis was performed with a limited number of predictors due to the small number of events. The high IL-6 group had significantly higher TIMI scores (6.5 vs. 5.0, p = 0.011), more anterior infarctions (60.0% vs. 23.3%, p = 0.004), elevated inflammatory markers, and more frequent heart failure (60.0% vs. 0.0%, p < 0.001). MACEs occurred in 7 patients with high IL-6 versus 1 in the low IL-6 group ( p = 0.023). Elevated IL-6 remained associated with MACEs after adjustment for selected clinical variables; however, the number of events was limited. Elevated admission IL-6 levels are associated with increased clinical severity and poorer short-term outcomes in STEMI patients undergoing PCI. These findings should be interpreted with caution due to the limited sample size and number of events. IL-6 may serve as a potential prognostic biomarker; however, its incremental predictive value beyond established risk scores remains uncertain. Further studies with larger cohorts and longer follow-up are required to validate these findings.