Association of plasma interleukin-6 with infarct size, reperfusion injury, and adverse remodelling after ST-elevation myocardial infarction.

AIMS  Little is known about the clinical relevance of interleukin (IL)-6 in patients with acute ST-elevation myocardial infarction (STEMI). This study examined the possible associations of plasma IL-6 concentrations with infarct size (IS), reperfusion injury and adverse left ventricular remodelling (LVR), in STEMI patients treated with primary percutaneous coronary intervention (PCI). METHODS AND RESULTS We prospectively included 170 consecutive STEMI patients (median age 57 years, 14% women) treated with primary PCI between 2017 and 2019. Blood samples for biomarker analyses including IL-6 were collected on Day 2. Left ventricular ejection fraction (LVEF), IS, and reperfusion injury [microvascular obstruction (MVO) and intramyocardial haemorrhage (IMH)] were determined using cardiac magnetic resonance (CMR) imaging on Day 4. Left ventricular remodelling was defined as ≥10% increase in left ventricular end-diastolic volume from baseline to 4 months CMR follow-up. Patients with IL-6 concentrations ≥median (17 ng/L) showed a significantly lower LVEF (43% vs. 52%, P < 0.001), larger IS (22% vs. 13%, P < 0.001), larger MVO (1.9% vs. 0.0%, P < 0.001), and more frequent IMH (52% vs. 18%, P < 0.001). Left ventricular remodelling was more common in patients with IL-6 ≥ median (24% vs. 9%, P = 0.005). In both linear and binary multivariable regression analyses, IL-6 remained independently associated with lower LVEF [odds ratio (OR): 0.10, 95% confidence interval (CI) 0.02-0.42, P = 0.002], larger IS (OR: 5.29, 95% CI 1.52-18.40, P = 0.009), larger MVO (OR: 5.20, 95% CI 1.30-20.85, P = 0.020), with presence of IMH (OR: 3.73, 95% CI 1.27-10.99, P = 0.017), and adverse LVR (OR: 2.72, 95% 1.06-6.98, P = 0.038). CONCLUSIONS  High concentrations of circulating plasma IL-6 on Day 2 after STEMI were independently associated with worse myocardial function, larger infarct extent, more severe reperfusion injury, and a higher likelihood for LVR, suggesting IL-6 as a useful biomarker of more serious outcome and potential therapeutic target. CLINICAL TRIAL REGISTRATION https://clinicaltrials.gov/ct2/show/NCT04113356;NCT04113356.