Plasma interleukin 6 levels are associated with cardiac function after ST-elevation myocardial infarction

Background and aimsMyocardial infarction triggers an inflammatory response involved in cardiac repair. We studied the association of the interleukin 6 (IL-6) cascade with infarct size and cardiac function after ST-elevation myocardial infarction (STEMI).MethodsIn 369 STEMI patients IL-6, soluble IL-6 receptor (sIL-6R), and soluble glycoprotein (sgp) 130 were measured at baseline (hospital admission), 24h, 2 weeks, 7 weeks, 4 months, and 1year post-PCI and sIL-6R/IL-6 ratio was calculated. At 4 months, infarct size and left ventricular ejection fraction (LVEF) were assessed by magnetic resonance imaging. Diastolic function (E/e) was determined by echocardiography.ResultsHospital admission levels for IL-6, sIL-6R, sgp 130 were 3.7pg/ml (IQR 2.1-6.7pg/ml), 51.6ng/ml (IQR 37.3-69.0ng/ml), and 332ng/ml (IQR 280-399ng/ml), respectively. 24h after admission, IL-6 had increased threefold compared to baseline (p<0.001) and returned below baseline (p<0.001) 2 weeks after STEMI. sIL-6R and sgp130 levels at 24h remained similar to baseline but were increased at 2 weeks (p<0.001; p<0.001, respectively). IL-6 and sIL-6R/IL-6 ratio at 24h were independently associated with infarct size [ 5.4 (95% CI 3.3-7.5); p<0.001, -4.0 (95% CI -6.1 to -1.9); p<0.001, respectively]. Higher levels of IL-6at 24h were associated with lower LVEF [ -4.2 (95% CI -6.7 to -1.8); p=0.001].ConclusionsHigher IL-6 and lower sIL-6R/IL-6 ratio early after presentation with STEMI are indicative for larger infarct size and decreased cardiac function at 4 months.