Dynamics of serum interleukin-6 level in patients with acute myocardial infarction.

Background: Interleukin-6 (IL-6) is a key cytokine in the initiation of the acute-phase reaction that accompanies myocardial infarction. The study was designed to evaluate changes in serum IL-6 in patients with myocardial infarction and to compare IL-6 alterations with serum creatine kinase (CK) activity. Methods: Serum IL-6 level and CK activity were measured in 19 males with acute myocardial infarction. Blood was taken on the 1st, 3rd, 5th, 7th and 21st days of the disease. Control values were obtained from 30 age-matched healthy males. IL-6 was determined according to the ELISA method and CK was measured with a routine procedure. Results: Serum IL-6 was found to increase on the 1st and 3rd days of the disease, followed by some decline on days 5-21. However, the last values measured were still higher than those in the controls. Patients with transmural myocardial infarction had higher IL-6 levels than those with non-Q myocardial infarction. There was no difference in serum IL-6 in patients with myocardial infarction of the inferior cardiac wall and of the anterior cardiac wall. A correlation was found between IL-6 level and CK activity in the patients, especially on the 1st and 3rd days of the disease. Conclusion: Serum IL-6 increases in patients with myocardial infarction, and this elevation seems to be related to the mass of the affected myocardium. The highest increase is found during the first days of the disease, although the enhanced IL-6 level lasts for at least 3 weeks, probably reflecting the healing process of the myocardium. The clinical value of IL-6 determination does not seem to exceed that of the indices commonly used.