IntroductionRegarding the inflammatory mechanisms involved in ischemic heart disease, currently the leukocyte count is the subject of studies related to its association with the prognosis and mortality of ST segment elevation myocardial infarction (STEMI). Our aim is correlate the leukocyte count rise with the size of STEMI, evaluated with the area under the curve (AUC) and the peak of necrosis markers release.Material and methodsThis study is a sub-analysis of the TETHYS trial, a clinical trial that evaluated the effects of methotrexate in STEMI. We evaluated the correlation between quantitative variables with Pearson’s correlation, and the variables that did not follow a normal distribution were subjected to logarithmic transformation to base 10. The value of p < 0.05 indicated statistical significance.ResultsMales accounted for 73% of the participants, who had an average age of 59 years. A total of 58% were hypertensive and 53% smokers. The leukocyte count at hospital admission was significantly correlated with the AUC creatine kinase (CK) (r = 0.256, p = 0.021), troponin AUC (r = 0.247, p = 0.026), peak CK (r = 0.270, p = 0.015) and troponin peak (r = 0.233, p = 0.037). The leukocyte count at 72 h was significantly correlated with CK AUC (r = 0.238, p = 0.032), AUC of MB portion of CK (r = 0.240, p = 0.031) and peak CK (r = 0.224, p = 0.045).ConclusionsWhite blood cell count correlates with STEMI size assessed by serial cardiac biomarker levels.