In the very interesting report published in the Am J Cardiol 2013, it was found that in patients with anterior wall acute myocardial infarction, elevated white blood count on admission is a powerful independent predictor of infarct size measured with cardiac magnetic resonance imaging 30 days after primary percutaneous coronary intervention. A previous study has also shown that in patients with ST-segment elevation acute myocardial infarction undergoing percutaneous coronary intervention, elevated baseline white blood count is an independent predictor of infarct size, as assessed by peak creatinine phosphokinase level, and of 1-year cardiac mortality, noncardiac mortality, and major bleeding. These results suggest a key role for inflammation in coronary artery disease. However, differential count was not available in these studies, and therefore, assessing the relative impact of white blood count subpopulations on infarct size was not reported.

Indeed, neutrophil/lymphocyte ratio >3.3 was found to be an independent predictor of impaired coronary flow after primary percutaneous coronary intervention and of in-hospital major adverse cardiac events in patients with ST-segment elevation myocardial infarction.

Previous studies have shown that eosinophils may play an important role in coronary occlusion by promoting thrombus growth. In this study, eosinophils were observed in 106 (64.2%) of 165 samples. In a genome-wide association study for sequence variants affecting eosinophil counts in blood, it was found that a nonsynonymous “single nucleotide polymorphism” at 12q24, in SH2B3, was associated significantly with myocardial infarction. Eosinophils are pleiotropic multifunctional leukocytes involved in initiation and propagation of inflammatory responses and thus have important roles in the pathogenesis of inflammatory diseases. It is known that eosinophils are bone marrow–derived granulocytic leukocytes and express H4 histamine receptors. These receptors facilitate eosinophil chemotaxis toward mast cells, which are the major producers of an array of inflammatory soluble mediators. Soluble mediators secreted by mast cells and eosinophils modulate also reciprocal interactions between these 2 cells in the so-called allergic effector unit.

Therefore, differential white blood count and especially eosinophils should be always considered in all relative studies concerning acute coronary syndromes. Eosinophils are essential for elucidation of the origin of inflammation because denote hypersensitivity inflammation.