The pathogenic mechanisms underlying cardiovascular diseases involve significant alterations in myocardial gene and protein expression. Proteomics analysis can define new protein and peptide changes associated with cardiac pathology, including myocardial infarction. The aim of the present study was to analyze serum proteome of patients with ST-Elevation myocardial infarction (STEMI). Serum samples were collected from STEMI patients (age 65.0+/-10.3) at 5.3+/-2.7 hours after the onset of typical chest pain and before initiating standard therapy. Ten age- and sex-matched donors were used as controls. The samples were albumin- and IgG-depleted. Isotope-coded affinity tag method was employed to label cysteine residues and liquid chromatography-Tandem Mass Spectrometry analysis was performed to measure the labeled proteins. Our proteomic approach identified increased levels of vitamin D-binding protein precursor (VDB) in the serum of STEMI patients when compared to control donors. Western blot analysis confirmed the increase in VDB protein in STEMI patients. Moreover, fresh thrombotic plaques, obtained during primary angioplasty, showed high expression of VDB protein. Mechanistically, VDB protein reduces platelet aggregation and prolongs coagulation time ex vivo.