In line with previous studies, we found the platelet proteome to be relatively stable at the time of STEMI.20,21 In the only other comparable studies, 2-dimensional difference in-gel electrophoresis techniques found <50 differentially regulated proteins in STEMI, without correcting for multiple testing.20,21 This is the first study demonstrating increased protein levels of S100A8 and S100A9 in platelets during STEMI, doubling in abundance when comparing the time of STEMI with stable CAD. Here, S100A9 is linked to coronary artery disorder.