Objective: ST-segment elevation myocardial infarction (STEMI) is an important cause of morbidity and mortality. Platelet (PLT) activation and thrombosis have important roles in the process of atherosclerosis that is one of the most important cause of acute ischaemic syndromes. PLT count is related with inflammation and mean platelet volüme (MPV) is an important marker of PLT activation. Both parameters are found to be related with increased cardiovascular risk. In this study we aimed to investigate clinically usability of a new parameter:MPV/PLT ratio, in the diagnosis of patients with Troponin I elevated STEMI.

Material and Methods: 92 male patients with STEMI-underwent percutaneous coronary intervention (PCI) successfully and 75 healthy subjects were enrolled in the study. T-test was used to determine significant differences between the groups for data with normal distribution and Spearmans analysis was used to deterMIne the correlations between the variables. Independent predictive factors were found for PLT, MPV and MPV/PLT ratio of patients with STEMI.Characteristic ROC curves were performed, optimal cut-off points were determined.

Results: Significant differences were determined for PLT, MPV and MPV/PLT ratio levels of patients (P<0.001). Optimal cut off points were 262.5 for PLT(AUC 0.488;sensitivity 50%, specifity 52%);10.45 for MPV(AUC 0.700, sensitivity 69%, specifity 54%) and 0.043 for MPV/PLT(AUC 0.788, sensitivity 71%, specifity 64%).

Conclusion: MPV/PLT ratio was demonstrated to be associated with patients with STEMI with a higher spesifity and sensitivity than PLT and MPV. Also, higher MPV/PLT ratio was associated with greater SYNTAX score.We suggest that an elevated level of MPV/PLT ratio may be of benefit to predict severity of these patients.