Abstract： ST-segment elevation myocardial infarction (STEMI)is usually caused by acute occlusion of an infarct-related coronary artery (IRA),resulting from rupture or erosion of an atherosclerotic plaque and subsequent platelet aggregation and thrombosis.1-3Prompt reperfusion is the key aspect of the optimal management,4-7 and timely expert primary percutaneous coronary intervention (PCI) becomes the best reperfusion strategy with respect to improvement in survival and reduction of combined clinical endpoints in the treatment of STEMI.8-11 Given the high thrombotic risk of patients with STEMI,pretreatment with a high clopidogrel loading dose before primary PCI was advised to reduce distal thrombotic embolization and angiographic no-reflow and improve clinical outcomes.12,13 The use of adjunctive intravenous glycoprotein (GP) Ⅱb/Ⅲa inhibitors following oral dual-antiplatelet therapy enhances thrombus disaggregation by inhibiting fibrinogen binding to the active receptor complex and subsequently disrupting platelet cross-linking,14 and improves IRA patency and myocardial perfusion,14 and has been recommended as class Ⅱa (at the time of primary PCI) or Ⅱb (before primary angiography and PCI)indication in the recent practice guidelines for the management of patients with STEMI.9,10 Tirofiban (a small-molecule platelet GP Ⅱb/Ⅲa inhibitor) seems even more attractive,because of its consistent and rapidly reversible platelet inhibition at increased dose and efficient penetration into the platelet-fibrin thrombus.15 In a broad population of largely unselected patients undergoing primary PCI for STEMI,tirofiban was associated with a noninferior complete resolution of ST-segment elevation (an indirect measure of myocardial reperfusion after PCI14,16) compared with abciximab,17 and was well tolerated and effective in reducing ischemic acute coronary syndrome complications in patients with mild-to-moderate renal insufficiency.18 Previous studies have shown that an upstream low dose of tirofiban favorably ameliorates IRA patency and reperfusion of the infarct area compared with down-stream use,19 and routine initiation of high-bolus dose of tirofiban could further improve clinical outcome after primary PCI.20 These observations highlight that further platelet aggregation inhibition besides high-dose clopidogrel is mandated in patients with STEMI undergoing primary PCI.