Objectives To compare the efficacy and safety of upstream tirofiban with downstream tirofiban in patients with non- ST-segment elevation acute coronary syndromes (NSTE-ACS) at high-risk undergoing percutaneous coronary intervention (PCI). Methods Two hundred and four patients with NSTE-ACS at high-risk undergoing PCI were randomized to upstream (4 -6 hours before coronary angiography) tirofiban or downstream (with the guidewire crossing the lesion) tirofiban. We evaluated myocardial damage after PCI by qualitatively analyzing cardiac troponin I (cTnI) and MB isoenzyme of creatine kinase (CK-MB). Platelet aggregation inhibition and thrombolysis in myocardial infarction (TIMI) flow grade were assessed. The incidences of major adverse cardiac events (MACE) at 24-hour, 90-day and 180-day after PCI were followed up. The incidences of bleeding complications and thrombocytopenia during tirofiban administration were recorded. Results There were 102 patients with NSTE-ACS randomly assigned to upstream group and downstream group respectively. The peak serum levels of cTnI within 48 hours after PCI were significantly lower with upstream tirofiban than downstream tirofiban (0.34 vs 0. 61 ; P 〈 0.05 ). Post-procedural cTnI elevation within 48 hours was significantly less frequent among patients who received upstream tirofiban than downstream tirofiban (63 % vs 82%, P 〈 0. 05 ). The peak serum levels of CK-MB as well as post-procedural CK-MB elevation within 48 hours after PCI were not significantly different between the two groups ( 15 vs 18 and 38% vs 43% ; respectively; P 〉 0. 05 ). ECG changes and the inhibition of platelet aggregation between two groups were similar ( P 〉 0.05 ). Although the inci- dences of MACE at 90-day and 180-day after PCI were not statistically different, they were consistently lower with upstream tirofiban (3 % vs 6% and 6% vs 16% ; P 〉 0.05 ). The incidences of bleeding complications and thrombocyto- penia were similar in the two groups ( 11% vs 9% ; P 〉 0.05 ). Conclusions Among patients with NSTE-ACS at high-risk undergoing PCI, upstream tirofiban is associated with attenuated myocardial damage without increasing complications. ( S Chin J Cardiol 2009; 10(4) : 179 -185) 相似文献