目的 比较依诺肝素和普通肝素对不稳定心绞痛及非ST段抬高心肌梗死患者外源性凝血系统和血小板活性的作用差异，及其对临床事件发生的预测价值。方法 入选病例分为依诺肝素组和普通肝素组，于用药前及用药后不同时间点分别检测抗Ⅹa因子、von Willebrand 因子(vWF)和游离组织因子途径抑制因子（free-TFPI）水平，分析检测指标与患者临床事件发生的关系。结果 在依诺肝素组，抗Ⅹa因子在用药后3 h即达到有效水平；在用药48 h后3 h时间点，抗Ⅹa因子仍维持在有效浓度范围内，且显著高于普通肝素组（P<0.05）；依诺肝素组用药后vWF浓度显著低于普通肝素组（P<0.05）。有临床事件组⊿vWF显著高于无临床事件组（P<0.01），⊿vWF与30 d临床事件相关（OR=1.373, P<0.05）。结论 与普通肝素比较，依诺肝素可更为有效地阻断外源性凝血途径，对抗血小板黏附聚集。早期vWF增加对不稳定心绞痛及非ST段抬高心肌梗死患者30 d临床事件发生有一定的预测价值。

Objective To compare the differences of effects of enoxaparin and unfractionated heparin on the extrinsic coagulation system and activity of platelet in patients with unstable angina pectoris and non-ST-elevation acute myocardial infarction and the predictive value of two types of heparins for the occurrence of clinical events. Methods Selected cases were divided into the enoxaparin group and unfractionated heparin group. Levels of anti-Ⅹa factor, von Willebrand factor (vWF), free tissue factor pathway inhibitor (free-TFPI) were detected at different time points before and after administration. The correlation of detected indexes and clinical events of patients was analyzed. Results The anti-Ⅹa level of the enoxaparin group reached the efficient level 3 h after administration; remained within the efficient range at 3 h time point 48 h after administration; and was significantly higher than that of the unfractionated heparin group (P<0.05). The vWF level of the enoxaparin group was significantly lower than that of the unfractionated heparin group (P<0.05). The ⊿vWF of patients with clinical events was significantly higher than that of patients without clinical events (P<0.01). The ⊿vWF was relevant to clinical events occurring within 30 d (OR=1.373, P<0.05). Conclusion Compared with unfractionated heparin, enoxaparin can block the extrinsic coagulation pathway and prevent the platelet adhesion and aggregation more efficiently. The increase of vWF in early stage may be used to predict clinical events occurring within 30 d for patients with unstable angina pectoris and non-ST-elevation acute myocardial infarction.