中文摘要：

目的 ：探讨血浆cf-DNA的含量、完整性与ACS患者的关系及其对ACS的诊断价值。方法 ：提取62例ACS患者和39例正常对照者血浆cf-DNA,采用基于ALU序列的SYBR Green I实时荧光定量聚合酶链反应方法检测cf-DNA长、短片段（247bp、115bp）含量,并以ALU115作为cf-DNA总水平、以ALU247/115指数作为cf-DNA完整性指标,应用ROC曲线评估cf-DNA和cTnI对ACS的诊断价值,并分析cf-DNA与肌钙蛋白I（cTnI）、肌酸激酶同工酶（CK-MB）、肌红蛋白（Mb）的相关性。结果：ACS患者血浆cf-DNA含量[532.0（257.4-986.0）ng/m L]显著高于正常对照者[55.0（12.6-128.4）ng/m L],差异有统计学意义（P〈0.05）。血浆cf-DNA含量与cTnI（r=-0.32）、CK-MB（r=-0.20）、Mb（r=-0.34）无相关性。ACS患者ALU247/115指数[0.68（0.48-0.95）]显著高于正常对照者[0.36（0.26-0.53）],差异有统计学意义（P〈0.05）。cf-DNA含量、完整性曲线下面积（0.880、0.820）高于cTnI（0.736）,差异有统计学意义（P〈0.05）。结论：血浆cf-DNA含量、完整性与ACS相关。qPCR方法检测血浆cf-DNA的含量及其完整性对ACS的辅助诊断具有一定的价值。

英文摘要：

Objective： To investigate the expression and integrity of plasma cell-free DNA in acute coronary syndrome patients and evaluate the performance of diagnosis in patients with ACS. Methods： According to our protocol, we collect blood samples from 62 patients with ACS and 39 healthy controls. After extracting plasma cf-DNA, we use qPCR to detect the lever of cf- DNA long, short fragments（247 bp and 115 bp）, and choose the ALU115 fragment to present the total level of cf-DNA.. The index of ALU247/115 is used to stand for cf-DNA integrity. What＇s more, ROC curve is carried out to evaluate the diagnostic value of plasma cf-DNA and cTnI in patients with ACS. Besides that, we also analyze the correlations of cf-DNA with cardic Troponin I（cTnI）, creatine kinase isoenzyme（CK-MB） and myoglobin（Mb）. Results：The concentrations of cf-DNA in the plasma of ACS patients and the healthy controls were 532.0（257.4-986.0）ng/m L, and55.0（12.6-128.4）ng/m L, respectively. There was a significant difference between ACS patients and the health control（P〈0.05）.The ALU247/115 index of ACS patients was 0.68（0.48-0.95）, significantly higher than in the healthy control, namely0.36（0.26-0.53）,（P〈0.05）. No correlation was witnessed between cf-DNA and cTnI（r=-0.32）, CK-MB（r=-0.20）, Mb（r=-0.34）.The area under the Receiver Operating Characteristic（ROC） curve for discriminating patients with ACS from the healthy controls by plasma cf-DNA was 0.880、0.820, which was significantly larger than in cTnI（0.736）. Conclusions： The concentration and integrity of cf-DNA are associated with ACS. Detection plasma cf-DNA concentration and integrity with qPCR may become a valuable complementary diagnosistic method for discriminate ACS from healthy individuals.