一种灵敏的肌钙蛋白I方法对心肌梗死诊断的价值

Evaluation of a new generation cardiac troponin I assay in the diagnosis of acute myocardial infarction

目的:评价新一代ACCESSAccuTnI化学发光测定试剂的检测性能和诊断急性心肌梗死(AMI)的敏感度和特异度。方法:在ACCESS全自动化学发光免疫分析仪上测定心肌肌钙蛋白I(cTnI)值,评价检测线性,乳糜、黄疸、溶血和抗凝剂对检测的干扰,试剂稳定性,功能灵敏度和10%的变异,健康人97.5%和99%分位值。测定AMI组和非AMI组的cTnI水平,应用受试者工作特征曲线(ROC曲线)分析cTnI对AMI的诊断敏感度和特异度。结果:检测线性0～50μg/L;黄疸、乳糜和溶血对测定结果没有显著影响,肝素抗凝血浆与血清测定结果差异无显著性(P<0.05);血浆样本定期保存于25℃可稳定24h,4℃稳定3d,-20℃时至少稳定1个月;cTnI呈偏态分布,第99百分位点值为0.047μg/L,相对应的日内变异系数(CV)为10%,日间CV为14%;ROC分析结果示cTnI浓度为0.1μg/L时诊断ST段抬高心肌梗死的敏感度、特异度分别为96%和84%,为最佳诊断临界值;而诊断非ST段抬高心肌梗死的最佳诊断临界值为0.06μg/L,敏感度、特异度为87.7%和80.2%。结论:本测定方法稳定,具有较好的抗干扰能力,对心肌梗死的诊断具有较高的灵敏度和特异度。

Objective To evaluate the analytical performance of a new generation cardiac troponin I assay and the sensitivity and specificity of cTnI in the diagnosis of acute myocardial infarction （AMI）. Methods The 97.5 and 99 percentile upper reference limits （URLs）, the sensitivity, the imprecision, the linearity, the stability and the interference response of the cTnI assay were evaluated at automated micropartical chemiluminescent immunoassay analyzer of ACCESS.The cTnI was examined in the AMI patients and the controls, and the data were then analyzed with receiver operating characteristic （ROC） curve statistical software. Results The assay was linear to 50 μg/L. Jaundice, chyle and hemolysis had no influence to the results. The assay had no significant difference between serum and heparin plasma（P〈0.05）. The blood samples could stably stored at 25℃ for at least 24 hours, at 4℃ for 3 days or at -20℃ for at least 1 month. The 97.5 percentile URL was 0.02 μg/L （CV=19%）, and the 99 percentile URL was 0.047 μg/l, （CV=14%）. The ROC curve showed that the sensitivity and the specificity of the diagnostic cut-off point of cTnI both suqmssed 80%. The area under the curve was beyond 0.9. The optimal cut-off was 0.1 μg/L and 0.06 μg/L in the diagnosis of STEMI and NSTEMI. The sensitivity and the specificity were 96% and 84% respectively in the diagnosis of STEMI, and 87.7% and 80.2% respectively in the diagnosis of NSTEMI. Conclusions Beckman Coulter ACCESS AccuTnI assay is sensitive and stable with high sensitivity and specificity in the diagnosis of acute myocardial intarction.