心肌肌钙蛋白诊断和除外急性心肌梗死界限值的探讨

目的:探讨心肌肌钙蛋白(cTn)诊断和除外急性心肌梗死(AMI)的界限值。方法:因心血管疾病住院及尿毒症透析患者共334例,分为AMI组30例、心绞痛组90例、心力衰竭组56例、心律失常组41例、高血压组97例、尿毒症组20例。入院次日清晨空腹抽取血标本,同时测量cTnI、cTnT及肌酸激酶同工酶(CK-MB)。分析比较cTnI、cTnT及CK-MB达到正常参考人群数值的第95百分位数及2倍于此数值时对于诊断AMI的敏感性、特异性及准确性。结果:AMI组与其他各组相比,cTn和CK-MB增高差异有统计学意义(P<0.05);除AMI组外其他组患者cTnI、cTnT和CK-MB测定值均有部分高于正常参考人群数值的第95百分位数,且与AMI组有重叠。结论:cTnI和cTnT达到正常参考人群数值的第95百分位数时对AMI诊断的敏感性无明显差异,特异性cTnT高于cTnI。CK-MB的敏感性不高但是特异性很高,与cTnT类似,仍可做AMI排除诊断用。建议心肌标志物应该有2个界限值,一个是目前的正常参考人群数值的第95百分位数,为诊断AMI的界限值;另一个是2倍于此数值,用于排除非缺血性心肌损伤。

Value of cTn in diagnosis of acute myocardial infarction

Objective:To define a cut point of cTn and creatine kinase-myocardial band(CK-MB) in diagnosis of acute myocardial infarction(AMI). Method:The concentrations of cTnI,cTnT,and CK-MB in the serum of the patients who were admitted to the Second Affiliated Hospital of Dalian Medical University during continuous three months were measured.Three hundred and thirty-four cases were collected.All patients were divided into 6 groups: 30 cases in AMI group,90 in angina pectoris group,56 in heart failure group,41 in cardiac arrhythmia group,97 in hypertensive group,and 20 in uremia group.Man-Whitney the U non-parametric test was processed and exper-iment fourfold table method was used to analyze the sensitivity,specificity and the accuracy of cTnI,cTnT and CK-MB respectively. Result:The serum cTn and CK-MB concentration in AMI patients were significantly higher compared with other groups(P<0.05),but the values of them in the other groups had overlapped with the AMI group. Conclusion:Both cTnI and cTnT had high sensitivity in diagnosing AMI,but the specificity of cTnT was higher than cTnI(99.6% vs 81.3%).Therefore cTnT was recommended for AMI exclusion.The CK-MB in diagnosing AMI was not high in sensitivity but high in specificity,similarly as cTnT.The value of cTnT and CK-MB exceeding twice 95th percentile referent value could be accepted in AMI diagnosis.We suggest that cTn should have two critical values,one is for diagnosis of AMI and another for excluding non-ischemia damage of myocardium.