Christenson R H, Newby L K, Ohman E M
Department of Pathology, University of Maryland School of Medicine, Baltimore, USA.
Md Med J. 1997;Suppl:18-24.
Biochemical markers provide clinicians with an important tool for the assessment of acute coronary syndromes. Biochemical markers, including total creatine kinase (total CK), creatine kinase-MB (CK-MB), the MB isoforms, and myoglobin, as well as the troponins--cardiac troponin T (cTnT) and cardiac troponin I (cTnI)--are all used for assessment of the suspected acute myocardial infarction (AMI) patient. In the context of myocardial infarction (MI) diagnosis, total CK is a relatively sensitive marker, but it lacks myocardial specificity because skeletal muscle contains high concentrations of CK. CK-MB is the benchmark for biochemical markers and has both high sensitivity and specificity; however, CK-MB is also present in skeletal muscle and is not diagnostic until eight to twelve hours after onset of symptoms. The MB isoforms are diagnostic earlier but have the same cardiac specificity issues as CK-MB. Myoglobin becomes abnormal about one hour after onset of symptoms and is a sensitive marker for MI; however, myoglobin is cleared quickly and is not cardiac specific. Both cTnT and cTnI are cardiac specific and show high sensitivity and specificity for MI. Risk stratification of acute coronary syndrome patients is another role for biochemical markers; CK-MB, cTnT and cTnI have all been proposed for this function. Compared with CK-MB, both cTnT and cTnI are better able to predict short-term mortality following the index event. Analysis using a logistic regression model that included the electrocardiogram, cTnT, and cTnI showed that cTnT was the most useful marker for risk stratification. Finally, cTnT was reported to be able to predict which patients will benefit from treatment with regimens of low molecular weight heparin.
生化标志物为临床医生评估急性冠脉综合征提供了一项重要工具。生化标志物，包括总肌酸激酶（总CK）、肌酸激酶同工酶MB（CK-MB）、MB亚型以及肌红蛋白，还有肌钙蛋白——心肌肌钙蛋白T（cTnT）和心肌肌钙蛋白I（cTnI）——均用于评估疑似急性心肌梗死（AMI）患者。在心肌梗死（MI）诊断方面，总CK是一种相对敏感的标志物，但它缺乏心肌特异性，因为骨骼肌中含有高浓度的CK。CK-MB是生化标志物的基准，具有高敏感性和特异性；然而，CK-MB也存在于骨骼肌中，在症状发作后8至12小时才具有诊断意义。MB亚型诊断更早，但存在与CK-MB相同的心肌特异性问题。肌红蛋白在症状发作后约1小时就会出现异常，是MI的敏感标志物；然而，肌红蛋白清除迅速，并非心肌特异性标志物。cTnT和cTnI均具有心肌特异性，对MI表现出高敏感性和特异性。对急性冠脉综合征患者进行危险分层是生化标志物的另一项作用；CK-MB、cTnT和cTnI均被提议用于此功能。与CK-MB相比，cTnT和cTnI都更能预测首次事件后的短期死亡率。使用包含心电图、cTnT和cTnI的逻辑回归模型进行分析表明，cTnT是危险分层最有用的标志物。最后，据报道cTnT能够预测哪些患者将从低分子量肝素治疗方案中获益。
