Hsu L F, Koh T H, Lim Y L
Department of Cardiology, National Heart Centre, Singapore.
Ann Acad Med Singap. 2000 Jul;29(4):421-7.
Up to 40% of patients with acute myocardial infarction (AMI) present with non-diagnostic electrocardiograms (ECGs). The diagnosis in such cases is usually made with the aid of biochemical markers. Newer and more rapid assays for such markers have now enabled testing to be done on-site instead of in the laboratory. This potentially enables the clinician to rapidly diagnose and triage patients. We evaluated the diagnostic precision of this point-of-care testing strategy using one such analyser, the Stratus CS (Dade Behring) in a prospective study.
The study population consisted of 51 consecutive patients admitted for suspected AMI with non-diagnostic ECGs. Two blood samples from each patient were drawn simultaneously on admission. The first sample was assayed for myoglobin, troponin I (TnI) and creatine kinase-MB (CKMB) mass by the point-of-care instrument (Stratus CS), and the second sample was sent for standard testing for AMI, comprising a troponin-T (TnT) qualitative test and the analysis of CKMB by the hospital laboratory. Utilising the recommended cut-off values for the individual assays, the results of these 2 sets of tests were evaluated based on whether they were positive or negative for AMI and compared against the patient's final diagnosis at discharge. Various combinations of markers were assessed.
On evaluation of individual markers, myoglobin was the most sensitive (75%) at 0 to 6 hours after onset of symptoms, while TnI (95%), TnT (80%) and CKMB-mass (90%) performed better at 7 to 12 hours. Point-of-care testing utilising a combination of markers was highly sensitive and specific. Both dual-marker panels of myoglobin with TnI and myoglobin with CKMB-mass yielded equivalent overall sensitivities and specificities of 90% and 95% respectively. A triple-marker panel of myoglobin, TnI and CKMB-mass had a sensitivity of 93% and specificity of 95%. All point-of-care testing panels had good positive and negative predictive values, and showed comparable diagnostic efficacy with the standard testing presently utilised for the diagnosis of AMI. The average time for results to become available was up to 26 minutes for point-of-care testing and 65 minutes for standard testing.
Point-of-care testing utilising a panel of 2 or 3 cardiac markers has comparable diagnostic precision to the presently utilised testing strategy for AMI, with earlier availability of results.
高达40%的急性心肌梗死（AMI）患者心电图（ECG）表现不具有诊断性。此类病例的诊断通常借助生化标志物。针对此类标志物更新且更快速的检测方法现已能够在现场而非实验室进行检测。这潜在地使临床医生能够快速诊断并对患者进行分诊。我们在一项前瞻性研究中使用一款此类分析仪——Stratus CS（德灵公司）评估了这种即时检测策略的诊断准确性。
研究人群包括51例因疑似AMI入院且心电图不具有诊断性的连续患者。每位患者入院时同时采集两份血样。第一份血样通过即时检测仪器（Stratus CS）检测肌红蛋白、肌钙蛋白I（TnI）和肌酸激酶同工酶MB（CKMB）质量，第二份血样送去进行AMI的标准检测，包括肌钙蛋白T（TnT）定性检测以及由医院实验室分析CKMB。利用各检测项目推荐的临界值，根据这两组检测结果对AMI是阳性还是阴性进行评估，并与患者出院时的最终诊断进行比较。对各种标志物组合进行了评估。
对单个标志物进行评估时，症状发作后0至6小时，肌红蛋白最敏感（75%），而在7至12小时，TnI（95%）、TnT（80%）和CKMB质量（90%）表现更佳。利用标志物组合的即时检测具有高度敏感性和特异性。肌红蛋白与TnI以及肌红蛋白与CKMB质量的双标志物组合总体敏感性和特异性分别为90%和95%，二者相当。肌红蛋白、TnI和CKMB质量的三标志物组合敏感性为93%，特异性为95%。所有即时检测组合均具有良好的阳性和阴性预测值，并且与目前用于诊断AMI的标准检测显示出相当的诊断效能。即时检测结果可得的平均时间最长为26分钟，标准检测为65分钟。
利用2种或3种心脏标志物的即时检测与目前用于AMI的检测策略具有相当的诊断准确性，且结果可得时间更早。
