Sallach Susan M, Nowak Richard, Hudson Michael P, Tokarski Glenn, Khoury Nabil, Tomlanovich Michael C, Jacobsen Gordon, de Lemos James A, McCord James
University of Texas at Southwestern, Dallas, Texas, USA.
Am J Cardiol. 2004 Oct 1;94(7):864-7. doi: 10.1016/j.amjcard.2004.06.019.
We sought to determine the sensitivity of a change in myoglobin for acute myocardial infarction (AMI) in patients who had normal levels of troponin I at presentation. Myoglobin increases as soon as 1 to 2 hours after symptom onset in AMI. The change in myoglobin may help identify AMI in patients with normal cardiac levels of troponin I on admission. A total of 817 consecutive patients who were examined in the emergency department for possible AMI were studied. In patients whose electrocardiograms were nondiagnostic, we measured levels of myoglobin and cardiac troponin I at presentation, at 90 minutes, and at 3 and 9 hours. Patients whose initial levels of myoglobin (<200 ng/ml) and cardiac troponin I (<0.4 ng/ml) were normal underwent receiver-operating characteristic curve analysis to determine the best cutpoint for a myoglobin increase from 0 to 90 minutes. Overall, 75 patients (9%) were diagnosed with AMI, including 27 patients with normal cardiac levels of troponin I at presentation. An increase of 20 ng/ml of myoglobin from 0 to 90 minutes provided maximal diagnostic utility in patients who did not have increased levels of myoglobin or cardiac troponin I at presentation. In the absence of an increased level of cardiac troponin I or myoglobin at presentation in the emergency department, a change >or=20 ng/ml of myoglobin at 90 minutes produced 83.3% sensitivity, 88.6% specificity, and 99.5% negative predictive value for AMI. The combined sensitivity of levels of cardiac troponin I and myoglobin and a change >or=20 ng/ml of myoglobin over 90 minutes was 97.3%. In emergency department patients with normal cardiac levels of troponin I at presentation, a change in myoglobin provides a highly accurate diagnosis of AMI within 90 minutes.
我们试图确定在就诊时肌钙蛋白I水平正常的患者中，肌红蛋白变化对急性心肌梗死（AMI）的敏感性。在AMI中，症状发作后1至2小时肌红蛋白就会升高。肌红蛋白的变化可能有助于识别入院时肌钙蛋白I心脏水平正常的患者中的AMI。对在急诊科接受检查以排查可能AMI的817例连续患者进行了研究。对于心电图无诊断意义的患者，我们在就诊时、90分钟时、3小时和9小时测量了肌红蛋白和心脏肌钙蛋白I的水平。初始肌红蛋白水平（<200 ng/ml）和心脏肌钙蛋白I水平（<0.4 ng/ml）正常的患者接受了受试者操作特征曲线分析，以确定肌红蛋白从0到90分钟升高的最佳切点。总体而言，75例患者（9%）被诊断为AMI，其中27例患者就诊时心脏肌钙蛋白I水平正常。在就诊时肌红蛋白或心脏肌钙蛋白I水平未升高的患者中，肌红蛋白从0到90分钟升高20 ng/ml具有最大诊断效用。在急诊科就诊时心脏肌钙蛋白I或肌红蛋白水平未升高的情况下，90分钟时肌红蛋白变化≥20 ng/ml对AMI的敏感性为83.3%，特异性为88.6%，阴性预测值为99.5%。心脏肌钙蛋白I和肌红蛋白水平以及90分钟内肌红蛋白变化≥20 ng/ml的综合敏感性为97.3%。在就诊时心脏肌钙蛋白I水平正常的急诊科患者中，肌红蛋白变化可在90分钟内对AMI进行高度准确的诊断。
