Pekdemir Murat, Karaca Ilgin, Cevik Yunsur, Yanturali Sedat, Ilkay Erdogan
Department of Emergency Medicine, Firat University, Elazig, Turkey.
Mt Sinai J Med. 2006 Sep;73(5):813-7.
Patients presenting with chest pain and nondiagnostic electrocardiograms (ECG) in the emergency department (ED) often pose a challenge to physicians. QT dispersion (QTD) is an electrocardiographic marker of myocardial ischemia due to nonhomogenous ventricular repolarization. We hypothesized that QTD could accurately identify patients with acute coronary syndrome (ACS) who presented with chest pain and nondiagnostic initial ECGs.
All patients admitted to the ED with chest pain and nondiagnostic initial ECGs were included in the study prospectively. QTD and QTc dispersion (QTcD) were measured at the initial ECGs and compared for ACS patients vs. non-ACS patients. A receiver operating characteristic curve was drawn to evaluate the diagnostic value of QTD and QTcD for ACS.
Of the 137 patients with an initially nondiagnostic ECG, 51 were finally diagnosed with ACS (37%). Mean QTD and QTcD of patients with ACS were significantly greater than those of patients without ACS (39.61 +/- 12.9 vs. 32.56 +/- 15.1, p=0.004; 46.12 +/- 16.3 vs. 38.10 +/- 18.2, p=0.009, respectively). The area under the curve was 0.624, p=0.015 for QTD, and 0.603 and p=0.049 for QTcD. When various cut-off points were evaluated, potentially useful values were determined between 30 and 50 ms for QTD (sensitivity 86% and 10%, specificity 35% and 97%, respectively). These values were 40.5 and 49.5 ms for QTcD (sensitivity was 96% and 32%, specificity was 12% and 77%, respectively).
For patients with chest pain and nondiagnostic initial ECG, ACS risk is high if QTD and QTcD values are greater than 40 ms. Therefore, QTD and QTcD can help identify patients with acute coronary syndrome who present with chest pain and a nondiagnostic initial ECG. However, poor operator characteristics of QT dispersion could limit its value as a diagnostic test in the clinical setting.
在急诊科（ED）出现胸痛且心电图（ECG）无诊断意义的患者常常给医生带来挑战。QT离散度（QTD）是由于心室复极不均一导致的心肌缺血的心电图标志物。我们假设QTD能够准确识别出因胸痛就诊且初始ECG无诊断意义的急性冠状动脉综合征（ACS）患者。
前瞻性纳入所有因胸痛就诊于ED且初始ECG无诊断意义的患者。在初始ECG上测量QTD和QTc离散度（QTcD），并比较ACS患者与非ACS患者的情况。绘制受试者工作特征曲线以评估QTD和QTcD对ACS的诊断价值。
在137例初始ECG无诊断意义的患者中，51例最终被诊断为ACS（37%）。ACS患者的平均QTD和QTcD显著高于非ACS患者（分别为39.61±12.9与32.56±15.1，p = 0.004；46.12±16.3与38.10±18.2，p = 0.009）。QTD的曲线下面积为0.624，p = 0.015；QTcD的曲线下面积为0.603，p = 0.049。当评估不同的截断点时，确定QTD在30至50毫秒之间可能具有有用的值（敏感性分别为86%和10%，特异性分别为35%和97%）。QTcD的这些值为40.5和49.5毫秒（敏感性分别为96%和32%，特异性分别为12%和77%）。
对于因胸痛就诊且初始ECG无诊断意义的患者，如果QTD和QTcD值大于40毫秒，则ACS风险较高。因此，QTD和QTcD有助于识别因胸痛就诊且初始ECG无诊断意义的急性冠状动脉综合征患者。然而，QT离散度较差的操作者特征可能会限制其在临床环境中作为诊断测试的价值。
