Ho D S, Denniss R A, Uther J B, Ross D L, Richards D A
Cardiology Unit, Westmead Hospital, Australia.
Circulation. 1993 Mar;87(3):857-65. doi: 10.1161/01.cir.87.3.857.
Although the signal-averaged ECG (SAECG) is currently the best noninvasive test to identify patients with ventricular tachycardia (VT) following myocardial infarction (MI), it is still a relatively insensitive test. Body surface mapping has improved the sensitivity of ECG in detecting various cardiac diseases. This study applied body surface mapping to the SAECG in the form of a clinically practical, 28-lead optimal array and compared its sensitivity and specificity with those of an orthogonal array.
Two hundred twenty-three patients with previous MI (82 with inducible VT) underwent SAECG using 28 surface electrodes from which were obtained a three-lead orthogonal array and a 28-lead optimal array (optimal). From the orthogonal array, two QRS durations (QRSd) were obtained using the combined vector magnitude method (CVM) and the earliest onset to latest offset of the three individually filtered leads (individual). From the optimal array, 28 QRSd were obtained, each defined as the duration from the earliest onset of any of the 28 leads to the offset of each individually filtered lead. QRSd > 120 msec in > or = 3 leads was considered abnormal. For CVM and individual, QRSd of > 120 msec were considered abnormal. While the specificity of each method was comparable (84%, 86%, and 84% for CVM, individual, and optimal, respectively), the sensitivity of optimal (70%) was significantly greater than the sensitivity of CVM (54%) (p = 0.001) or individual (59%) (p = 0.004). The magnitude of improvement in sensitivity, 16% and 15%, respectively, was equal for anterior (n = 120) and inferior (n = 103) infarctions.
Body surface mapping using the 28-lead optimal array significantly improved the sensitivity of the SAECG without loss of specificity. The increased sensitivity was of equal magnitude for inferior and anterior infarctions. The superiority and practicality of the 28-lead optimal array make it worth pursuing as an option for further refinement in SAECG:
虽然信号平均心电图（SAECG）是目前识别心肌梗死（MI）后室性心动过速（VT）患者的最佳无创检查，但它仍然是一种相对不敏感的检查。体表标测提高了心电图检测各种心脏疾病的敏感性。本研究将体表标测以临床实用的28导联最佳阵列形式应用于SAECG，并将其敏感性和特异性与正交阵列进行比较。
223例既往有心肌梗死的患者（82例可诱发出室性心动过速）使用28个表面电极进行SAECG检查，从中获得一个三导联正交阵列和一个28导联最佳阵列（最佳阵列）。从正交阵列中，使用组合向量幅值法（CVM）以及三个单独滤波导联的最早起始至最晚结束来获得两个QRS波时限（QRSd）（单独导联法）。从最佳阵列中，获得28个QRSd，每个定义为28个导联中任何一个的最早起始至每个单独滤波导联结束的时限。≥3个导联的QRSd>120毫秒被认为异常。对于CVM和单独导联法，QRSd>120毫秒被认为异常。虽然每种方法的特异性相当（CVM、单独导联法和最佳阵列法分别为84%、86%和84%），但最佳阵列法的敏感性（70%）显著高于CVM法（54%）（p=0.001）或单独导联法（59%）（p=0.004）。前壁梗死（n=120）和下壁梗死（n=103）敏感性提高的幅度分别为16%和15%，二者相同。
使用28导联最佳阵列的体表标测显著提高了SAECG的敏感性，且不损失特异性。下壁梗死和前壁梗死的敏感性提高幅度相同。28导联最佳阵列的优越性和实用性使其值得作为进一步优化SAECG的一种选择加以探索。
