Caref E B, Turitto G, Ibrahim B B, Henkin R, el-Sherif N
Department of Medicine, State University of New York Health Science Center, Brooklyn 11203.
Am J Cardiol. 1989 Jul 1;64(1):16-26. doi: 10.1016/0002-9149(89)90646-2.
Normal values for the signal-averaged electrocardiogram (SAECG) at 11 different high-pass filter settings were obtained from 100 normal subjects (group I). The filtered QRS duration and the duration of low amplitude signals less than 40 microV, but not the root mean square voltage of the last 40 ms (RMS40), showed normal distribution. A normal distribution for RMS40 could be obtained by transforming each value to its natural logarithm. The normal values were used in a systematic approach to optimize the accuracy of the SAECG to predict the results of programmed stimulation in 80 patients with spontaneous nonsustained ventricular tachycardia (VT). Fifty-two patients with no inducible VT (group II) and 28 patients with inducible sustained monomorphic VT (group III) were investigated. The 3 SAECG parameters at each high-pass filter in groups II and III were categorized as normal or abnormal and were evaluated singly or in combinations of 2 or 3. There was no combination that provided a sensitivity greater than 82% that could also be obtained by single determinations of low amplitude signals less than 40 microV at 25 to 40 Hz or RMS40 at 40 Hz. On the other hand, there were 267 different combinations that provided a maximal specificity of 98%. The best total predictive accuracy of a single parameter was 85%, provided by RMS40 at 40 or 60 Hz. The total predictive accuracy could be improved to 89% by 1 of 32 different combinations. The top combinations were mostly in triplets and included SAECG parameters recorded at different high-pass filter settings. The only 2 paired combinations with the best total predictive accuracy were RMS40 at 20 or 25 Hz paired with RMS40 at 40 Hz. Frequencies at both ends of the analyzed high-pass filter settings (less than 20 Hz and greater than 60 Hz) were not represented in the top predictive combinations. The SAECG parameters analyzed at 40 Hz were most frequently represented in the top predictive combinations, suggesting that the SAECG may have the best predictive accuracy at this filter setting. In summary, the combination of SAECG parameters analyzed at different filter settings can enhance the accuracy of the technique as a screening test for the results of programmed stimulation in patients with spontaneous nonsustained VT.
从100名正常受试者（第一组）中获取了11种不同高通滤波器设置下信号平均心电图（SAECG）的正常值。滤波后的QRS波时限以及小于40微伏的低振幅信号的时限呈正态分布，但最后40毫秒的均方根电压（RMS40）不呈正态分布。通过将每个值转换为其自然对数可使RMS40呈正态分布。这些正常值被用于一种系统方法中，以优化SAECG预测80例自发性非持续性室性心动过速（VT）患者程控刺激结果的准确性。对52例无诱发性VT的患者（第二组）和28例有诱发性持续性单形性VT的患者（第三组）进行了研究。将第二组和第三组中每个高通滤波器设置下的3个SAECG参数分类为正常或异常，并单独或进行二联或三联组合评估。没有一种组合的敏感性高于82%，而通过在25至40赫兹时单独测定小于40微伏的低振幅信号或在40赫兹时单独测定RMS40也能获得这样的敏感性。另一方面，有267种不同组合的最大特异性为98%。单个参数的最佳总预测准确性为85%，由40或60赫兹时的RMS40提供。通过32种不同组合中的一种，总预测准确性可提高到89%。最佳组合大多为三联组合，包括在不同高通滤波器设置下记录的SAECG参数。唯一两种总预测准确性最佳的二联组合是20或25赫兹时的RMS40与40赫兹时的RMS40配对。分析的高通滤波器设置两端的频率（小于20赫兹和大于60赫兹）未出现在最佳预测组合中。在最佳预测组合中，40赫兹时分析的SAECG参数出现频率最高，这表明在该滤波器设置下SAECG可能具有最佳预测准确性。总之，不同滤波器设置下分析的SAECG参数组合可提高该技术作为自发性非持续性VT患者程控刺激结果筛查试验的准确性。
