Gatzoulis K A, Carlson M D, Biblo L A, Rizos I, Gialafos J, Toutouzas P, Waldo A L
Department of Cardiology, Hippokration General Hospital, University of Athens, Greece.
Eur Heart J. 1995 Dec;16(12):1912-9. doi: 10.1093/oxfordjournals.eurheartj.a060847.
Doubts have been expressed about the clinical usefulness of time domain analysis of the signal averaged electrocardiogram in patients with prolonged QRS complex duration. We studied 147 patients using a signal averaged ECG (40-250 Hz) whose QRS complex was longer than 100 ms. A baseline electrophysiology study was also performed in 128 of these patients. Seventy-seven patients had a minor (QRS < 120 and > 100 ms) conduction defect. Thirty-seven of these 77 had either induced or spontaneous sustained ventricular tachycardia (group I) and 40 had no sustained ventricular tachycardia (group II). Seventy patients had a major (QRS > or = 120 ms) conduction defect, 44 of whom had sustained ventricular tachycardia (group A). The remaining 26 without this condition formed Group B. Group I compared to group II patients had a longer filtered QRS duration (120.8 +/- 14 vs 104.5 +/- 9.5 ms, P < 0.001), a longer low amplitude signal duration (41 +/- 12.1 vs 31 +/- 12.6 ms, P < 0.0001) and a lower root mean square of the last 40 ms of the filtered QRS complex (27 +/- 29.8 vs 35 +/- 25.3 microV, P = ns). Group A compared to group B had a longer filtered QRS duration (157.7 +/- 20.2 vs 140.7 +/- 15.7 ms, P < 0.001), a longer low amplitude signal duration (57.3 +/- 24.9 vs 37.8 +/- 20.3 ms P < 0.001) and a lower root mean square of the last 40 ms of the filtered QRS complex (14.3 +/- 11.2 vs 22.0 +/- 10.5 microV, P < 0.01). Using conventional late potential criteria, the sensitivity and specificity of the signal averaged ECG for the detection of sustained ventricular tachycardia patients with a minor conduction defect were 89% and 75%, respectively. The same criteria applied to patients with a major conduction defect were sensitive (sensitivity: 87%) but non-specific (specificity: 50%). However, by using modified late potential criteria, such as the presence of two of any of the following three signal averaged parameters: filtered QRS duration > or = 145 ms, low amplitude signal duration > or = 50 ms, root mean square of the last 40 ms of the filtered QRS complex < or = 17.5 microV, we derived a non-optimal but still acceptable combination of sensitivity (68%) and specificity (73%). We conclude that traditional late potential criteria can be applied in patients with a minor conduction defect, but modification of these criteria is necessary to derive useful clinical information for risk stratification of patients with a QRS complex duration > or = 120 ms.
对于QRS波群时限延长的患者，信号平均心电图的时域分析在临床中的实用性一直存在疑问。我们对147例QRS波群长于100ms的患者进行了信号平均心电图（40 - 250Hz）检查。其中128例患者还进行了基线电生理研究。77例患者存在轻度（QRS＜120且＞100ms）传导缺陷。这77例患者中，37例有诱发性或自发性持续性室性心动过速（I组），40例无持续性室性心动过速（II组）。70例患者存在重度（QRS≥120ms）传导缺陷，其中44例有持续性室性心动过速（A组）。其余26例无此情况的患者组成B组。与II组患者相比，I组患者的滤波后QRS时限更长（120.8±14对104.5±9.5ms，P＜0.001），低振幅信号时限更长（41±12.1对31±12.6ms，P＜0.0001），滤波后QRS波群最后40ms的均方根更低（27±29.8对35±25.3μV，P =无显著性差异）。与B组相比，A组患者的滤波后QRS时限更长（157.7±20.2对140.7±15.7ms，P＜0.001），低振幅信号时限更长（57.3±24.9对37.8±20.3ms，P＜0.001），滤波后QRS波群最后40ms的均方根更低（14.3±11.2对22.0±10.5μV，P＜0.01）。采用传统的晚电位标准，信号平均心电图检测轻度传导缺陷的持续性室性心动过速患者的敏感性和特异性分别为89%和75%。应用于重度传导缺陷患者的相同标准具有敏感性（敏感性：87%）但不具有特异性（特异性：50%）。然而，通过使用改良的晚电位标准，如以下三个信号平均参数中任意两个存在：滤波后QRS时限≥145ms、低振幅信号时限≥50ms、滤波后QRS波群最后40ms的均方根≤17.5μV，我们得出了一个虽非最佳但仍可接受的敏感性（68%）和特异性（73%）的组合。我们得出结论，传统的晚电位标准可应用于轻度传导缺陷的患者，但对于QRS波群时限≥120ms的患者进行风险分层时，有必要对这些标准进行修改以获得有用的临床信息。
