Guidera S A, Steinberg J S
Division of Cardiology, Columbia-Presbyterian Medical Center, New York, New York.
J Am Coll Cardiol. 1993 Jun;21(7):1645-51. doi: 10.1016/0735-1097(93)90381-a.
This study was undertaken to determine the ability of the signal-averaged electrocardiogram (ECG) to identify evidence of delayed atrial activation in patients with a history of atrial fibrillation.
Atrial fibrillation is a reentrant rhythm and depends on atrial conduction delay for its development. The signal-averaging technique is useful for accurately measuring total cardiac activation times, including delayed low amplitude signals, and thus can help identify the substrate for reentrant arrhythmias.
Standard 12-lead and signal-averaged ECGs were recorded from 15 patients with a documented history of prior paroxysmal or chronic atrial fibrillation and 15 age- and disease-matched control subjects without a history of atrial fibrillation. Signal averaging was performed using an orthogonal lead system with the QRS complex as a trigger and the P wave as a template for the signal-averaging process. Total P wave duration was measured before and after filtering with a least squares fit filter. The P wave complexes on the three bipolar leads were combined into a vector combination of orthogonal leads. The total P wave duration of the individual unfiltered and filtered leads and the vector combination of filtered leads were calculated and used for analysis.
The P wave duration by standard ECG was not significantly different in patients with a history of atrial fibrillation and control subjects. Signal-averaged P wave durations were measured from orthogonal leads before and after digital filtering. Mean unfiltered P wave duration was significantly longer in patients with a history of atrial fibrillation than in control subjects (132 +/- 22 vs. 114 +/- 14 ms [p < 0.03] in the X lead, 135 +/- 21 vs. 115 +/- 15 ms [p < 0.03] in the Y lead and 133 +/- 23 vs. 114 +/- 14 ms [p < 0.03] in the Z lead). Mean filtered P wave duration was also longer in patients with atrial fibrillation than in control subjects (151 +/- 23 vs. 130 +/- 19 ms [p < 0.01] in the X lead, 157 +/- 22 vs. 136 +/- 17 ms [p < 0.01] in the Y lead and 154 +/- 23 vs. 135 +/- 15 ms [p < 0.01] in the Z lead). After filtering, a vector composite of orthogonal leads was determined. Again, P wave duration in patients with a history of atrial fibrillation exceeded that in the control subjects (162 +/- 15 vs. 140 +/- 12 ms [p < 0.01]). Using the vector composite of filtered orthogonal leads, a P wave duration > or = 155 ms was associated with a sensitivity of 80%, a specificity of 93% and a positive predictive value of 92% for identifying patients with history of atrial fibrillation.
A prolonged signal-averaged P wave duration may be a simple noninvasive marker of the risk for development of atrial fibrillation.
本研究旨在确定信号平均心电图（ECG）识别有房颤病史患者心房激动延迟证据的能力。
房颤是一种折返性心律，其发生依赖于心房传导延迟。信号平均技术有助于准确测量总的心脏激动时间，包括延迟的低振幅信号，因此可帮助识别折返性心律失常的基质。
记录了15例有阵发性或慢性房颤病史的患者以及15例年龄和疾病匹配、无房颤病史的对照者的标准12导联和信号平均ECG。使用以QRS波群为触发、P波为信号平均过程模板的正交导联系统进行信号平均。在使用最小二乘拟合滤波器滤波前后测量总P波持续时间。将三个双极导联上的P波复合波合并为正交导联的向量组合。计算并分析单个未滤波和滤波导联以及滤波导联向量组合的总P波持续时间。
有房颤病史的患者与对照者的标准ECG测量的P波持续时间无显著差异。在数字滤波前后从正交导联测量信号平均P波持续时间。有房颤病史的患者未滤波的平均P波持续时间显著长于对照者（X导联：132±22 vs. 114±14 ms [p<0.03]，Y导联：135±21 vs. 115±15 ms [p<0.03]，Z导联：133±23 vs. 114±14 ms [p<0.03]）。房颤患者滤波后的平均P波持续时间也长于对照者（X导联：151±23 vs. 130±19 ms [p<0.01]，Y导联：157±22 vs. 136±17 ms [p<0.01]，Z导联：154±23 vs. 135±15 ms [p<0.01]）。滤波后，确定了正交导联的向量复合波。同样，有房颤病史患者的P波持续时间超过对照者（162±15 vs. 140±12 ms [p<0.01]）。使用滤波后的正交导联向量复合波，P波持续时间≥ 155 ms识别有房颤病史患者的敏感性为80%，特异性为93%，阳性预测值为92%。
信号平均P波持续时间延长可能是房颤发生风险的一个简单无创标志物。
