Detection of patients at risk for paroxysmal atrial fibrillation during sinus rhythm by P wave-triggered signal-averaged electrocardiogram

To determine whether patients at risk for paroxysmal atrial fibrillation could be detected while in sinus rhythm, the signal-averaged electrocardiogram triggered by P waves was recorded in 42 patients with paroxysmal atrial fibrillation (Paf group) and in 50 control patients. The root mean square voltages (LP10, LP20, and LP30) for the last 10, 20, and 30 msec and the duration (Ad) of filtered (40-300 Hz) P wave of the spatial magnitude were measured. LP10 and LP20 were significantly lower in the Paf than in the control group (LP10, 1.92 +/- 0.58 versus 2.49 +/- 0.78 microV, p less than 0.001; LP20, 2.47 +/- 0.78 versus 3.46 +/- 1.20 microV, p less than 0.0001), although no significant difference in LP30 was found between groups. Ad was also significantly longer in the Paf than in the control group (137.0 +/- 14.3 versus 118.6 +/- 11.3 msec, p less than 0.001). These differences between the Paf and control groups remained significant even after dividing by the presence or absence of organic heart diseases. The criteria of "LP20 = 3.5 microV or less" and "Ad greater than 120 msec" as defining "atrial late potential" gave a sensitivity of 91% and a specificity of 76%. These findings suggest that patients at risk for paroxysmal atrial fibrillation could be detected while in sinus rhythm by using the P wave-triggered signal-averaged electrocardiogram.     

Dispersion of signal-averaged P wave duration on precordial body surface in patients with paroxysmal atrial fibrillation.

AIMS: This study sought to investigate whether the spatial dispersion of signal-averaged P wave duration would be increased in patients with paroxysmal atrial fibrillation, by use of precordial mapping of the P wave signal-averaged ECG. METHODS AND RESULTS: The P wave signal-averaged ECG was recorded by the P wave-triggering method from 16 precordial leads in 55 patients with paroxysmal atrial fibrillation and 57 control subjects. As an index of the dispersion of signal-averaged P wave duration, we obtained the difference between the maximum and minimum in 16 recording sites. The dispersion was significantly greater in the patients with paroxysmal atrial fibrillation than the controls (26.6 +/- 9.5 vs 14.8 +/- 6.7 ms, P<0.0001). In 25 patients with symptomatic attacks of paroxysmal atrial fibrillation, the signal-averaged ECG was repeated 1 h after a single dose of orally administered pilsicainide, a new class Ic drug. These patients were prospectively followed-up for 10 +/- 11 months with pilsicainide. The rate of freedom from recurrence of paroxysmal atrial fibrillation attacks was significantly (P<0.0001) higher in patients with whom dispersion was decreased by the single dose (54%[7/13]) than in those in whom dispersion increased (8%[1/12]). CONCLUSION: Increased dispersion of signal-averaged P wave duration would play an important role in generating paroxysmal atrial fibrillation and would be useful in the prediction of drug efficacy to evaluate the change in dispersion by a single administration of pilsicainide.     

A "signal averaging" analysis of the P wave in patients with a history of isolated paroxysmal atrial fibrillation]

The aim of this study was to verify the utility of the signal averaged electrocardiogram for the analysis of the P wave in patients with paroxysmal lone atrial fibrillation. We studied 22 patients with documented paroxysmal atrial fibrillation without cardiovascular or endocrine diseases. The results were compared with 24 normal subjects. Signal averaged electrocardiogram was recorded from bipolar orthogonal leads X, Y, Z using ART equipment mod. 1200 EPX, with 50-250 Hz filter and effective time-base resolution of 100 mm/sec and voltage of 1 mm/microV. Signal averaging of at least 300 beats was performed to reduce noise level under 0.3 microV. In patients with atrial fibrillation the duration of the P wave was significantly longer (135.0 +/- 13.0 msec) than in the normal subjects (109.4 +/- 11.4 msec) (p less than 0.000001). These results were steady in successive recordings (2-30 days after the first recording). The analysis of the P wave signal averaging seems useful in identifying patients with lone paroxysmal atrial fibrillation.     

Risk for atrial fibrillation in patients with hypertrophic cardiomyopathy assessed by signal averaged P wave duration.

OBJECTIVE: To assess the relation between P wave duration and the occurrence of atrial fibrillation in hypertrophic cardiomyopathy (HCM). DESIGN: High resolution signal averaged electrocardiography was used in 110 patients with HCM to determine whether patients at risk for paroxysmal atrial fibrillation could be detected during sinus rhythm by measuring P wave duration. Filtered P wave duration was measured manually, over an average of 300 beats per patient. RESULTS: During follow up, 18 patients (16%) had at least one one clinical episode of paroxysmal atrial fibrillation, including four patients whose initial episode followed the signal averaged electrocardiogram. The 18 patients with overt atrial fibrillation had greater P wave duration than the 69 patients who did not develop atrial fibrillation: 150 (SD 20) v 126 (14) ms; P < 0.001. Another 23 patients without clinically evident atrial fibrillation had prolonged bursts of the arrhythmia on Holter recording, and showed a P wave duration (138 (15) ms) intermediate between patients with and without clinical atrial fibrillation. In assessing risk for atrial fibrillation, P wave duration > or = 140 ms was associated with sensitivity, specificity, and positive predictive accuracy values of 56%, 83%, and 66%. Multivariate analysis showed that duration of the P wave was the only independent variable associated with occurrence of atrial fibrillation; if P wave duration > or = 140 ms was combined with left atrial enlargement > 40 mm, the specificity and positive predictive accuracy for atrial fibrillation increased to 93% and 78%. CONCLUSIONS: Measurement of P wave duration in sinus rhythm by high resolution signal averaged electrocardiography may be a useful non-invasive clinical tool for identifying patients with HCM likely to develop electrical instability and atrial fibrillation.     

Characteristics of frequency content of atrial signal-averaged electrocardiograms during sinus rhythm in patients with paroxysmal atrial fibrillation.

To clarify the characteristics of the frequency content of atrial signal-averaged electrocardiograms (ECGs) during sinus rhythm in patients with paroxysmal atrial fibrillation, P wave-triggered signal-averaged ECGs were recorded in 28 patients with and 34 control patients without paroxysmal atrial fibrillation. Fast Fourier transform analysis was performed on the 100-ms segment starting 75 ms before the end of the P wave. An area ratio (AR50) was calculated by dividing the area under the spectrum curve between 20 and 50 Hz, multiplied by 100, by the area between 0 and 20 Hz. Magnitude ratios (MR20, MR30, MR40 and MR50) were calculated by dividing the magnitude at 20, 30, 40 and 50 Hz, respectively, multiplied by 100, by the maximal magnitude of the entire signal. AR50 was significantly greater in patients with than without paroxysmal atrial fibrillation (62.3 +/- 34.2 vs. 42.4 +/- 18.4). MR20 and MR30 were also significantly greater in patients with than without paroxysmal atrial fibrillation (MR20 76.1 +/- 15.2 vs. 60 +/- 20.2; MR30 41 +/- 18.8 vs. 26.6 +/- 14.4), although no significant differences in MR40 or MR50 were observed between the two patient groups. The difference in MR30 between groups remained significant even after taking into account the presence of organic heart disease. It is concluded that, irrespective of the presence of organic heart disease, the terminal portion of the P wave contained significantly more components in the 20- to 50-Hz range, especially around 30 Hz, in patients with than in patients without paroxysmal atrial fibrillation. These results suggest that frequency analysis could characterize atrial signal-averaged ECGs of patients at risk for paroxysmal atrial fibrillation.     

Prediction of atrial fibrillation recurrence after cardioversion by P wave signal-averaged electrocardiography.

The purpose of this report was to determine prospectively whether P wave signal-averaged electrocardiography (ECG) is useful for the prediction of recurrences of atrial fibrillation after cardioversion. The P wave signal-averaged ECG was recorded in 73 patients after successful cardioversion. Duration of the filtered P wave and the root mean square voltages for the last 20 ms of the P wave were calculated. In addition to signal-averaged ECG P wave analysis, all patients were evaluated by echocardiography. During 6 months follow-up period recurrence of atrial fibrillation was observed in 31 (42.5%) patients and in 42 (57.5%) patients sinus rhythm was maintained. There was no difference in gender, age, presence of organic heart disease, left atrial diameter, left ventricular ejection fraction, use of antiarrhythmic drug, and duration of atrial fibrillation (P>0.05). The filtered P-wave duration was longer and the root mean square voltages for the last 20 ms of the P wave was lower in patients with recurrence of atrial fibrillation than in patients who maintained sinus rhythm (138.3+/-12.5 ms vs. 112.4+/-11.8 ms, P = 0.001; 1.9+/-0.7 microV vs. 2.5+/-0.6 microV, P = 0.001). A filtered P-wave duration > or =128 ms associated with a root mean square voltage for the last 20 ms of the P wave < or =2.1 microV had a sensitivity of 70% and specificity of 76% for the detection of patients with recurrence of atrial fibrillation after successful cardioversion of atrial fibrillation. We found that the likelihood of recurrence of atrial fibrillation after cardioversion was increased 4.31-fold (95% confidence interval 2.08-9.83) if these parameters were used. These results suggest that P wave signal-averaged ECG could be useful to identify patients at risk for recurrence of atrial fibrillation after cardioversion.     

Assessment of right artrial mapping and P wave-triggered signal-average in patients with paroxysmal atrial fibrillation.

To assess right atrial mapping and P wave-triggered signal-averaged electrocardiogram (ECG) in patients with paroxysmal atrial fibrillation (PAF), this study examined right atrial electrograms using atrial mapping and parameters by P wave-triggered signal-averaged ECG in 39 patients without sick sinus syndrome. Subjects were divided into those with PAF (n = 13; 60+/-13 years old) and a control group (n = 26; 49+/-19 years old). The total number of abnormal right atrial electrograms per patient was significantly greater in the PAF group (3.2+/-1.9) than in the control group (1.1+/-0.9; P < .001). The longest duration of right atrial electrogram in the PAF group tended to be greater than that in the control group (P = .06). The filtered P wave duration was significantly longer in the PAF group than in the control group (144+/-21 vs 125+/-14 ms [P < .002]). The values of the root mean square of P wave-triggered signal-averaged ECG 15 ms from the onset (RMSi 15) and 20 ms from the offset (RMSe 20) were significantly lower in the PAF group (1.1+/-0.4 microV, 1.4+/-0.5 microV) than in the control group (1.9+/-1.1 microV [P < .02], 2.1+/-0.9 microV [P < .01]). The total number of right atrial electrograms in patients with RMSi 15 of < or =1.5 microV was significantly greater than in patients with RMSi 15 of >1.5 microV (2.2+/-1.8 vs 1.3+/-1.3 [P < .05]). Thus, the total number of abnormal right atrial electrograms per patient, the total filtered P wave duration, RMSi 15, and RMSe 20 may be good indices of PAF in patients without sick sinus syndrome. RMSi 15 may reflect the total number of the abnormal right atrial electrograms per patient.     

左房异常与心房颤动的关系

目的探讨左房异常与心房颤动发生的关系。方法应用心电图和动态心电图进行,持续性房颤患者为A组,阵发性房颤、房扑患者为B组,仅有心电图P波增宽的患者为C组,A、B、C三组各40例。所有入选患者均经超声心动图检测左房大小,观察患者窦性心律时心电图P波时限、切迹和P波离散度,并分析与房颤发生的关系。结果房颤男性多于女性,年龄大于60岁者94例(占78.3%),三组中86.7%的患者存在器质性心脏病(104例)。心电图P波切迹明显、P波离散度大者快速房颤发生率高;超声心动图检测左房直径大者房颤发生率高,持续性房颤比阵发性房颤患者左房直径大(p<0.05)。结论左房扩大、房内阻滞及P波离散度增大的患者易发生房颤。     

阵发性心房颤动预测因素研究

目的　研究阵发性心房颤动 (PAF)的预测因素。方法　 PAF组 5 9例 ,对照组 31例。同步记录 12导联心电图 ,测量 P波离散度 (Pdis)、P波最大时限 (Pm ax) ;应用超声心动图测量左心房内径 ,计算左室心肌重量指数。结果　与对照组比较 ,PAF组 Pmax、Pdis、左房内径显著增大 (P<0 .0 1) ;Pmax与左房内径和左室心肌重量指数呈正相关 (r =0 .2 6 ,P <0 .0 5 ;r =0 .2 7,P <0 .0 5 ) ;结论　左房内径和 Pm ax为 PAF的独立预测指标 ,P波宽度与左房内径扩大和左室心肌重量指数增加有关。     

Atrial electrophysiological abnormality in patients with Brugada syndrome assessed by P-wave signal-averaged ECG and programmed atrial stimulation.

BACKGROUND: There is evidence that some patients with Brugada syndrome (BS) exhibit atrial tachyarrhythmias including paroxysmal atrial fibrillation. We investigated whether BS associated not only with vulnerability to ventricular fibrillation, but also with vulnerability to atrial fibrillation. METHODS AND RESULTS: In 15 patients with BS and Brugada-type electrocardiogram (ECG) (14 men, 1 woman; age 52.8+/-12.9 years) and 15 age-matched control patients (12 men, 3 women; age 50.9+/-18.9 years), the P-wave signal-averaged ECG was recorded, and the filtered P-wave duration was derived from the vector magnitude obtained by X, Y, Z leads. In 11 of the 15 patients with BS and Brugada-type ECG, invasive electrophysiologic testing was conducted. Filtered P-wave duration was significantly increased in patients with BS and Brugada-type ECG in comparison with control subjects (143.2+/-12.9 vs 129.6+/-10.1 ms, p<0.001). Ventricular late potential (root mean square voltage <20 muV in the last 40 ms and <40 muV at a low amplitude signal duration >38 ms) was present in 10 of the 12 BS patients in whom a QRS wave signal-averaged electrogram was also recorded. In all 11 patients with Brugada-type ECG who underwent electrophysiologic testing, sustained atrial fibrillation (>5 min) was induced by 1 or 2 atrial extrastimuli. In 10 of these 11 patients, ventricular fibrillation was also induced by 2 or 3 right ventricular extrastimuli. CONCLUSIONS: The electrical abnormality in BS is not limited to the ventricular level; similar changes occur in the atria. Such abnormal conduction properties could be a substrate for re-entrant atrial tachyarrhythmias.     

P波最大时间及离散度预测特发性心房颤动的价值

为探讨Ｐ波最大时间及其离散度对特发性心房颤动的预测价值,观察２０例特发性心房颤动患者及２０例健康者１２导联同步体表心电图Ｐ波最大时间及离散度。结果显示：特发性心房颤动组Ｐ波最大时间及离散度均较对照组增大（Ｐ〈０．０１）,Ｐ波最大时间〉１１０ｍｓ、Ｐ波离散度〉４０ｍｓ以及两者相结合对特发性心房颤动预测的敏感性分析为９０＾、８５％、７５％,特异性分别为８０％、８５％和９０％。提示这两项指标可用于预测特     

Electrophysiologic study of cibenzoline in patients with paroxysmal atrial fibrillation with special reference to atrial fibrillation threshold]

Electrophysiologic effects of cibenzoline were studied in 7 patients (6 males and one female) aged from 40 to 69 years (mean +/- SD; 52 +/- 10) with paroxysmal atrial fibrillation which was documented by 12 leads ECG or by 24 hours Holter monitoring. No organic heart diseases were found except in one patient with dilated cardiomyopathy and sick sinus syndrome (SSS). Cibenzoline (200mg) given orally increased P wave duration, PR interval and QRS duration significantly. The duration of P wave was gradually increased as the pacing frequency was increased. Neither sinus cycle length, nor sinus node recovery time (SRT), nor Wenkebach cycle length, nor atrial effective refractory period, nor QT interval was changed by the drug. One patient with SSS showed increase in SRT from 2,303 msec to 5,150 msec. The minimum current which was required to induce atrial fibrillation by rapid atrial stimulation (50 Hz, 1 sec) lasting more than 30 sec was defined as atrial fibrillation threshold (AFT). The AFT was 4.0 +/- 2.2 mA at the baseline state in 7 patients. After the oral administration of cibenzoline, 5 patients showed increase in AFT, while 1 patient showed decrease and another patient showed no change in AFT. Statistically, AFT was significantly increased to 7.3 +/- 3.4 mA in 7 patients. The results suggest that cibenzoline might be effective to prevent paroxysmal atrial fibrillation in patients without organic heart diseases.     

P wave signal-averaged electrocardiogram as a new marker for atrial tachyarrhythmias in postoperative Fontan patients

OBJECTIVES: This study was undertaken to determine the potential role of P wave signal-averaged electrocardiogram (PSAECG) for risk assessment of atrial tachyarrhythmias (ATs) in patients after Fontan operation. BACKGROUND: Onset of atrial flutter/fibrillation (AFF) in patients who have undergone Fontan operation for univentricular hearts constitutes an unfavorable clinical event associated with a high risk of cardiovascular complications. There is no data available on PSAECG in postoperative Fontan patients to predict potential susceptibility to ATs. METHODS: Twenty-four post-Fontan patients and 15 age-matched healthy subjects were prospectively studied with PSAECG, and the following measurements were made: filtered P wave duration (FPWD), P wave vector integrals (PINTs), root-mean-square voltage for the initial 30 ms (RMSi30), and duration of persistent amplitude signals <4 microV from the beginning of the P wave (Di4). RESULTS: The FPWDs were significantly longer in the study group patients with ATs when compared with the study group patients without ATs (p<0.01) and compared with the controls (p < 0.001). An FPWD cut point of 135 ms resulted in a sensitivity of 71% and a specificity of 81% in differentiating patients with ATs from patients without ATs among the postoperative Fontan patients. The PINT was significantly greater in Fontan patients with AFF and also without AFF when compared with controls (p<0.01, p<0.05, respectively). The RMSi30 and the Di4 were not significantly different between study and control groups. CONCLUSIONS: Signal-averaged P wave duration is significantly prolonged in postoperative Fontan patients. A prolonged signal-averaged P wave duration may be an effective noninvasive marker to predict risk of development of ATs in this patient group.     

The effects of atrial pacing on the signal-averaged electrocardiogram in patients with coronary artery disease

The effects of atrial pacing on the signal-averaged electrocardiogram were studied in 14 patients with remote myocardial infarction and a history of cardiac arrest or sustained ventricular tachycardia (group I) and in 13 patients with coronary artery disease and no history of sustained ventricular tachyarrhythmia (group II). Recordings of the signal-averaged electrocardiogram were obtained at control and during atrial pacing at rates of 80, 100, and 120 beats/min. All patients had recordings analyzed from at least two paced rates. At control, the mean high frequency total duration of the QRS complex (HFTD) was significantly longer in group I versus group II patients (123 +/- 5.6 versus 111 +/- 3.5 msec, p less than 0.05). Although the duration of the QRS signal under 40 microV (D40) was higher in group I versus group II patients (42 +/- 4.7 versus 32.4 +/- 3.5 msec) and the root mean square amplitude of the terminal 40 msec QRS (RMSA) was lower in the group I patients (27 +/- 7.5 versus 38.1 +/- 8.8 microV), these differences did not achieve statistical significance. There was no effect of atrial pacing on the measured signal-averaged parameters of HFTD, D40, and RMSA. Although there was a difference between group I and group II at each paced rate analyzed, atrial pacing did not help to further stratify the groups. In patients with coronary artery disease, atrial pacing is not a useful method of stratifying high-risk patients. Changes in serial signal-averaged electrocardiograms from the same patient are not due to heart rate variability.     

Effects of amiodarone on the P-wave triggered signal-averaged electrocardiogram in patients with paroxysmal atrial fibrillation and coronary artery disease

The effects of a 6-week treatment with amiodarone on the P-wave triggered signal-averaged electrocardiogram in patients with paroxysmal atrial fibrillation and coronary artery disease have been studied. Amiodarone favorably influences P-wave triggered signal-averaged electrocardiographic parameters, predominantly in patients in whom amiodarone is effective in preventing paroxysmal atrial fibrillation.     

P wave signal-averaged electrocardiography predicts recurrence of paroxysmal atrial fibrillation in patients with Wolff-Parkinson-White syndrome who underwent successful catheter ablation: a prospective study

INTRODUCTION: Paroxysmal atrial fibrillation (PAF) frequently occurs in patients with Wolff-Parkinson-White (WPW) syndrome. Catheter ablation of the accessory pathway eliminates PAF in some patients, but PAF frequently recurs in other patients. The present study was designed to determine prospectively whether P wave signal-averaged electrocardiography (P-SAECG) predicts the recurrence of PAF after successful ablation in patients with WPW syndrome. METHODS AND RESULTS: Forty-six patients with WPW syndrome who had episodes of PAF were prospectively followed. SAECG recording was performed on day 7 after successful ablation of the accessory pathway at study entry. Abnormal P-SAECG for the prediction of recurrence of PAF was defined as a filtered P wave duration > 130 msec. Eleven patients had an abnormal P-SAECG (group 1), whereas 35 patients (group 2) did not. The two groups did not differ in terms of gender, age, left atrial dimension, and atrial vulnerability as determined by electrophysiologic study. During follow-up (40 +/- 19 months), the recurrence of PAF was noted in 10 (91%) of 11 patients in group 1, whereas it was observed in only 2 (6%) of 35 patients in group 2. Kaplan-Meier analysis revealed that the recurrence of PAF was significantly more frequent in group 1 than in group 2 (log rank test, P < 0.0001). By multivariate analysis, filtered P wave duration >130 msec was an independent predictor of recurrence of PAF after ablation (Chi-square = 21.5, P < 0.0001). CONCLUSION: The results of this study indicate that P-SAECG may be useful for identifying patients at risk for recurrence of PAF after successful ablation of WPW syndrome.     

Reduction of P-wave duration and successful pulmonary vein isolation in patients with atrial fibrillation

Introduction: We hypothesize that successful pulmonary vein (PV) isolation can shorten the P-wave duration in patients with atrial fibrillation (AF).
Methods and Results: We recorded magnified surface electrocardiogram (ECG) and P-wave signal-averaged ECG using 12 electrode leads before and after 31 PV isolation procedures in 27 patients with AF. The patients were followed for 16 ± 4 months. Repeat ablation studies documented failed PV isolation in seven patients with AF recurrences. At baseline, the maximal P-wave duration in patients without AF recurrence (161 ± 7 msec) was slightly shorter than that in patients with AF recurrence (168 ± 10 msec, P < 0.05). After ablation, patients without recurrence showed a significant reduction of P-wave duration from 161 ± 7 msec to 151 ± 8 msec (P < 0.0001). In contrast, no change of P-wave duration was noted in patients with recurrences. These findings were confirmed with signal averaged ECG of the P-waves. Three-dimensional (3-D) computer simulation using an atrial cell model showed that elimination of the muscle sleeves inside the PV resulted in a shortening of the P-wave duration and change of the terminal portion of the P-wave morphology.
Conclusions: A significant shortening of P-wave duration by P-wave signal-averaged ECG can be used as an indicator for successful PV isolation. These findings suggest that activation of the PV muscle sleeves may be an important component of the terminal portion of the P-wave on surface ECG.     

不同部位起搏对阵发性心房颤动患者心房激动时间的影响

目的　比较右心耳 (RAA)、冠状窦远端 (DCS)、右心房双部位 (右心耳加冠状窦口 ,DSA)和双房 (右心耳加冠状窦远端 ,Bi A)起搏对阵发性心房颤动 (PAf)患者心房激动时间的影响。方法 2 2例接受心脏电生理评价试验的PAf患者在窦性心律下行心房不同部位起搏 ,同步记录 12导心电图 ,测量最大 P波时限。结果　与窦性 P波时限相比 ,RAA起搏明显延长 P波时限 (P<0 .0 1) ,DCS、DSA及 Bi A起搏则明显缩短 P波时限 (P<0 .0 1,P<0 .0 1,P<0 .0 1)。结论　 DCS、DSA及 Bi A起搏明显缩短心房激动时间 ,减少心房电活动的离散度 ,有利于 PAf的防治。     

P波离散度与阵发性心房颤动的关系研究

目的 探讨体表心电图P波离散度（P-wave dispersion,Pdis）对阵发性心房颤动的预测价值。方法 对86例阵发性心房颤动病人（观察组）和同期54例健康成人（对照组）窦性心律时体表心电图的Pdis、P波最大时限（maximum P-wave duration，Pmax）进行测量分析。结果 观察组Pdis和Pmax与对照组比较,差异有统计学意义（P＜0.01）,Pdis或Pdis加Pmax对阵发性心房颤动有较高的特异度（81.5%,92.6%）和阳性预测价值（88.2%,94.6%）。结论 Pdis可作为预测阵发性心房颤动的一个可靠的体表心电图指标。