Filtered P-wave Duration Research Articles

Relationship between electrical conduction and phasic left atrial function: P-wave signal-averaged electrocardiography and time-left atrial volume curve assessments using two-dimensional speckle-tracking echocardiography.

P-wave signal-averaged electrocardiography (P-SAECG) can detect imperceptible conduction abnormalities, and volume analysis using two-dimensional speckle-tracking echocardiography (2-DSTE) allows us to easily measure the phasic function of the left atrium (LA). Both conduction abnormalities and functional deformation of the LA may be linked to the clinical outcome; however, the exact relationship is unclear. The aim of this study was to investigate the relationship between the phasic function of the LA and electrical conduction using P-SAECG and 2-DSTE. The subjects were 112 male volunteers (age 46.9 ± 13.2years) with normal cardiac function who underwent P-SAECG and 2-DSTE. The filtered p-wave duration (FPD) and the root-mean-square voltage for the last 20ms (RMS20) on P-SAECG wave were measured in ms and μV, respectively. Total emptying function (EF) (reservoir function), passive EF (conduit function), and active EF (booster pump function) of the LA were calculated as percentages to evaluate phasic LA function using 2DSTE. The mean FPD was 134.3 ± 11.7ms and the mean RMS20 was 4.59 ± 2.39μV. The mean total EF was 60.5 ± 13.1%, mean passive EF was 39.4 ± 13.9%, and mean active EF was 35.1 ± 13.9%. FPD had a negative correlation with passive EF (r=-0.20, p = 0.039). FPD showed no significant relationship with total EF (r=-0.03, p = 0.78) or active EF (r = 0.13, p = 0.18). There was a significant association between RMS20 and passive EF (r = 0.19, p = 0.048); however, no there was no correlation between RMS20 and total EF (r = 0.12, p = 0.23), or between RMS20 and passive EF (r=-0.02, p = 0.86). In multivariate regression analysis, passive EF was an independent factor that influenced FPD duration. This study indicated that FPD was associated with conduit function, which includes phasic LA function. Therefore, electrical conduction of the LA and left ventricular diastolic function are closely related. In the clinical setting, when conduction abnormalities are detected, lifestyle measures or interventions can be applied to reduce cardiovascular risk.

An ECG Index of P-Wave Force Predicts the Recurrence of Atrial Fibrillation after Pulmonary Vein Isolation.

Although several prognostic factors of atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) have been investigated, the accurate prediction of AF recurrence remains difficult. We propose an electrocardiogram (ECG) index, the P-wave force (PWF), which is the product of the amplitude of the negative terminal phase of the P wave in the V1 electrode and the filtered P-wave duration, obtained by a signal-averaged P-wave analysis. This study was conducted to evaluate the impact of the PWF on the recurrence of AF after PVI. We retrospectively evaluated 79 paroxysmal AF patients (64 ± 9 years, 56 males) who underwent PVI by cryoballoon ablation. Standard 12-lead ECG and a P-wave signal-averaged electrocardiogram (SAECG) were recorded the day before and 1 month after the PVI procedure. During the mean follow-up of 10.2 months, AF recurred in 11 (14%) patients. The PWF 1 month after ablation was significantly higher in the recurrence group compared to that in the nonrecurrence group (8.8 ± 3.1 mVms vs 6.5 ± 2.9 mVms, P = 0.017). The patients with a PWF value ≥9.3 mVms had a significantly greater risk of recurrence after the ablation compared to the patients with a PWF value <9.3 mVms (log-rank test, P < 0.001). Higher PWF after cryoballoon ablation was associated with poor prognosis during follow-up. The PWF may be a useful and noninvasive marker to predict the recurrence of AF.

The impact of left atrial pressure on filtered P-wave duration in patients with atrial fibrillation.

The cause of prolonged filtered P-wave duration (FPD) remains unclear in atrial fibrillation (AF) patients with normal left atrial size. We investigated whether FPD is associated with left atrial pressure (LAP) in AF patients without prominent LA enlargement. This study included 80 patients (48 men, age 65±9years, 25 persistent AF) with non-valvular AF who underwent catheter ablation (CA) for AF. LAP was measured in sinus rhythm during CA and signal-averaged electrocardiogram was recorded after CA. We retrospectively assessed the clinical and echocardiographic variables. Prolonged FPD was defined as FPD>120ms. Prolonged FPD (FPD>120ms) was detected in 23/80 patients (29%). According to univariate analysis, higher mean LAP (14.9±4.4 vs. 10.8±3.5mmHg, p<0.0001), higher prevalence of persistent arrhythmia, higher BNP, larger LAD, higher E wave, and lower LVEF were associated with Prolonged FPD. According to multivariate analysis, higher mean LAP was the only factor associated with Prolonged FPD (p=0.0058, OR 1.256 for each 1mmHg increase in mean LAP, 95% CI 1.068-1.476). Moreover, a significant correlation was observed between FPD and mean LAP (r=0.503, p<0.0001). Prolonged FPD is associated with high LAP in AF patients without prominent left atrial enlargement. Pressure overload of the left atria might cause slowing of atrial electrical activation.

P Wave Signal-Averaged Electrocardiography in Patients with Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is associated with higher incidence of supraventricular arrhythmias. Atrial late potentials (ALP) detected by P-wave signal-averaged electrocardiography (SAECG) could be useful in detecting the patients at risk for supraventricular arrhythmias. Our objective was to assess the role of P-wave SAECG and ALP detection for arrhythmic risk evaluation of the patients with exacerbated COPD. We prospectively included 45 patients with exacerbation of COPD and 58 age- matched patients with no history of pulmonary disease in a control group. We performed pulmonary function tests, arterial blood gases, echocardiography, 24-hour Holter monitoring and P-wave SAECG. We measured filtered P-wave duration (FPD), the root mean square (RMS) voltages in the last 40, 30 and 20 ms of the filtered P-wave (RMS 40, RMS 30 and RMS 20), the root mean square voltage of the filtered P-wave potentials (RMS-p), and the integral of the potentials during the filtered P-wave (Integral-p). ALP was defined as FPD > 132 ms and RMS 20 < 2.3 μV. Isolated atrial premature beats (APB) and supraventricular tachycardias (SVT) were more frequent in the COPD group. There were no significant differences between groups regarding the P wave SAECG parameters. In the COPD group none of the supraventricular arrhythmias was correlated with ALP or any P-wave SAECG parameters. The patients with acute exacerbation of COPD but no apparent cardiac disease have a higher incidence of supraventricular arrhythmias. P-wave SAECG analysis and ALP detection have little value in the arrhythmic risk evaluation of these patients.

PROLONGED P WAVE DURATION IS NOT ASSOCIATED WITH SUBCLINICAL ATRIAL ARRHYTHMIAS IN MIDDLE-AGED ENDURANCE ATHLETES

PROLONGED P WAVE DURATION IS NOT ASSOCIATED WITH SUBCLINICAL ATRIAL ARRHYTHMIAS IN MIDDLE-AGED ENDURANCE ATHLETES

Value of P-wave signal averaging to predict atrial fibrillation recurrences after pulmonary vein isolation

Recurrences of atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA) are usually caused by pulmonary vein (PV) re-conduction, by foci outside the PV or by previous electrical remodelling. Substrate alterations with conduction delays may be detected by signal-averaged P-wave analysis (SAPW). This study was conducted to assess the value of the SAPW to predict recurrences after RFCA in patients with paroxysmal or persistent AF. One hundred and two patients (59 ± 10 years, 83 males) underwent a first RFCA procedure for paroxysmal (n = 61) or persistent/long-standing persistent (n = 41) AF. A SAPW recording with measurement of total filtered P-wave duration (FPD), P-wave integral, and terminal root mean squared voltage was obtained immediately after the ablation procedure and the patients were prospectively followed. During a mean follow-up of 12 ± 7 months, recurrences occurred in 36 of 102 (35.3%) patients, 17 of 61 with paroxysmal AF, and 19 of 41 with persistent AF (P = 0.06). The FPD was significantly longer in patients with recurrences compared to those without (158 ± 22 vs. 140 ± 18 ms, P = 0.0008). The FPD was shorter in patients with paroxysmal AF compared with patients with persistent AF (142 ± 28 vs. 153 ± 20 ms, P = 0.03). A FPD of 140 ms was found to discriminate patients prone to recurrences (log-rank test, P = 0.008) with a sensitivity of 69%, a specificity of 53%, a positive predictive value of 45%, and a negative predictive value of 76%. A FPD >140 ms is a marker of AF recurrences after RFCA and probably reflects the extent of atrial remodelling.

Abstract 9142: Post Procedural Changes of P-wave Duration can Predict Recurrence of Atrial Fibrillation after Circumferential Pulmonary Vein Isolation

Background: It has been reported that the significant shortening of P-wave duration after pulmonary vein isolation was related to successful outcome. However, the impact of the clinical outcomes after circumferential pulmonary vein isolation (CPVI) on the serial changes of P-wave characteristics is not clear. We hypothesized that the recurrence of atrial fibrillation (AF) prolonged P-wave duration and the recurrence of AF after CPVI affected the P-wave parameters by P-wave signal averaged electrocardiogram (P-SAECG). Methods: Fifty-nine patients (65±7years, 41 male) with AF (paroxysmal AF : n=44, persistent AF : n=15) who underwent CPVI alone and received P-SAECG at 2 days, 2 weeks, and 4weeks after CPVI were enrolled in this study. By using P-SAECG, the filtered P-wave duration (FPD) and root mean square voltage for the last 20msec (RMS20) were measured and the serial changes of FPD and RMS20 were calculated. AF recurrence was defined as patient's symptom and any episode of AF lasting &gt; 30 seconds on surface 12-leads ECG or 24-hour Holter ECG during follow-up periods except for 2 months post CPVI. Results: The patients were followed for 6±3 months. The recurrences of AF occurred in 18 of 59 patients (31%). The results of P-SAECG parameters were shown as table. The FPD of 2 days, 2weeks and 4weeks after CPVI in AF recurrence group was significantly longer than that in sinus rhythm (SR) maintenance group and the ΔFPD 4weeks in AF recurrence group was significantly prolonged than that in SR maintenance group. Using FPD 4weeks as cutoff value of &gt; 130.5 msec to predict AF recurrence, the sensitivity and specificity were 65% and 61%, respectively. Using ΔFPD 4weeks as cutoff value of &gt; 3.5 msec to predict AF recurrence, the sensitivity and specificity were 71% and 63%, respectively. Conclusion: The longer FPD and prolongation of FPD for one month after CPVI can predict the recurrence of AF after CPVI.

Short-term effects of eicosapentaenoic acid on P wave signal-averaged electrocardiogram in patients with coronary artery disease

The antiarrhythmic properties of n-3 polyunsaturated fatty acids (PUFAs) have been demonstrated in experimental models and in patients with coronary artery disease [1–6]. On the other hand, the signal-averaged electrocardiogram (SAECG) of the P waves has been used to predict the development of atrial fibrillation by measuring the filtered P wave duration (FPD) as an index of atrial conduction delay with high accuracy [7–10]. In this study, we assessed whether key long-chain n-3 PUFA, eicosapentaenoic acid (EPA) affected parameters of P wave SAECG in patients with coronary artery disease.

Timing of Atrial Fibrillation Recurrence Following Pulmonary Vein Isolation and Serial Changes of P-Wave Duration

Background: The terminal portion of the P-wave was correlated to the activation of pulmonary vein muscle and the shortening of P wave duration could predict successful outcomes after atrial fibrillation (AF) ablation. However, the mechanism of early recurrence of AF and late recurrence of AF are not clear. We investigated the relation between serial changes of P-wave duration and timing of AF recurrence. Method: Twenty-nine patients (66±7 years, 18 male) with recurrence of AF who underwent circumferential pulmonary vein isolation (CPVI) alone for drug resistant AF and received P-wave signal averaged electrocardiogram (P-SAECG) at 2 days, 2 weeks, and 4 weeks following CPVI were enrolled in this study. By using P-SAECG, the serial changes of the filtered P-wave duration (FPD) (ΔFPD 2 weeks = FPD 2 weeks-FPD 2 days, ΔFPD 4 weeks = FPD 4 weeks-FPD 2 days) were calculated. AF recurrence within 2 months post CPVI was defined as early recurrence. Results: ΔFPD 2 weeks in early recurrence of AF (ERAF group, n=21) was significantly longer than that in late recurrence of AF (LRAF, n=8), (4.2±9 vs. −6.6±11.7, p=0.04). However, ΔFPD 4 weeks in LRAF group was significantly longer than that in ERAF (14.2±7.6 vs. 6.8±9.5, p=0.02). Conclusion: The timing of recurrence of AF affected the serial changes of P-wave duration after CPVI.

The Consistency of Filtered P-Wave Duration among Different Electrocardiogram Instruments

Background: Filtered P-wave duration (fPWD) is used to estimate the severity of atrial remodeling associated with atrial fibrillation (AF). However, the consistency of fPWD measured by different ECG instruments has never been determined. The aim of this study is to compare fPWDs measured by FCP-7541 (Fukuda Denshi) and MAC5500 (GE Medical Systems). Methods: We enrolled 62 subjects (25 healthy adults and 37 non-valuvular paroxysmal AF patients). Signal averaged ECG was performed twice sequentially using 2 different ECG instruments, FCP-7541 installed with FP-705LP and MAC5500 with P Hi-Res. The P-wave signals were recorded from bipolar X, Y and Z leads until the noise amplitude reduced to 0.3 µV. Forward and backward Butterworth filter (40–300 Hz) was used in FCP-7541 and fast Fourier transform (FFT) filter (40–250 Hz) was applied in MAC5500. The filtered signals were combined into a vector magnitude of the P-wave. Results: Significant correlations between fPWDs by these 2 different instruments were observed (r=0.85, p<0.0001). However, fPWD measured by FCP7541 was significantly shorter than that by MAC5500 (129±13 vs. 121±13 ms, p<0.0001). Conclusion: Though there was an excellent correlation between the values of fPWD evaluated by FCP-7541 and those by MAC5500, those by FCP7541 were a little shorter than those by MAC5500. The interpretation of fPWD should be done with an understanding of possible difference between different ECG instruments.

Effects of angiotensin receptor blockade on serial P-wave signal-averaged electrocardiograms after electrical cardioversion of persistent atrial fibrillation

To evaluate the effects of the angiotensin II type 1 receptor blocker candesartan on P-wave signal-averaged electrocardiogram (P-SAECG) after electrical cardioversion in patients with atrial fibrillation (AF). One hundred and seventy-one patients with persistent AF were randomized to receive candesartan 8 mg/day or placebo for 3-6 weeks before and candesartan 16 mg/day or placebo for 6 months after electrical cardioversion. P-SAECG was recorded in 114 patients (57 in each treatment group) after cardioversion and repeated in those with sinus rhythm at 1 and 6 weeks, and 3 and 6 months. Filtered P-wave duration (FPD), root-mean-squared (RMS) voltages of the terminal 40 ms of the filtered P-wave, RMS voltage of the entire filtered P-wave, and the integral of the voltages in the entire PD were analysed. No effects of candesartan were observed on any P-SAECG parameter at baseline. In the subgroup of patients in sinus rhythm after 6 months, FPD was significantly shorter both at baseline (151 +/- 16 vs. 163 +/- 16 ms) and at 6 months (143 +/- 12 vs. 153 +/- 15 ms) in the candesartan (n = 15) compared with the placebo group (n = 21). Treatment with candesartan was associated with a shorter FPD in patients remaining in sinus rhythm for 6 months.

Prediction of Atrial Fibrillation with Atrial Late Potentials and Pathological Chemoreflexsensitivity

Atrial fibrillation (AF) is a very common arrhythmia that often causes the serious complication of a stroke. The aim was to evaluate the utility of pathological chemoreflexsensitivity (PCHRS) and atrial late potentials (ALP) to predict AF in follow-up. We investigated a prospective study on the basis of our observation about a PCHRS and ALP in paroxysmal AF. The PCHRS was predefined as a chemoreflexsensitivity below 3.0 ms/mmHg and ALP were predefined as a filtered P-wave duration > or =120 ms and a root mean square voltage of the last 20 ms of the P-wave < or =3.5 microV. A P-wave triggered P-wave signal averaged electrocardiograph (ECG) and chemoreflexsensitivity was performed on 250 consecutive patients who were divided into four groups. Group I consisted of patients with ALP and PCHRS, patients of group II had only ALP, a PCHRS was only present in group III, and patients of group IV had neither ALP nor PCHRS. During the mean follow-up of 37.8 months AF was observed in 10 patients (4%). The patients of the four groups were similar according to clinical baseline characteristics. The incidence of AF was higher in group I (18% of patients) than in group II (6% of patients, P = 0.229) and significantly higher than in group III (3% of patients, P = 0.034) or group IV (1% of patients, P < 0.0001). Patients with ALP and PCHRS showed a 33-fold risk (P < 0.001) for the onset AF. The results of our study suggest that the probability of AF could be predicted with a P-wave signal averaged ECG and an analysis of chemoreflexsensitivity. The predictive power of the combination of ALP and PCHRS seemed not high enough for risk stratification.

Prediction of atrial fibrillation in patients with cardiac dysfunctions†

Atrial fibrillation (AF) is a common arrhythmia in advanced heart failure. The occurrence of AF increases the risk of death and hospitalization for patients with heart failure. The results of different studies indicated that patients with paroxysmal AF have a longer filtered P wave duration (FPD), a lower root mean square voltage of the last 20 ms of the P wave (RMS 20), and a lower chemoreflexsensitivity (CHRS). Our study bases on these observations in order to examine the methods for predicting AF in patients with a left ventricular ejection fraction below 40% without a prior documentation of AF. The ratio between the difference of RR intervals in ECG and venous pO(2) before and after 5-min oxygen inhalation was measured (ms/mmHg) in order to determine the CHRS. A P wave signal-averaged ECG was performed for the measurement of FPD and RMS 20. The measurements were only performed in 94 patients with sinus rhythm. AF occurred during the mean follow-up of 39.9 months in 24 patients (26%). There were no significant differences concerning age, heart diseases, sex, ejection fraction, heart rate, or the use of drugs. The FPD (130.3 +/- 4.2 vs. 118.9 +/- 12.4 ms, P < 0.0001) was significantly longer and the RMS 20 (3.03 +/- 0.95 vs. 3.83 +/- 1.58 microV, P = 0.02) was significantly lower in patients with AF than in sinus rhythm. The CHRS did not differ significantly between both groups (3.57 +/- 1.49 vs. 3.48 +/- 1.62 ms/mmHg, P = 0.81). The chi(2) test showed that the threshold of FPD>or=125 ms and RMS 20 <or=3.3 microV revealed the best predictive value for AF. A stepwise logistic regression analysis of all variables identified the threshold of FPD>or=125 ms and RMS 20 <or=3.3 microV (OR 18.71; 95% CI, 4.85-72.16, P < 0.0001) as independent predictors for AF. In summary, our data show that the results of a P wave signal-averaged ECG can predict the risk for new onset of AF in patients with heart failure. The value of signal-averaged FPD is probably the result of reflecting the intra-atrial conduction delay, which is a pathophysiological condition for AF. The CHRS is not a suitable method for predicting AF.

Prediction of Conversion from Paroxysmal to Permanent Atrial Fibrillation

Paroxysmal atrial fibrillation (PAF) transits to permanent atrial fibrillation (PEAF). The current study was to determine whether a P wave-triggered P wave signal averaged electrocardiogram (P-SAECG) and chemoreflexsensitivity (CHRS) are useful to predict a conversion to PEAF in patients with PAF. The filtered P wave duration (FPD) and the root mean square voltage of the last 20 ms of the P wave (RMS 20) were measured by P-SAECG. The ratio between the difference of RR intervals in the ECG and venous pO2 before and after 5-minutes oxygen inhalation is measured (ms/mmHg) for the determination of CHRS. A total of 180 patients with PAF were enrolled and followed for a mean of 22.5 months. PEAF occurred in 38 patients (21%) and these patients had a significantly larger left atrial size (43.2 +/- 4.9 vs. 41.0 +/- 5.4 mm, P = 0.021), a significantly longer FPD (158.8 +/- 18.2 vs. 136.7 +/- 16.6 ms, P < 0.0001), and a significantly lower CHRS (1.96 +/- 0.99 vs. 2.44 +/- 1.19 ms/mmHg, P = 0.024) than patients with PAF. Patients with PEAF tended to have a lower RMS 20 (2.38 +/- 0.65 vs. 2.75 +/- 1.18 microV, P = 0.067) than patients with PAF. The chi(2) test showed that the combination of FPD > or = 145 ms, RMS 20 < or = 3.0 microV, left atrial size > or = 41 mm, and CHRS < or = 2.0 ms/mmHg had the best predictive power for PEAF. Patients who fulfilled these criteria had a 12-fold increased risk for a conversion from PAF to PEAF. Our results show that a P-SAECG, an analysis of CHRS, and left atrial enlargement are clinical predictors of a progression from PAF to PEAF.

Electrophysiological Properties of the Atrium After Cardioversion of Chronic Atrial Fibrillation Relation to the Plasma Brain Natriuretic Peptide Level

Brain natriuretic peptide (BNP) level has been shown to increase in patients with chronic atrial fibrillation (CAF) without overt heart failure (HF). Although atrial electrical remodeling associated with CAF has been described, little is known about the effects of the BNP level on the electrophysiological properties in CAF patients. In 42 CAF patients without overt HF, the atrial monophasic action potential duration (MAPD) at pacing cycle lengths (CLs) of 300-800 msec and P-wave signal-averaged electrograms were recorded after cardioversion. The MAPDs for all CLs were significantly longer in patients with a BNP concentration greater than the 50th percentile (group 1, BNP = 215 +/- 118.2 pg/mL) than in patients with a concentration less than the 50th percentile (group 2, BNP = 68.3 +/- 20.9 pg/mL), resulting in a similar value in the MAPDs at CLs of 350 and 600 msec for group 1 and the control patients (n = 8). The slope value of the MAPDs between CLs of 350 and 600 msec was normal in group 1, but slightly lower in group 2 than in group 1 and control patients. The filtered P-wave duration did not differ between the two groups. These electrophysiological characteristics related to the BNP level suggest that the atrial repolarization may be affected by a latent ventricular dysfunction.

O eletrocardiograma de alta resolução da ativação atrial em pacientes com ou sem fibrilação atrial paroxística

To analyze the parameters of the time domain P-wave signal-averaged electrocardiogram (P-SAECG) and compare them with the P-wave duration on the conventional electrocardiogram (P on ECG) as well as the left atrium diameter (LAD) and left ventricular ejection fraction (EF) obtained on the echocardiogram in order to evaluate patients with paroxysmal atrial fibrillation (PAF). One hundred and eighty-one patients were included in the study: 117 with confirmed PAF and 64 without PAF. The P-SAECG parameters used were: the filtered P-wave duration (FPD), the root mean square (RMS) voltages in the last 40, 30 and 20 ms of the filtered P-wave (RMS 40, RMS 30 and RMS 20), the root mean square voltage of the filtered P-wave potentials (RMS P), the integral of the potentials during the filtered P-wave (Integral P) and the filtered P-wave late potential durations below 3 microV (PL<3). The parameters that presented significant statistical differences between the groups were: FPD, RMS 40, 30 and 20, PL<3, P on ECG and LAD. The ROC curve calculations demonstrated the best cut-off points and performance estimates for each parameter: sensitivity, specificity, area under the curve and p-value (p). The time domain P-SAECG proved to be a superior method to identify patients with paroxysmal atrial fibrillation than the conventional electrocardiogram and echocardiogram.

Amiodarone prophylaxis for atrial fibrillation of high-risk patients after coronary bypass grafting: a prospective, double-blinded, placebo-controlled, randomized study

Atrial fibrillation (AF) occurs often in patients after coronary artery bypass grafting (CABG) and can result in increased morbidity and mortality. Previous studies using P-wave signal-averaged electrocardiogram (P-SAECG) have shown that patients with a longer filtered P-wave duration (FPD) have a high risk of AF after CABG. We have shown that patients with an FPD > or = 124 ms and a root-mean-square voltage of the last 20 ms of the P-wave 20 < or = 3.7 microV have an increased risk of AF after surgery. Accordingly, the aim of this study was to investigate whether or not prophylactic peri-operative administration of amiodarone could reduce the incidence of AF in this high-risk group undergoing CABG identified by P-SAECG. In this prospective, double-blinded, placebo-controlled, randomized study, 110 patients received either amiodarone (n = 55) or placebo (n = 55). During CABG, two patients of both groups died. Amiodarone was given as 600 mg oral single dose one day before and from days 2 through 7 after surgery. In addition, amiodarone was also administered intravenously during surgery in a 300-mg bolus for 1 h and as a total maintenance dose of 20 mg/kg weight over 24 h on the first day following surgery. The primary endpoint was the occurrence of AF after CABG. The secondary endpoint was the hospitalization length of stay after CABG. The baseline characteristics were similar in both treatment groups. The incidence of post-operative AF was significantly higher in the placebo group compared with the amiodarone group (85 vs. 34% of patients, P < 0.0001). The prophylactic therapy with amiodarone significantly reduced the intensive care (1.8 +/- 1.7 vs. 2.4 +/- 1.5 days, P = 0.001) and hospitalization length of stay (11.3 +/- 3.4 vs. 13.0 +/- 4.3 days, P = 0.03). In the amiodarone group, concentrations of amiodarone and desethylamiodarone differed significantly between patients with AF and sinus rhythm (amiodarone: 0.96 +/- 0.5 vs. 0.62 +/- 0.4 microg/mL, P = 0.02; desethylamiodarone: 0.65 +/- 0.2 vs. 0.48 +/- 0.1 microg/mL, P = 0.04). The incidence of post-operative AF among high-risk patients was significantly reduced by a prophylactic amiodarone treatment resulting in a shorter time of intensive care unit and hospital stay. Our data supports the prophylactic use of amiodarone in peri-operative period in patients at high risk for AF after CABG.

Atrial Electrophysiological Abnormality in Patients With Brugada Syndrome Assessed by P-Wave Signal-Averaged ECG and Programmed Atrial Stimulation

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. 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. 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.

Long-term outcome after cardioversion of atrial fibrillation: Prediction of recurrence with P wave signal averaged ECG and chemoreflexsensitivity

Aim The recurrence of atrial fibrillation after cardioversion was a general problem in medical practice. Methods We wanted to test the hypothesis that the recurrence of atrial fibrillation could be predicted by measurements of P wave triggered P wave signal averaged ECG and chemoreflexsensitivity (CHRS) in 118 consecutive patients one day after successful electrical cardioversion. We measured the filtered P wave duration (FPD) and the root mean square voltage of the last 20 ms of the P wave (RMS 20) with P wave triggered P wave signal averaged ECG. The CHRS was calculated of a ratio between the difference of RR intervals in ECG and venous pO 2 before and after 5-min oxygen inhalation. The pathologic CHRS was predefined as a CHRS below 3.0 ms/mm Hg. Results A recurrence of atrial fibrillation was observed in 57 patients (48%) during a 9.3-month follow-up. The left atrial size (41.9 ± 4.0 vs. 39.3 ± 3.1 mm, P < 0.0003) was larger, the FPD (139.6 ± 16.0 vs. 118.2 ± 14.1 ms, P < 0.0001) was longer, the RMS 20 (2.57 ± 0.77 vs. 3.90 ± 0.99 μV, P < 0.0001) and the CHRS (2.66 ± 1.18 vs. 4.01 ± 1.66 ms/mm Hg, P < 0.0001) were lower in patients with recurrence of atrial fibrillation. A cut-off point was defined with FPD ≥ 126 ms and RMS 20 ≤ 3.1 μV and could predict atrial fibrillation with a specificity of 77%, a sensitivity of 72%, a positive value of 75%, a negative predictive value of 75% and an accuracy of 75%. Patients with FPD ≥ 126 ms and RMS 20 ≤ 3.1 μV had nearly a 7-fold increase risk for recurrence of atrial fibrillation. Conclusion The recurrence of atrial fibrillation after cardioversion could be detected by P wave signal averaged ECG and an analysis of CHRS. These methods seem to be appropriate to show a delayed atrial conduction and a neurovegetative imbalance which might be possible trigger mechanisms of reinitiating of atrial fibrillation.

Effect of haemodialysis on signal-averaged electrocardiogram P-wave parameters

The P-wave signal-averaged electrocardiogram (SAECG) is a non-invasive technique considered to indicate an increased risk for paroxysmal atrial fibrillation. The study was designed to evaluate the effect of the haemodialysis (HD) process on SAECG parameters in the group of selected HD patients. Forty-seven HD patients (without relevant cardiac diseases) were included. SAECGs were performed pre- and post-dialysis together with evaluating extracellular body water (ECW) by using bioimpedance and biochemical measurements. For each SAECG, filtered P-wave duration (FPD) and root mean square voltage of the final 20 ms of filtered P-wave (RMS20) were established. The duration of either pre- or post-dialysis FDP was higher in HD patients than in the control group (P<0.001 and P = 0.005, respectively). The voltage of either pre- or post-dialysis RMS20 was reduced in HD patients compared with controls (P<0.001 in both cases). HD induced a decrease in the duration of the FDP and a significant increase in the voltage of RMS20 (P<0.001 in both cases). Stepwise multiple regression identified independent predictors of pre- and post-dialysis FDP as: (1) age; (2) pre- and post-dialysis ECW/kg body weight, respectively and; (3) pre- and post-dialysis haemoglobin levels, respectively. In the case of RMS20, we did not find any independent predictors either pre- or post-dialysis. Our study revealed that P-wave SAECG parameters are abnormal in a significant portion of HD patients and improved with HD process. We have also demonstrated that patients' age, volume status as well as the presence of anaemia are important factors influencing P-wave SAECG parameters in HD patients.