Abnormal P‐Wave Morphology Is a Predictor of Atrial Fibrillation Development and Cardiac Death in MADIT II Patients

Background: Several ECG‐based approaches have been shown to add value when risk‐stratifying patients with congestive heart failure, but little attention has been paid to the prognostic value of abnormal atrial depolarization in this context. The aim of this study was to noninvasively analyze the atrial depolarization phase to identify markers associated with increased risk of mortality, deterioration of heart failure, and development of atrial fibrillation (AF) in a high‐risk population with advanced congestive heart failure and a history of acute myocardial infarction. Methods: Patients included in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) with sinus rhythm at baseline were studied (n = 802). Unfiltered and band‐pass filtered signal‐averaged P waves were analyzed to determine orthogonal P‐wave morphology (prespecified types 1, 2, and 3/atypical), P‐wave duration, and RMS20. The association between P‐wave parameters and data on the clinical course and cardiac events during a mean follow‐up of 20 months was analyzed. Results: P‐wave duration was 139 ± 23 ms and the RMS20 was 1.9 ± 1.1 μV. None of these parameters was significantly associated with poor cardiac outcome or AF development. After adjustment for clinical covariates, abnormal P‐wave morphology was found to be independently predictive of nonsudden cardiac death (HR 2.66; 95% CI 1.41–5.04, P = 0.0027) and AF development (HR 1.75; 95% CI 1.10–2.79, P = 0.019). Conclusion: Abnormalities in P‐wave morphology recorded from orthogonal leads in surface ECG are independently predictive of increased risk of nonsudden cardiac death and AF development in MADIT II patients. Ann Noninvasive Electrocardiol 2010;15(1):63–72     

Interatrial Mechanical Dyssynchrony Worsened Atrial Mechanical Function in Sinus Node Disease With or Without Paroxysmal Atrial Fibrillation

Introduction: Atrial electromechanical dysfunction might contribute to the development of atrial fibrillation (AF) in patients with sinus node disease (SND). The aim of this study was to investigate the prevalence and impact of atrial mechanical dyssynchrony on atrial function in SND patients with or without paroxysmal AF. Methods: We performed echocardiographic examination with tissue Doppler imaging in 30 SND patients with (n = 11) or without (n = 19) paroxysmal AF who received dual‐chamber pacemakers. Tissue Doppler indexes included atrial contraction velocities (Va) and timing events (Ta) were measured at midleft atrial (LA) and right atrial (RA) wall. Intraatrial synchronicity was defined by the standard deviation and maximum time delay of Ta among 6 segments of LA (septal/lateral/inferior/anterior/posterior/anterospetal). Interatrial synchronicity was defined by time delay between Ta from RA and LA free wall. Results: There were no differences in age, P‐wave duration, left ventricular ejection fraction, LA volume, and ejection fraction between with or without AF. Patients with paroxysmal AF had lower mitral inflow A velocity (70 ± 19 vs 91 ± 17 cm/s, P = 0.005), LA active empting fraction (24 ± 14 vs 36 ± 13%, P = 0.027), mean Va of LA (2.6 ± 0.9 vs 3.4 ± 0.9 cm/s, P = 0.028), and greater interatrial synchronicity (33 ± 25 vs 12 ± 19 ms, P = 0.022) than those without AF. Furthermore, a lower mitral inflow A velocity (Odd ratio [OR]= 1.12, 95% Confidence interval [CI] 1.01–1.24, P = 0.025) and prolonged interatrial dyssynchrony (OR = 1.08, 95% CI 1.01–1.16, P = 0.020) were independent predictors for the presence of AF in SND patients. Conclusion: SND patients with paroxysmal AF had reduced regional and global active LA mechanical contraction and increased interatrial dyssychrony as compared with those without AF. These findings suggest that abnormal atrial electromechanical properties are associated with AF in SND patients.     

Prediction of the Recurrence of Atrial Fibrillation After Successful Cardioversion with P Wave Signal‐Averaged ECG

Background: The recurrence of atrial fibrillation (AF) was often observed after cardioversion. Methods: In our study, a P wave triggered P wave signal‐averaged ECG (P‐SAECG) was performed on 118 consecutive patients 1 day after successful electrical cardioversion in order to evaluate the utility of this method to predict AF after 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). Results: During a 1‐year follow‐up, a recurrence was observed in 57 patients (48%). Patients with recurrence of AF had a larger left atrial size (41.9 ± 4.0 vs 39.3 ± 3.1 mm, P < 0.0003), a longer FPD (139.6 ± 16.0 vs 118.2 ± 14.1 ms, P < 0.0001), and a lower RMS 20 (2.57 ± 0.77 vs 3.90 ± 0.99 μV, P < 0.0001). A cutoff point (COP) of FPD ≥126 ms and RMS 20 ≤3.1 μV could predict AF 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%. A stepwise logistic regression analysis of variables identified COP (odds ratio 9.97; 95% CI, 4.10–24.24, P < 0.0001) as an independent predictor for recurrence. Conclusions: We conclude that the probability of recurrence of AF after cardioversion could be predicted by P‐SAECG. This method seems to be appropriate to demonstrate a delayed atrial conduction that might be a possible risk factor of reinitiation of AF.     

The Value of P Dispersion on Predicting Atrial Fibrillation After Coronary Artery Bypass Surgery: Effect of Magnesium on P Dispersion

Background: AF is a frequent arrhythmia complicating CABG, and it is well known that dispersion and prolongation of P wave increases the risk of AF. The aim of this study was to investigate the effect of magnesium (Mg) treatment on P‐wave duration and dispersion in patients undergoing CABG. Method: The study included 148 consecutive patients (33 women, 115 men; mean age 62.1 ± 7.0 years) undergoing CABG who were randomly allocated to two groups. Group A consisted of 93 patients to whom 1.5 g daily MgSO₄ infusion was applied the day before surgery, just after operation, and 4 days following surgery, and group B consisted of 55 control patients. From the preoperative and postoperative fourth day, 12‐lead ECG recordings, duration of the P waves, and P‐wave dispersions were calculated. Results: There were no differences between the two groups with regard to age, sex, and blood Mg level. Comparison of the baseline and day 4 ECG measurements showed no difference as far as heart rates, duration of PQ, and QRS intervals were concerned. AF developed in 2 (2%) cases in group A and in 20 (36%) cases in group B (P < 0.001). There was no difference between the two groups when average basal P max, P min, P dispersion, and day 4 P min values were compared. In group A, fourth day P max (94.3 ± 11.8 vs 101.0 ± 13.2 ms; P = 0.0025) and P dispersion (38.2 ± 9.2 vs 44.9 ± 10.9 ms; P = 0.0002) were significantly lower as compared to group B. Comparing the patients who developed AF, and who did not, no difference was detected with regard to baseline P max, P min, P dispersion, and day 4 P min. Day 4 P max (95.1 ± 11.8 vs 106.4 ± 14.0 ms, P = 0.0015) and P dispersion (38.9 ± 8.8 vs 50.7 ± 13.0 ms, P = 0.001) of patients who developed AF were significantly higher. Baseline Mg levels were similar in patients who developed AF, and who did not, but the day 4 Mg level was significantly lower in AF group (2.0 ± 0.23 vs 2.15 ± 0.26 mg/dL, P < 0.001). Conclusion: Perioperative Mg treatment reduces P dispersion and the risk of developing AF in patients undergoing CABG. A.N.E. 2002;7(3):211–218     

A novel finding of the atrial substrate properties and long-term results of catheter ablation in chronic atrial fibrillation patients with left atrial spontaneous echo contrast

Atrial Substrate Properties in Chronic AF Patients with LASEC. Background: The atrial substrate in chronic atrial fibrillation (AF) patients with a left atrial spontaneous echo contrast (LASEC) has not been previously reported. The aim of this study was to investigate the atrial substrate properties and long‐term follow‐up results in the patients who received catheter ablation of chronic AF. Methods: Of 36 consecutive patients with chronic AF who received a stepwise ablation approach, 18 patients with an LASEC (group I) were compared with 18 age‐gender‐left atrial volume matched patients without an LASEC (group II). The atrial substrate properties including the weighted peak‐to‐peak voltage, total activation time during sinus rhythm (SR), dominant frequency (DF), and complex fractionated electrograms (CFEs) during AF in the bi‐atria were evaluated. Result: The left atrial weighted bipolar peak‐to‐peak voltage (1.0 ± 0.6 vs 1.6 ± 0.7 mV, P = 0.04), total activation time (119 ± 20 vs 103 ± 13 ms, P < 0.001) and DF (7.3 ± 1.3 vs 6.6 ± 0.7 Hz, P < 0.001) differed between group I and group II, respectively. Those parameters did not differ in the right atrium. The bi‐atrial CFEs (left atrium: 89 ± 24 vs 92 ± 25, P = 0.8; right atrium: 92 ± 25 vs 102 ± 3, P = 0.9) did not differ between group I and group II, respectively. After a mean follow‐up of 30 ± 13 month, there were significant differences in the antiarrhythmic drugs (1.1 ± 0.3 vs 0.7 ± 0.5, P = 0.02) needed after ablation, and recurrence as persistent AF (92% vs 50%, P = 0.03) between group I and group II, respectively. After multiple procedures, there were more group II patients that remained in SR, when compared with group I (78% vs 44%, P = 0.04). Conclusion: There was a poorer atrial substrate, lesser SR maintenance after catheter ablation and need for more antiarrhythmic drugs in the chronic AF patients with an LASEC when compared with those without an LASEC. (J Cardiovasc Electrophysiol, Vol. pp. 1‐8)     

Rationale and design of the BAYES (Interatrial Block and Yearly Events) registry

The prevalence of interatrial block (IAB ) is high in the elderly, particularly in those with heart disease. Despite this high prevalence—and the association of IAB with the risk of atrial fibrillation (AF ), stroke, and cognitive decline—little information exists about the prognosis of older patients with IAB . P‐wave duration and morphology are associated with risk of developing AF , stroke, and cognitive decline in elderly patients with structural heart disease. The aim of the Interatrial Block and Yearly Events (BAYES ) registry is to assess the impact of IAB on the risk of AF and stroke during 3 years of follow‐up. A series of 654 ambulatory patients age ≥70 years with heart disease from 35 centers will be included in 3 similar‐size groups of patients. Group A: normal P‐wave duration (<120 ms); Group B: partial IAB (P‐wave duration ≥120 ms without biphasic [plus/minus] morphology in the inferior leads II , III , and aVF ); and Group C: advanced IAB (P‐wave duration ≥120 ms with biphasic [plus/minus] morphology in the inferior leads II , III , and aVF ). Patients will be managed according to current recommendations. The 2 primary endpoints are defined as (1) AF duration >5 minutes and documented in any form of electrocardiographic recording; and (2) stroke. Results from this study might significantly improve the knowledge of IAB and its impact on the outcome of elderly patients with heart disease and could open the door to the use of anticoagulation therapy in some elderly patients with IAB .     

P‐Wave Signal‐Averaged Electrocardiogram Predicts Atrial Fibrillation After Coronary Artery Bypass Grafting

Background: AF is one of the most common complications after CABG. The aim of the study was to identify the risk factors for postoperative AF. Methods: Between June and December 2000, 129 consecutive patients (72 men, 47 women; mean age 67 ± 6 years) underwent preoperative signal‐averaged electrocardiogram (SAECG) with assessment of filtered P‐wave duration (fPWD) and of the root mean square voltage of the last 10 and 20 ms of atrial depolarization (RMSV10 and RMSV20, respectively) before CABG. Results: Fifty‐six (43%) patients developed one episode of AF lasting > 30 seconds at a mean distance of 2.6 ± 1.8 days after surgery (group A), while 73 patients remained in sinus rhythm (group B). No differences between the two groups were found in terms of age, sex, P‐wave duration on the standard ECG, left atrial dimensions, and operative characteristics. In contrast, group A patients showed a significantly longer fPWD (138 ± 10 vs 111 ± 9 ms; P < 0.001) and smaller RMSV10 and RMSV20 (2.8 ± 1.0 vs 4.3 ± 1.1 μV, P < 0.001; 4.2 ± 2.1 vs 6.2 ± 2.0 μV, P < 0.001). Multivariate analysis indicated only fPWD as an independent predictor of AF (P = 0.009). With a cut‐off value of 135 ms for fPWD, the occurrence of AF could be predicted with a sensitivity of 84%, a specificity of 73%, a negative predictive value of 85%, and a positive predictive value of 70%. Conclusion: Preoperative SAECG is a simple exam that correctly identifies patients at higher risk of AF after CABG. A more widespread use of this technique can be suggested. A.N.E. 2002;7(3):198–203     

P‐Wave Morphology: Underlying Mechanisms and Clinical Implications

Increasing awareness of atrial fibrillation (AF) and its impact on public health revives interest in identification of noninvasive markers of predisposition to AF and ECG‐based risk stratification. P‐wave duration is generally accepted as the most reliable noninvasive marker of atrial conduction, and its prolongation has been associated with history of AF. However, patients with paroxysmal AF without structural heart disease may not have any impressive P‐wave prolongation, thus suggesting that global conduction slowing is not an obligatory requirement for development of AF. P‐wave morphology is therefore drawing increasing attention as it reflects the three‐dimensional course of atrial depolarization propagation and detects local conduction disturbances. The factors that determine P‐wave appearance include (1) the origin of the sinus rhythm that defines right atrial depolarization vector, (2) localization of left atrial breakthrough that defines left atrial depolarization vector, and (3) the shape and size of atrial chambers. However, it is often difficult to distinguish whether P‐wave abnormalities are caused by atrial enlargement or interatrial conduction delay. Recent advances in endocardial mapping technologies have linked certain P‐wave morphologies with interatrial conduction patterns and the function of major interatrial conduction routes. The value of P‐wave morphology extends beyond cardiac arrhythmias associated with atrial conduction delay and can be used for prediction of clinical outcome of a wide range of cardiovascular disorders, including ischemic heart disease and congestive heart failure.     

Effects of Right Coronary Artery PTCA on Variables of P‐Wave Signal Averaged Electrocardiogram

Background: P‐wave signal averaged ECG has been used to detect atrial late potentials that were found in paroxysmal atrial fibrillation. Ischemia is supposed to trigger ventricular late potentials, which indicate an elevated risk for ventricular tachycardia. Preexistent ventricular late potentials measured by ventricular signal averaged ECG is supposed to be eliminated by successful PTCA. Methods: We examined the incidence of atrial late potentials in patients with a proximal stenosis of the right coronary artery and new onset of atrial fibrillation. Furthermore, we investigated the anti‐ischemic effect of a successful percutaneous transluminal coronary angioplasty.(PTCA) of the right coronary artery. P‐wave signal averaged ECG from 23 patients who had a PTCA of the right coronary artery (group A) were compared to age, sex, and disease‐matched control subjects (group B) one day before, one day after, and one month after PTCA. Results: A new appearance of paroxysmal atrial fibrillation was presented in eight patients before PTCA (group A1) of group A. Patients with a stenosis of the right coronary artery had a significantly higher incidence of supraventricular extrasystoles in a 24‐hour‐Holter ECG (131.1 ± 45.4 vs 17.1 ± 18.9, P < 0.0002 ). The duration of the filtered P wave was longer (124.8 ± 11.9 vs 118.5 ± 10.1 ms, P < 0.04 ) and the root mean square of the last 20 ms (RMS 20) was significantly lower in group A than in group B (2.87 ± 1.09 vs 3.97 ± 1.12 μV, P < 0.01 ). A successful PTCA caused an increase in RMS 20 (2.87 ± 1.11 vs 4.19 ± 1.19 μV, P < 0.02 ) and a decrease in filtered P‐wave duration (124.8 ± 11.9 vs 118.4 ± 10.4 ms, P < 0.04 ). Preexistent atrial late potentials were found among 15 patients before PTCA. After successful PTCA only 3 out of 15 patients were affected (P < 0.0004) after one day, as well as after one month. All patients with a history of atrial fibrillation did not suffer from an arrhythmic recurrence within the following six months after successful PTCA. Conclusion: A stenosis of the right coronary artery is associated with atrial late potentials. A successful PTCA of the right coronary artery eliminates preexistent atrial late potentials and may reduce the risk of atrial fibrillation.     

High‐Resolution Signal‐Averaged Analysis of Atrial Electromagnetic Characteristics in Patients with Paroxysmal Lone Atrial Fibrillation

Background: Abnormalities in the electromagnetic signal of the atria during sinus rhythm could serve as markers of triggering foci or substrate for atrial fibrillation (AF). We examined atrial electrophysiologic properties noninvasively by using magnetocardiographic mapping (MCG) in patients with paroxysmal lone AF to find whether any difference exists between those who have frequent triggers of AF and who don't. Methods: MCG was recorded over anterior chest during sinus rhythm in 80 patients with paroxysmal lone AF (44 ± 12 years, 61 males) and 80 matched controls. Atrial wave duration (Pd) and root mean square amplitudes of the last 40 ms (RMS40) of the averaged filtered atrial complex were determined automatically. Patients expressing atrial arrhythmias triggering AF episodes were classified as focal AF. Results: The Pd was 109 ms in patients and 104 ms in controls (P = 0.007). In focal AF (72%) the Pd was slightly prolonged and its proportion of the PR interval was larger, but RMS40 was normal compared to controls. In other patients, the Pd was close to controls, but the RMS40 was reduced (59 ± 17 vs74 ± 36 fT, P = 0.006). Pd and atrial RMS amplitudes were unrelated to duration of AF history or frequency of recurrences. Conclusion: Clinical subclasses of lone AF seem to possess distinct signal profiles of atrial depolarization. Differences in electrophysiological properties between these subclasses may reflect pathogenetic variation and could have implications on diagnostics and therapy.     

Efficacy of adjuvant anterior left atrial ablation during intracardiac echocardiography-guided pulmonary vein antrum isolation for atrial fibrillation

Background: Recent data have shown that the septum and anterior left atrial (LA) wall may contain “rotor” sites required for AF maintenance. However, whether adding ablation of such sites to standard ICE‐guided PVAI improves outcome is not well known. Objective: To determine if adjuvant anterior LA ablation during PVAI improves the cure rate of paroxysmal and permanent AF. Methods: One hundred AF patients (60 paroxysmal, 40 persistent/permanent) undergoing first‐time PVAI were enrolled over three months to receive adjuvant anterior LA ablation (Group I). These patients were compared with 100 randomly selected, matched first‐time PVAI controls from the preceding three months who did not receive adjuvant ablation (Group II). All 200 patients underwent ICE‐guided PVAI during which all four PV antra and SVC were isolated. In group I, a decapolar lasso catheter was used to map the septum and anterior LA wall during AF (induced or spontaneous) for continuous high‐frequency, fractionated electrograms (CFAE). Sites where CFAE were identified were ablated until the local EGM was eliminated. A complete anterior line of block was not a requisite endpoint. Patients were followed up for 12 months. Recurrence was assessed post‐PVAI by symptoms, clinic visits, and Holter at 3, 6, and 12 months. Patients also wore rhythm transmitters for the first 3 months. Recurrence was any AF/AFL >1 min occurring >2 months post‐PVAI. Results: Patients (age 56 ± 11 years, 37% female, EF 53%± 11%) did not differ in baseline characteristics between group I and II by design. Group I patients had longer procedure time (188 ± 45 min vs 162 ± 37 min) and RF duration (57 ± 12 min vs 44 ± 20 min) than group II (P < 0.05 for both). Overall recurrence occurred in 15/100 (15%) in group I and 20/100 (20%) in group II (P = 0.054). Success rates did not differ for paroxysmal patients between group I and II (87% vs 85%, respectively). However, for persistent/permanent patients, group I had a higher success rate compared with group II (82% vs 72%, P = 0.047). Conclusions: Adjuvant anterior LA ablation does not appear to impact procedural outcome in patients with paroxysmal AF but may offer benefit to patients with persistent/permanent AF.     

Factors Associated with the Development of Atrial Fibrillation in COPD Patients: The Role of P‐Wave Dispersion

Background: Supraventricular tachyarrhythmia is a common problem in chronic obstructive pulmonary disease (COPD) patients. The purpose of this study is to analyze the factors associated with paroxysmal atrial fibrillation (AF) in COPD patients. Methods: Forty COPD patients (38 male, 2 female, mean age 60 ± 9 years) and 33 healthy controls (29 male, 4 female, mean age: 58 ± 10 years) were included in this study. Echocardiography, 24‐hour ambulatory and 12‐lead ECG, pulmonary function tests, arterial blood gases, and serum electrolytes were measured. On ECG, maximum (P_max) and minimum (P_min) duration of P wave and its difference, P‐wave dispersion (PWd), were measured. Results: On echocardiography, diastolic dysfunction was found in 14 of the 40 (35%) COPD patients. Heart rate variability analysis revealed that COPD patients had decreased SDANN, SDNN, SDNNIDX in time‐domain, and decreased LF in frequency domain parameters. Fourteen of the 40 COPD patients (35%) had AF. Patients with AF were older (57 ± 10 vs 64 ± 5 years, P = 0.03) and had lower SDANN, SDNN, and LF/HF ratio as compared to patients without AF in univariate analysis. All P‐wave intervals (P_max P_min and PWd) were increased in COPD patients compared to controls. P‐wave dispersion was significantly increased in COPD patients with AF, as compared to patients without AF (57 ± 11 vs 44 ± 7 ms, P = 0.001). In logistic regression analysis PWd was found to be the only factor associated with the development of AF (P = 0.04). Conclusions: The presence of AF was significantly related to the prolongation of PWd, but not with pulmonary function, arterial blood gasses, and left and right atrial function. A.N.E. 2002;7(3):222–227     

The Effect of Exercise to P Wave Dispersion and Its Evaluation as a Predictor of Atrial Fibrillation

Aim: Prolongation of P wave time and increase of its dispersion as an independent predictor of atrial fibrillation. In patients with paroxysmal atrial fibrillation (PAF) as in healthy people, exercise augments sympathetic activity and therefore can cause the development of atrial fibrillation. The aim of this study is to evaluate the effect of exercise on P wave dispersion and to predict the development of atrial fibrillation. Methods: One hundred and ninety‐eight patients (93 women, 105 men, mean age: 59.05 ± 11.01 years ) having the diagnosis of PAF were included in the study. The left atrial diameter of all these patients was more than 4.0 cm. One hundred and fifty‐five patients (72 females, 83 males, mean age: 58.41 ± 10.79 years ), with left atrial diameter more than 4.0 cm and without PAF were taken as control group. Symptom limited exercise test with modified Bruce protocol was performed on all patients. Rest, maximum exercise and recovery, and first, third, and fifth‐minute 12‐derivation ECG was taken in all patients. The velocity of ECG was adjusted to 50 mm/s; shortest and largest P wave durations were measured and P wave dispersion was calculated. Results: The mean left atrial diameter was 4.41 ± 0.58 cm in PAF patients and 4.38 ± 0.48 cm in control group. No differences were found between PAF patients with the controls in exercise time (10.38 ± 2.93 vs 10.81 ± 2.75 minutes ); METs (6.98 ± 1.72 vs 7.28 ± 1.75 minutes ); resting heart rate (79.13 ± 14.86 vs 79.69 ± 10.43 bpm ); peak heart rate (146.83 ± 23.21 vs 146.94 ± 16.13 bpm ). Maximum exercise P wave duration and P wave dispersion were greater than the rest measurements in PAF group (respectively P < 0.0001 and P = 0.0004 ). Conclusion: In PAF patients, P wave dispersion is significantly longer at rest, maximum exercise and recovery time than in a control group without PAF.     

Maximum P Wave Duration and P Wave Dispersion in Adult Patients with Secundum Atrial Septal Defect: The Impact of Surgical Repair

Background: Patients with atrial septal defect (ASD) have an increased risk for atrial fibrillation (AF). Previously it was shown that maximum P wave duration and P wave dispersion in 12‐lead surface electrocardiograms are significantly increased in individuals with a history of paroxysmal AF. We studied P maximum and P dispersion in adult patients with ASD during normal sinus rhythm. In addition, the impact of surgical closure of ASD on these variables within 1 year after surgery was evaluated. Methods: Thirty‐four patients (21 women, 13 men; mean age: 35 ± 11 years) operated on for ostium secundum type ASD and 24 age‐matched healthy subjects (13 women, 11 men; mean age: 37 ± 10 years) were investigated. P maximum, P minimum, and P dispersion (maximum – minimum P wave duration) were measured from the 12‐lead surface electrocardiography. Results: P maximum was found to be significantly longer in patients with ASD as compared to controls (115.2 ± 9 vs 99.3 ± 14 ms; P < 0.0001). In addition, P dispersion of the patients was significantly higher than controls (37 ± 9 vs 29.8 ± 10 ms; P = 0.003). P minimum was not different between the two groups (P = 0.074). After surgical repair of ASD, 10 patients (29%) experienced one or more episodes of paroxysmal AF. Patients with postoperative AF were older (45 ± 6 vs 30 ± 10 years; P = 0.001), and had a higher preoperative pulmonary artery peak systolic pressure as compared to those without postoperative AF (51 ± 11 vs 31 ± 9 mmHg; P < 0.0001). No significant difference in the pulmonary‐to‐systemic flow ratio was observed preoperatively between the two groups (P = 0.56). P maximum and P dispersion were significantly higher in patients with postoperative paroxysmal AF at baseline and at postoperative first month, sixth month, and first year as compared to those without it (for P maximum P = 0.027, P = 0.014, P = 0.001, P < 0.0001, respectively; for P dispersion P = 0.037, P = 0.026, P = 0.001, P < 0.0001, respectively). In addition, in patients with postoperative AF, no significant changes were detected in both of these P wave indices during postoperative follow‐up. However, in the other group, P maximum and P dispersion were found to be significantly decreased at postoperative 6 months and 1 year as compared to baseline. P minimum was similar throughout the postoperative follow‐up as compared to baseline in both groups. Conclusions: Mechanical and electrical changes in atrial myocardium may cause greater P maximum and P dispersion in patients with ASD. Surgical closure of the ASD can regress these pathological changes of atrial myocardium with a result in decreased P maximum and P dispersion. However, higher P maximum and P dispersion at baseline, which have not decreased after surgery, may be associated with postoperative paroxysmal AF, especially for older patients.     

Randomized Study of Early Intravenous Esmolol Versus Oral Beta‐Blockers in Preventing Post‐CABG Atrial Fibrillation in High Risk Patients Identified by Signal‐Averaged ECG: Results of a Pilot Study

Background: Patients with prolonged signal‐averaged ECG have four times higher risk for development of atrial fibrillation (AF) after coronary artery bypass surgery (CABG). Incidence of AF is reduced, but not eliminated by prophylaxis with beta‐blockers. The limitations of prophylaxis with oral beta‐blockers may be related to the delayed effect of oral therapy. We performed a pilot study of the efficacy of early intravenous esmolol and an oral beta‐blocker regimen for prevention of postoperative AF. Methods: Fifty patients referred for CABG and considered to be at high risk for postoperative AF on the basis of prolonged signal‐averaged ECG P wave duration > 140 ms were randomized to receive either a 24‐hour infusion of esmolol 6–18 hours after CABG, at an average dose 67 ± 7 μ/kg/min, followed by oral beta‐blockers versus oral beta‐blockers only beginning on postoperative day 1. Results: Seven of 27 patients (26%) in the esmolol group and 6 of 23 patients (26%) in the oral beta‐blocker group developed postoperative AF, P = NS. The mean time of onset of AF (2.7 ± 0.5 vs 2.7 ± 0.3 postoperative day, P = NS) and the median duration of AF (10 [2192] vs 7 [1.16] hours, P = NS) were similar between the two groups. Eleven (41%) patients treated with esmolol developed adverse events (hypotension: 8, bradycardia requiring temporary pacing: 2, left ventricular failure:1 patient) as compared to only one patient (4%) in the beta‐blocker group who developed hypotension, P = 0.006. Conclusions: This randomized controlled pilot study suggests that intravenous esmolol is less well tolerated and offers no advantages to standard beta‐blocker in preventing AF after CABG. A.N.E. 2002;7(2):86–91     

Evolution of P‐Wave Morphology in Healthy Individuals: A 3‐Year Follow‐Up Study

Background: Orthogonal P‐wave morphology in healthy men and women has been described using unfiltered signal‐averaged technique and holds information on interatrial conduction. The stability of P‐wave morphology in healthy subjects over time is not fully known. Methods: Sixty‐seven healthy volunteers were investigated (29 males, aged 63 ± 14 years, 48 females, 60 ± 13 years). Orthogonal lead data (X, Y, and Z) were derived from standard 12‐lead ECGs (recording length 6 minutes, sampling rate 1kHz, resolution 0.625 μV) recorded at baseline (BL), and 3 years later at follow‐up (FU). P waves were then signal‐averaged and analyzed regarding P‐wave morphology, locations of maxima, minima, zero‐crossings, and P‐wave duration (PWD). Results: No differences of P‐wave variables were observed at FU compared to BL, including PWD (127 ± 12 vs 125 ± 14 ms at BL and FU, respectively, n.s.). In 59 of the 67 subjects (88%), the P‐wave morphology was unaltered at FU. However, in the remaining eight cases a distinctively different morphology was observed. The most common change (P = 0.030) was from negative polarity to biphasic (?/+) in Lead Z (n = 5). In one case the opposite change was observed and in two cases transition into advanced interatrial block morphology was evident at FU. Conclusions: In the majority of healthy subjects, P‐wave morphology is stable at 3‐year FU. Subtle morphological changes, observed principally in Lead Z, suggest variation of interatrial conduction. These changes could not be detected by measuring conventional PWD that remained unchanged in the total population.     

Increased P‐Wave Duration and P‐Wave Dispersion in Patients with Aortic Stenosis

Background: P‐wave dispersion (PWD), defined as the difference between the maximum and minimum P‐wave duration, has been proposed as being useful for the prediction of paroxysmal atrial fibrillation (AF). AF is the most common arrhythmia and an important prognostic indicator for clinical deterioration in patients with aortic stenosis (AS). The aim of the present study was to evaluate PWD in patients with AS. Methods: The study population consisted of two groups: Group I consisted of 98 patients with AS (76 men, 22 women; aged 63 ± 8 years) and group II consisted of 98 healthy subjects (same age and sex) without any cardiovascular disease. A 12‐lead electrocardiogram was recorded for each subject. The P‐wave duration was calculated in all leads of the surface electrocardiogram. The difference between the maximum and minimum P‐wave duration was calculated and was defined as the PWD. All patients and control subjects were also evaluated by echocardiography to measure the left atrial diameter, left ventricular ejection fraction, left ventricular wall thicknesses, and the maximum and mean aortic gradients. Patients were also evaluated for the presence of paroxysmal AF. Results: Maximum P‐wave duration and PWD of group I were found to be significantly higher than those of group II. In addition, patients with paroxysmal AF had significantly higher PWD than those without paroxysmal AF. There was no significant difference between the two groups regarding minimum P‐wave duration. In addition, there was no significant correlation between echocardiographic variables and PWD. Conclusion: PWD, indicating increased risk for paroxysmal AF, was found to be significantly higher in patients with AS than in those without it. Further assessment of the clinical utility of PWD for the prediction of paroxysmal AF in patients with severe AS will require longer prospective studies.     

Impact of a patent foramen ovale on paroxysmal atrial fibrillation ablation

Introduction: A patent foramen ovale (PFO) is located at the anterior and superior part of the anatomical interatrial septum, the area that is targeted during transseptal puncture. This study sought to investigate the impact of accessing the left atrium via a PFO on paroxysmal AF ablation. Methods: From March 2004, 203 patients (55 ± 11 years) underwent catheter ablation for paroxysmal AF (80 ± 71 months), with the endpoint being electrical isolation of all pulmonary veins (PV) and AF noninducibility. The presence of a PFO was determined by both transesophageal echocardiography and catheter probing. Procedural difficulty was evaluated by radiofrequency (RF), procedural, and fluoroscopic durations. Clinical follow‐up was also investigated. Results: A PFO was detected in 27 patients (13%) by transesophageal echocardiography and in 22 additional patients (total 49 patients, 24%), by catheter probing (P < 0.001). A PFO was associated with longer total RF applications (57 ± 19 vs 51 ± 18 min, P = 0.04) and RF applications to isolate the PVs (42 ± 16 vs 35 ± 12 min, P = 0.001). Procedural and fluoroscopic times were unaffected. Seventy‐three patients (36%) required a second procedure; there was no difference in the number of PV reconnections (1.3 vs 1.8 veins, P = NS). After a mean follow‐up of 19 ± 9 months, 194/203 patients (96%) were free of AF, with no difference in patients in whom a PFO had been used. Conclusion: Although isolation of PVs is longer, overall procedural duration and success is not affected when using a PFO compared with a transseptal puncture. The presence of a PFO is underestimated by transesophageal echocardiography with brachial injection when compared with catheter probing.     

Predictive Value of P‐Wave Signal‐Averaged Electrocardiogram for Atrial Fibrillation in Acute Myocardial Infarction

Background: Atrial fibrillation (AF) is a common complication of acute myocardial infarction (AMI) with a reported incidence of 7–18%. Recently, P‐wave signal‐averaged electrocardiogram (P‐SAECG) has been used to assess the risk of paroxysmal AF attacks in some diseases. The aim of this study was to determine prospectively whether patients with AMI at risk for paroxysmal AF would be identified by P‐SAECG and other clinical variables. Methods: A total of 100 patients (mean age: 59 ± 12 , 77 male, 23 female) with ST segment elevation AMI were enrolled in this study. Patients with chronic AF were excluded. At entry, all patients underwent standard 12‐lead ECG and in the first 24 hours, P‐SAECG was taken, and echocardiography and coronary angiography were performed on the patients. Patients are followed for a month in terms of paroxysmal AF attacks and mortality. Results: AF was determined in 19 patients (19%). In patients with AF, abnormal P‐SAECG more frequently occurred than in patients without AF (37% vs 15%, P < 0.05) . Patients with AF were older (70 ± 14 vs 56 ± 10, P < 0.001) and had lower left ventricular ejection fraction (42%± 8 vs 49%± 11, P < 0.05) . AF was less common in thrombolysis‐treated patients (47% vs 74%, P <0.05) . Thirty‐day mortality was higher in patients with AF (16% vs 2%, P = 0.05) . Conclusions: An abnormal P‐SAECG may be a predictor of paroxysmal AF in patients with AMI. Advanced age and systolic heart failure were detected as two important clinical risk factors for the development of AF.