P‐Wave Dispersion: A Novel Predictor of Paroxysmal Atrial Fibrillation

Background: The prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses are well known electrophysiologic characteristics in patients with paroxysmal atrial fibrillation (AF). Previous studies have demonstrated that individuals with a clinical history of paroxysmal AF show a significantly increased P‐wave duration in 12‐lead surface electrocardiograms (ECG) and signal‐averaged ECG recordings. Methods: The inhomogeneous and discontinuous atrial conduction in patients with paroxysmal AF has recently been studied with a new ECG index, P‐wave dispersion. P‐wave dispersion is defined as the difference between the longest and the shortest P‐wave duration recorded from multiple different surface ECG leads. Up to now the most extensive clinical evaluation of P‐wave dispersion has been performed in the assessment of the risk for AF in patients without apparent heart disease, in hypertensives, in patients with coronary artery disease and in patients undergoing coronary artery bypass surgery. P‐wave dispersion has proven to be a sensitive and specific ECG predictor of AF in the various clinical settings. However, no electrophysiologic study has proven up to now the suspected relationship between the dispersion in the atrial conduction times and P‐wave dispersion. The methodology used for the calculation of P‐wave dispersion is not standardized and more efforts to improve the reliability and reproducibility of P‐wave dispersion measurements are needed. Conclusions: P‐wave dispersion constitutes a recent contribution to the field of noninvasive electrocardiology and seems to be quite promising in the field of AF prediction. A.N.E. 2001;6(2):159–165     

Altered Interatrial Conduction Detected in MADIT II Patients Bound to Develop Atrial Fibrillation

Background: Changes in P‐wave morphology have recently been shown to be associated with interatrial conduction route used, without noticeable changes of P‐wave duration. This study aimed at exploring the association between P‐wave morphology and future atrial fibrillation (AF) development in the Multicenter Automatic Defibrillator Trial II (MADIT II) population. Methods : Patients included in MADIT‐II without a history of AF with sinus rhythm at baseline who developed AF during the study (“Pre‐AF”) were compared to matched controls without AF development (“No‐AF”). Patients were followed for a mean of 20 months. A 10‐minute high‐resolution bipolar ECG recording was obtained at baseline. Signal‐averaged P waves were analyzed to determine orthogonal P‐wave morphology, P‐wave duration, and RMS20. The P‐wave morphology was subsequently classified into one of three predefined types using an automated algorithm. Results: Thirty patients (age 68 ± 7 years) who developed AF during MADIT‐II were compared with 60 patients (age 68 ± 8 years) who did not. P‐wave duration and RMS20 in the Pre‐AF group was not significantly different from the No‐AF group (143 ± 21 vs 139 ± 30 ms, P = 0.26, and 2.0 ± 1.3 vs 2.1 ± 1.0 μV, P = 0.90). The distribution of P‐wave morphologies was shifted away from Type 1 in the Pre‐AF group when compared to the No‐AF group (Type 1/2/3/atypical; 25/60/0/15% vs 10/63/10/17%, P = 0.04). Conclusions: This study is the first to describe changes in P‐wave morphology in patients prior to AF development. The results indicate that abnormal interatrial conduction may play a role in AF development in patients with prior myocardial infarction and congestive heart failure.     

The Time Interval from the Initiation of the P‐Wave to the Start of Left Atrial Appendage Ejection Flow: Does It Reflect İnteratrial Conduction Time?

Recurrence of atrial fibrillation is more common in patients with atrial conduction delay. In the present study, we evaluated whether findings obtained from transesophageal echocardiography (TEE), a semi-invasive method, correlate with those from an invasive method, electrophysiologic study (EPS), in measuring interatrial conduction time. METHODS AND RESULTS: We compared two methods of calculating interatrial conduction time in a group of 33 patients. The origin of the P-wave on the surface electrocardiogram (ECG) was taken as the onset of atrial activation. The time interval from this point to the commencement of the left atrial appendage ejection flow (P-LAA) was measured by TEE. Meanwhile, simultaneous recordings of the left atrial appendage were obtained with a catheter positioned in the LAA, and an invasive interatrial conduction time was measured from the origin of the surface's earliest P-wave (I-IACT). The mean I-IACT (46.27 +/- 13.25 ms) correlated strongly with the mean P-LAA (49.91 +/- 12.72 ms; r = 0.839, P < 0.0001). CONCLUSION: The interatrial conduction time can be estimated with a relatively noninvasive method using P-LAA measurements. This technique can be applied widely in predicting AF recurrence, and appropriate therapy may be applied.     

Resumption of interatrial conduction after atrial premature beat in baseline interatrial aberrancy

Interatrial block (IAB) is a delay or blockage of interatrial conduction from the right atrium to the left atrium, causing prolongation of the P-wave duration on the electrocardiogram. This condition is unfortunately not uncommon in clinical practice, especially among the elderly. It is often overlooked because the P wave is small and abnormalities can be difficult to detect. An isolated IAB does not usually cause any abnormal symptoms and may not require any specific treatment. Nevertheless, a relationship between an IAB and other cardiovascular conditions including left atrial electromechanical dysfunction, atrial remodeling, atrial fibrosis, atrial fibrillation, and stroke has been reported. Early diagnosis of this condition is critical. This case report presents a functional interatrial block or interatrial aberrancy that returned to normal after an atrial premature complex where the interatrial conduction remained normal in subsequent beats.     

Paradoxical Effects of Interatrial Conduction Delay in a Hypertrophic Cardiomyopathy Patient in the Long‐Term: Time is a Great Healer

Paradoxical Effects of Interatrial Conduction Delay . We present a unique case where early proarrhythmic and late antiarrhythmic characteristics of interatrial conduction delay were observed during the long‐term progression of HCM. Occurrence of AT constantly increased as the interatrial conduction delay became more prominent, while the P‐wave width in sinus rhythm and the AT cycle length both showed an instantaneous increase in parallel. As the interatrial delay reached a critical point, the right and left atrial P‐wave became virtually separated, as demonstrated by the findings of ECGs and echocardiography. This phenomenon resulted in the complete cessation of tachycardias. (J Cardiovasc Electrophysiol, Vol. 22, pp. 587‐589 May 2011)     

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.     

The Bachmann Bundle and interatrial conduction

The cardiac conduction system (CCS) is responsible for generation and systematic conduction of cardiac impulses. The Bachmann Bundle (BB), considered one of its several accessory impulse-conducting pathways, plays a fundamental role in interatrial conduction. Delay in this pathway leads to prolongation of the P wave on the electrocardiogram (interatrial delay or block), which in turn is a precursor for atrial tachyarrhythmias, mainly atrial fibrillation and significant left atrial electromechanical dysfunction. As such, the magnitude of its sequelae has necessitated a flurry of investigations that have been targeted toward its prevention and management. Although current studies on the use of angiotensin-converting enzyme inhibitors and atrial pacing have indeed shown some promise, it would be shortsighted to overlook and circumvent the actual underlying lesion-BB abnormality. Thus, a thorough understanding of the CCS and interatrial conduction is essential. We review current literature on the BB and discuss potential mechanisms that affect its conduction.     

Atrial conduction delay and its association with left atrial dimension, left atrial pressure and left ventricular diastolic dysfunction in patients at risk of atrial fibrillation

BACKGROUND: Atrial conduction delay and its association with left atrial dimension, left atrial pressure and left ventricular (LV) diastolic dysfunction in patients at risk of atrial fibrillation (AF) may be assessed by high-resolution electrocardiography of P wave. OBJECTIVES: To determine how left atrial size, left atrial pressure and LV diastolic dysfunction, measured noninvasively by transthoracic echocardiography, influence atrial conduction time. METHODS: Signal-averaged electrocardiography of P wave and echocardiogram were performed on 70 patients (average age of 63+/-10 years; 37 male and 33 female), divided into three groups: group A, patients with paroxysmal AF (n=29); group B, patients with type 2 diabetes mellitus and arterial hypertension, but without AF (n=23); and group C, healthy control patients (n=18). Standard statistical methods were used. RESULTS: Filtered P wave duration, measured by signal-averaged electrocardiography, was significantly prolonged in group A and group B compared with control group C (138+/-12 ms and 125+/-9 ms versus 117+/-8 ms; P 相似文献   

Clinical usefulness of the atrial double potential at the intercaval region in the right atrium: a new index for inducibility of atrial fibrillation in electrophysiologic studies

The second deflection of the atrial double potential (DP) recorded at the intercaval region is considered to reflect the far-field potential of the left atrium. The conduction via the upper interatrial connection was evaluated utilizing this DP and the relationship between atrial fibrillation (AF) and the conduction via the interatrial connection evaluated. In 30 consecutive patients with the DP at the intercaval region, prolongation in the left atrial activation time during the right atrial extra stimulation was measured at the intercaval region (deltaDP) and the coronary sinus (deltaCS). The difference between deltaDP and deltaCS (deltaDP-deltaCS) was used as an index of inhomogeneity in interatrial conduction. The patients were divided into AF (n=13) and non-AF (n=17) groups in accordance with the inducibility of AF in the electrophysiologic study. The max deltaDP and the max ACS were greater in the AF group than in the non-AF group, i.e., max deltaDP (43+/-19 vs 27+/-17 ms, P=0.021), max deltaCS (35+/-15 vs 21+/-14 ms, P=0.029). The max absolute value(deltaDP-deltaCS) was also greater in t     

Susceptibility to Atrial Fibrillation:

Propensity for Extrastimulus to Induce AF. Introduction : The development of susceptibility to atrial fibrillation (AF) is a common consequence of many forms of cardiovascular disease, especially heart failure. In this study we used a sheep model of pacing-induced stable early heart failure to describe, quantify, and relate the level of susceptibility to AF to changes in structural and electrophysiologic parameters.
Methods and Results : Epicardial electrodes were implanted on the atria and right ventricles of nine sheep. The AF thresbold, atrial vulnerability period, atrial effective refractory period (ERP), and interatrial conduction time were examined during control and over a 6-week period of ventricular pacing at 190 beats/min. Left atrial (LA) area and left ventricular (LV) fractional shortening were monitored using echocardiography. There were significant increases in LA susceptibility to AF (P < 0.0003), LA area (P < 0.0002), and LA FRP400 (P < 0.0002). Rate of increase in LA area was related positively to AF susceptibility (P = 0.02) and inversely to LA ERP400 (P = 0.002). LV fractional shortening decreased to approximately 50% of control value (P < 0.00001). No changes were observed in right atrial electrophysiology.
Conclusion : In this study, susceptibility (the ability of an extrastimulus to induce AF) was rigorously measured within a predetermined format. Significant relationships were found to exist between susceptibility, certain of the observed changes in atrial electrophysiology and structure.     

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 .     

Progressive Interatrial Block and Supraventricular Arrhythmias

Interatrial conduction disorders are frequent in patients with structural heart diseases, including hypertension, coronary disease, and hypertrophic cardiomyopathy, and they are strongly associated with atrial tachyarrhythmias, especially atrial fibrillation and flutter. Conduction delays lead to dispersion of refractory periods and participate in initiating and maintaining reentry circuits, facilitating atrial arrhythmias. In this case, the changing pattern over time is a manifestation of progressive atrial remodeling and conduction delay. The terminal negative component of the P wave in the inferior leads suggests block of the electrical impulse in the Bachman bundle zone, with retrograde activation of the left atria via muscular connections at the coronary sinus. This has been reproduced in experimental models and confirmed by endocardial mapping. Physicians should be aware of the association between advanced interatrial block and development of atrial arrhythmias as its recognition could prompt early and aggressive antiarrhythmic treatment.     

Electrocardiographic left atrial enlargement electrophysiologic, echocardiographic and hemodynamic correlates

The mechanism of the electrocardiographic pattern termed left atrial enlargement was evaluated in 21 patients. Left atrial size and pressure as well as interatrial conduction were correlated with electrocardiographic left atrial enlargement using echocardiography, mean pulmonary capillary wedge pressure and activation time from the P wave to the coronary sinus. In the group as a whole only prolongation of interatrial conduction time was consistently related to the electrocardiographic pattern of left atrial enlargement; left atrial size or pressure was not predictably abnormal in patients with this pattern. Five patients had neither elevation of pulmonary capillary wedge pressure nor echocardiographic evidence of an enlarged left atrium. When the etiologic type of heart disease was analyzed, an enlarged left atrium correlated with electrocardiographic left atrial enlargement only in patients with rheumatic mitral valve disease (eight of nine patients). Elevated pulmonary capillary wedge pressure correlated with electrocardiographic left atrial enlargement in all four patients with cardiomyopathy. In patients with coronary artery disease the electrocardiographic pattern was unrelated to either left atrial pressure or volume overload. Thus, the electrocardiographic pattern termed left atrial enlargement appears to represent an interatrial conduction defect that can be produced by a variety of factors.     

Atrial Fibrillatory Wall Motion and Degree of Atrial Remodeling in Patients with Atrial Fibrillation: A Tissue Velocity Imaging Study

Introduction: The atrial fibrillation cycle length (AFCL) and the intracardiac atrial electrogram morphology may be used to characterize atrial fibrillation (AF). However, assessment of these parameters requires an invasive electrophysiological study. We assessed clinical and electrophysiological correlates of noninvasive tissue velocity imaging (TVI) of the right and left atrial myocardial fibrillatory wall motion. Methods and Results: We performed an electrophysiological study in 12 patients with AF referred for His bundle ablation. Using atrial electrograms, we determined the AFCL (AFCL‐egm) and electrophysiological AF type. Simultaneously, transthoracic echocardiography was performed. We used the TVI traces to determine the cycle length of the atrial fibrillatory wall motion (AFCL‐tvi) and atrial fibrillatory wall velocities (AFV‐tvi). AFCL‐tvi matched very well with AFCL‐egm (r²= 0.98; P < 0.001), both in the left and right atrium. Patients with permanent AF had shorter AFCL‐tvi (155 ± 15 ms vs 216 ± 23 ms; P < 0.001), higher AFCL‐tvi variability, and lower AFV‐tvi compared to patients with paroxysmal AF. Three electrophysiological AF types were found based on the morphology of the electrograms and these related to specific TVI patterns. Conclusion: TVI of the atrial fibrillatory wall motion may enhance noninvasive characterization of atrial remodeling in patients with atrial fibrillation.     

P wave assessment: state of the art update

Diagnostic (mapping) and therapeutic (ablation, pacing) advances have provided insightinto atrial depolarization processes and new developments in P wave analysis. Information about interatrial pathwaysis important to the understanding of interatrial conduction delay. A standardized method for P wave analysis isnecessary for the development of a clinical role for management of patients with paroxysmal atrial fibrillationusing signal-averaged P wave analysis and P wave dispersion. Algorithms for predicting localization of ectopic Pwaves may facilitate catheter ablation. P wave changes due to pacing at different atrial sites may be useful forpermanent pacing for prevention of atrial fibrillation. Introduction of these developments into clinical practiceshould allow better prevention and treatment of atrial arrhythmias and could have considerable impact in view oftheir high frequency especially in the older population.     

Atrial Conduction Disorders

Atrial conduction disorders result from impaired propagation of cardiac impulses from the sinoatrial node through the atrial conduction pathways. Disorders affecting interatrial conduction alter P-wave characteristics on the surface electrocardiogram. A variety of P-wave indices reflecting derangements in atrial conduction have been described and have been associated with an increased risk of atrial fibrillation (AF) and stroke. Interatrial block (IAB) is the most well-known of the different P-wave indices and is important clinically due to its ability to predict patients who are at risk of the development of AF and other supraventricular tachycardias. P-Wave Axis is a measure of the net direction of atrial depolarization and is determined by calculating the net vector of the P-wave electrical activation in the six limb-leads using the hexaxial reference system. It has been associated with stroke and it has been proposed that this variable be added to the existing CHA2DS2-VASc score to create a P2-CHA2DS2-VASc score to improve stroke prediction. P-Terminal Force in V1 is thought to be an epiphenomenon of advanced atrial fibrotic disease and has been shown to be associated with a higher risk of death, cardiac death, and congestive heart failure as well as an increased risk of AF. P-wave Dispersion is defined as the difference between the shortest and longest P-wave duration recorded on multiple concurrent surface ECG leads on a standard 12-lead ECG and has also been associated with the development of AF and AF recurrence. P-wave voltage in lead I (PVL1) is thought to be an electrocardiographic representation of cardiac conductive properties and, therefore, the extent of atrial fibrosis relative to myocardial mass. Reduced PVL1 has been demonstrated to be associated with new-onset AF in patients with coronary artery disease and may be useful for predicting AF. Recently a risk score (the MVP risk score) has been developed using IAB and PVL1 to predict atrial fibrillation and has shown a good predictive ability to determine patients at high risk of developing atrial fibrillation. The MVP risk score is currently undergoing validation in other populations. This section reviews the different P-wave indices in-depth, reflecting atrial conduction abnormalities.     

Simultaneous occurrence of atrial fibrillation and atrial flutter

INTRODUCTION: Early reports suggested that some patients with "atrial fibrillation/flutter" might have atrial fibrillation in one atrium and atrial flutter in the other. However, more recent conceptions of atrial fibrillation/flutter postulate that the pattern is due to a relatively organized (type I) form of atrial fibrillation. We report the occurrence and ECG manifestations of simultaneous atrial fibrillation and flutter in patients undergoing attempted catheter ablation of atrial flutter. METHODS AND RESULTS: In patients undergoing radiofrequency ablation for atrial flutter, an attempt was made to entrain atrial flutter by pacing in the right atrium. The arrhythmias observed occurred following attempts at entrainment, or spontaneously in one case. Twelve transient episodes of simultaneous atrial fibrillation and flutter were observed in five patients. The atrial fibrillation was localized to all or a portion of one atrium, during which the other atrium maintained atrial flutter. In each case, the surface 12-lead ECG reflected the right atrial activation pattern. No patients had interatrial or intra-atrial conduction block during sinus rhythm, suggesting functional intra-atrial block as a mechanism for simultaneous atrial fibrillation/flutter. CONCLUSION: In certain patients, the occurrence of transient, simultaneous atrial fibrillation and flutter is possible. In contrast to prior studies in which it was suggested that left atrial or septal activation determines P wave morphology, the results of the present study show that P wave morphology is determined by right atrial activation. Functional interatrial block appears to be a likely mechanism for this phenomenon.     

Atrial fibrillation in patients with Wolff-Parkinson-White syndrome: role of pulmonary veins

AF in WPW Syndrome. Aim: We aimed to characterize electrophysiological properties of pulmonary veins (PVs) in patients with Wolff–Parkinson–White (WPW) syndrome and atrial fibrillation (AF), and to compare them to those in patients with WPW without AF. Methods and Results: A total of 31 patients (mean age 40 ± 15 years, 23 males) with WPW were recruited: 16 patients with (AF group) and 15 without (controls) a history of AF. The basic electrophysiological (EPS) and echocardiographic data were not different between the 2 groups. Effective refractory periods (ERPs) of PVs were significantly shorter in the AF group compared to controls: left superior (LS) PV ERP 185±29 versus 230 ± 24 ms, P = 0.001; left inferior PV ERP 198 ± 25 versus 219 ± 26 ms, P = 0.04; right superior (RS) PV ERP 207 ± 25 versus 236 ± 19 ms, P = 0.001; right inferior PV ERP 208 ± 30 versus 240 ± 19 ms, P = 0.003. Maximal veno‐atrial conduction delay (i.e., the maximal prolongation of interval from stimulus delivered at PV ostia to proximal coronary sinus after extrastimulus compared to the basic drive cycle) was longer in the AF group when pacing from LSPV (69.3 ± 37.9 vs 32.6 ± 16.1 ms, P = 0.01) and RSPV (74.1 ± 25.9 vs 50.2 ± 26.5 ms, P = 0.04). During EPS, AF was induced more often in the AF group (n = 7) compared to controls (n = 1; P = 0.04). Follow‐up revealed that AF recurred in 3 patients in the AF group and none of the controls. Conclusion: Patients with WPW syndrome and AF have shorter ERPs of PVs and greater maximal veno‐atrial conduction delay compared to patients with WPW without AF. These findings suggest a potential role of PVs in the development of AF in patients with WPW. (J Cardiovasc Electrophysiol, Vol. 23 p. 280‐286, March 2012.)     

Significant prolongation of atrial monophasic action potential duration: short-term reverse electrophysiological changes after internal cardioversion of atrial fibrillation

OBJECTIVE: Since short action potentials and short refractory periods facilitate the induction of atrial reentry, this maladaptation has been proposed as the pathophysiological basis of the frequent immediate recurrences of atrial fibrillation (IRAF) after internal cardioversion. However, short-term reverse electrophysiological changes of the atria after cardioversion have not been studied in humans. METHODS: Thirty-seven patients with chronic atrial fibrillation of 16+/-19 months and ten patients with an atrial fibrillation duration < or =48 h underwent internal cardioversion. Antiarrhythmic medication was only continued in 10 patients (21%), who were on amiodarone before cardioversion. Atrial monophasic action potential duration at 90% repolarization (APD(90)), sinus rate, P wave duration and interatrial conduction times between high right atrium and coronary sinus were recorded at min 0, 1, 3, 5, 10, 15 and 20 after cardioversion. RESULTS: Internal cardioversion was successful in all patients, but twelve of the patients with chronic AF (32%) and three of the patients with intermittent AF (30%) had one to four episodes of IRAF after 16+/-28 s. There was a significant 52+/-30 ms APD(90) prolongation, 83% of which occurred in min 0-3 (P<0.0001) and 17% in min 3-20 (P<0.05) after internal cardioversion. There was no significant temporal change in sinus rate, P-wave and interatrial conduction time during the time studied. APD(90) prolongation and its time dependence did not show a detectable difference in subgroups with chronic AF, IRAF, left atrial size >40 mm and treatment with amiodarone. CONCLUSIONS: There is a significant prolongation of action potential duration in min 0-3 after internal cardioversion of atrial fibrillation, whereas sinus rate and intra- and interatrial conduction time remain unchanged. APD(90) prolongation in min 0-3 shows a temporal relationship to the high rate of immediate recurrences of atrial fibrillation during this time interval. The data imply that there is a transient recovery of atrial refractoriness after cardioversion and suggest a mechanism of the high rate of early recurrences of atrial fibrillation.