Diurnal variation of the P-wave dispersion in chronic ischemic heart diseases

P-wave dispersion: What we know till now?

P-wave dispersion is defined as the difference between the maximum and the minimum P-wave duration recorded from multiple different-surface ECG leads. It has been known that increased P-wave duration and P-wave dispersion reflect prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses, which are well-known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation. Extensive clinical evaluation of P-wave dispersion has been performed in the assessment of the risk for atrial fibrillation in patients without apparent heart disease, in hypertensives, in patients with coronary artery disease, in patients undergoing coronary artery bypass surgery, in patients with congenital heart diseases, as well as in other groups of patients suffering from various cardiac or non-cardiac diseases. In this paper, we aimed to summarize the measurement methods, current use in different clinical situations, strengths and limitations of the of P-wave dispersion.

P-wave duration changes and dispersion in preeclampsia

OBJECTIVE

The purpose of this research was to study P wave parameters to determine the association between preeclampsia and future cardiovascular risk and to study the possible correlation between P waves and severity of preeclampsia.

STUDY DESIGN

In this case-control study 58 pregnant women with preeclampsia and 30 normal pregnant women were compared by measuring maximum and minimum P-wave durations and P-wave dispersion (Pd) in the late third trimester.

RESULTS

Minimum P wave values were lower and Pd values were higher, both significantly, in the preeclampsia groups than in the control group. In addition, the Pd values of the severe preeclampsia group were higher compared to that of the mild preeclampsia group.

CONCLUSION

Preeclampsia predisposes the patient to future cardiovascular complications including atrial or ventricular arrhythmias, but validated tools to assess the risks are yet not available. P-wave duration and Pd constitute a recent contribution to the field of noninvasive electrocardiology. Our data clearly demonstrated that minimum P wave and Pd values were significantly altered in preeclamptic pregnant women when compared to the controls. This important association can be used to screen women for increased risk in order to better target counseling regardinglifestyle modifications and to follow up and manage women with a history of preeclampsia more closely.

Atrial electromechanical coupling interval and P-wave dispersion in healthy elderly

BACKGROUND AND AIMS

The aim of our study was to investigate the potential effect of natural aging on atrial fibrillation (AF) by means of electrocardiographic P-wave analysis and measurement of the transthoracic echocardiographic electromechanical coupling interval (EMC).

METHODS

The study comprised 25 healthy individuals aged ≥65 years (group 1) and 25 control subjects <65 years (group 2). The difference between maximum (Pmax) and minimum (Pmin) P-wave durations on 12-lead electrocardiography were defined as P-wave dispersion (PD). Intra- and inter-atrial EMC were measured by tissue Doppler imaging.

RESULTS

Pmax (107.2 ± 3.58 msec vs 100.0 ± 3.56 msec, p<0.001) and PD (43.6 ± 4.98 msec vs 36.5 ± 3.56 msec, p<0.001) were significantly higher in group 1 than in group 2. Left atrial EMC [24.6 (15.20) vs 13.3 (4.50), p<0.001] and inter-atrial EMC [43.2 (16.05) vs 33.3 (4.75), p<0.001] were significantly delayed in group 1 compared with group 2. There was a significant correlation between left atrial diameter, PD, Pmax, left atrial EMC, and inter-atrial EMC.

CONCLUSION

Aging is correlated with increased left atrial size and impaired diastolic relaxation, which may contribute to a greater risk of AF in terms of prolonged PD and atrial EMC.

Meta-analysis of p-wave dispersion values in healthy individuals: the influence of clinical characteristics

BACKGROUND

P-wave dispersion (Pd) is an appealing marker for predicting the risk of developing atrial fibrillation. At present, no definitive cutoff value has been determined as to the diagnosis of high-risk patients. Our aims were to evaluate P-wave parameters of healthy subjects published in the literature, determine normal range and weighted means of Pd and P-wave parameters, and investigate the influences of gender, age, and BMI on the weighted results.

METHODS

A systematic search of studies published in PubMed was conducted. Only studies which included control groups of healthy individuals were included.

RESULTS

Of the 657 studies initially identified, 80 were eligible for inclusion. The total number of participants was 6,827. The highest reported Pd values were 58.56 ± 16.24 ms; the lowest were 7 ± 2.7 ms. The weighted mean was 33.46 ± 9.65 ms; weighted median was 32.2 ms. Gender and age were not found to be associated with significant influences on P-wave parameter values. High-normal BMI was not found to be associated with increased P-wave parameter values.

CONCLUSIONS

Pd, Pmax, and Pmin span a wide range of values in healthy individuals. Seemingly, abnormal values were often reported in healthy adults. The high variability of P-wave parameters in healthy individuals, and overlapping of the results with those reported for patients with increased risk for atrial fibrillation, might suggest that this technique has limited sensitivity and specificity. The variability between studies may stem from methodological issues and, therefore, there is a definite need for methodological standardization of Pd measurements.

Atrial electromechanical coupling interval and P-wave dispersion in patients with white coat hypertension

BACKGROUND

The aim of our study was to investigate the effect of white coat hypertension (WCH) to atrial conduction abnormalities by electrocardiographic P-wave analysis and echocardiographic electromechanical coupling (EMC) interval measurement.

METHODS

The study consisted of sex-, age-, and body mass index-matched 24 patients with WCH, 24 patients with sustained hypertension (SH), and 24 subjects with normotension (NT). The difference between the maximum (Pmax) and minimum P-wave durations on 12-lead electrocardiography was defined as P-wave dispersion (PD). Intra- and inter-atrial EMC were measured by tissue Doppler imaging.

RESULTS

Pmax and PD of subjects with WCH were significantly higher than those of normotensives and lower than those of patients with SH. Inter-atrial EMC and left atrial EMC values of WCH group were intermediate between NT and SH groups. There was a significant correlation between left atrial diameter, PD, Pmax, left ventricle mass index, left atrial EMC, and inter-atrial EMC.

CONCLUSION

White coat hypertension is an intermediate group between SH and NT in terms of atrial electromechanical abnormalities which may be associated with the risk of atrial fibrillation.

The effect of altitude on P-wave and QT duration and dispersion

BACKGROUND

Short-term and long-term exposure to high altitude has been reported to change the surface electrocardiogram. We aimed to compare P-wave and QT parameters between healthy people living at high altitude and sea level.

METHODS

Twelve-lead electrocardiographies of 38 healthy people living at sea level (Antalya,Turkey) and 38 healthy people living at high altitude (Van, Turkey; 1,700-1,800 m) were obtained. Minimum and maximum P-wave durations, P-wave dispersion, minimum and maximum corrected QT intervals, and corrected QT dispersion were calculated.

RESULTS

There was no significant difference between the two groups in respect to heart rate and QT variables. Mean Pminimum values were slightly but significantly lower in the high altitude group (P = 0.029). Mean Pmaximum values tended to be lower at high altitude but did not reach statistical significance (P = 0.085). However, there was no significant difference in respect to P-wave dispersion values.

CONCLUSIONS

In a sample of men and women living at high altitude in Turkey, significant reduction of Pminimum and borderline reduction of Pmaximum duration, but no significant change of P-wave and QT dispersion, were observed.

Lack of diurnal variation of P-wave and QT dispersions in patients with heart failure

BACKGROUND

P-wave dispersion (PWD) is a new parameter for the assessment of risk of atrial fibrillation and has been reported to be increased in heart failure. Diurnal variation of the PWD has been reported in patients with coronary artery disease (CAD). QT dispersion (QTD) has also a circadian variation. In this study we aimed to search diurnal variation of PWD and QTD in patients with heart failure.

METHODS

Fifty-three clinical heart failure patients having left ventricular ejection fraction (LVEF) <40% were divided into two groups according to presence of CAD. Twelve-lead ECGs were obtained in the morning (07:00-08:00 hours), at noon (12:00-14:00 hours), and at night (22:00-24:00 hours).

RESULTS

All the patients were in New York Heart Association class II except one in class I. beta-blocker and angiotensin-converting enzyme inhibitor or angiotensin receptor blocker usage was over 80% and spiranolactone usage was around 75% in the study group. PWD and QTD were not significantly different between patients with (n = 27) and without (n = 26) CAD. There was no significant diurnal variation of P wave and QT parameters.

CONCLUSIONS

We found that PWD and QTD do not show diurnal variation in patients having either ischemic or nonischemic origin of heart failure treated with optimal drug therapy.

Incremental prevalence of fractionated and inhomogeneous propagation of sinus impulses with increasing atrial depolarization abnormality among outpatients

INTRODUCTION

Prolonged P-wave duration (P-dur) and excessive P-wave dispersion (P-disp) are purported arrhythmogenic substrates for atrial fibrillation. However, the extent of involvement of inhomogeneous, sinus impulse propagation demonstrated by excessive P-disp (> 40 ms) has not been evaluated in relation to increasing P-dur.

METHODS

We appraised our previously studied sample of 500 consecutively numbered, otherwise unselected, electrocardiograms (ECGs) of outpatients from the University of Massachusetts, Worcester, Massachusetts for P-disp, P-dur and P-wave axis (P-axis). P-disp, defined as the difference of the duration between the widest and narrowest P wave, and the greatest P-dur after a 12-lead ECG search, was measured manually to the nearest 10 ms. Normal P-axis was considered 0 to + 75 degrees by manually constructing the mean frontal plane electrical P-axis from the limb leads.

RESULTS

After excluding those with atrial arrhythmias, paced rhythms, errors in lead placement, P waves with low amplitude or overall technically poor tracing, 428 ECGs depicting sinus rhythm formed our final sample. P-dur was strongly associated with P-disp (p<0.0001) but the correlation remained weak (r=0.42). However, when P-dur was divided into 10 ms increments, the prevalence of abnormal P-disp rose incrementally with P-dur, with or without consideration of the P-axis. The prevalence of abnormal P-disp doubled from 30% in those with P-dur of 100 ms to > 60% in those with P-dur of 120 ms. Further, the prevalence exceeded 80% with P-dur of 130 ms and reached 100% with P-dur > 160 ms.

CONCLUSION

With increasingly prolonged atrial depolarization, the associated inhomogeneity of sinus impulse propagation across the atria increases. P-dur and P-disp are associated with each other and are consistent with abnormal atrial conduction properties.