P-wave Parameters Research Articles

P-Wave Dispersion in Patients with Constrictive Pericarditis of Non-Ischemic Etiology Including Tubercoulous and Non-Tuberculous Subjects: A Pilot Study

Background: Although P-wave dispersion has proven to be a reliable electrocardiographic predictor of Atrial Fibrillation (AF) in many clinical settings, its significance in patients with Constrictive Pericarditis (CP) of non-ischemic origin is to be reported. Objectives: This study aimed to find out whether p-wave dispersion is prolonged in patients with documented CP of non-ischemic origin. Patients and Methods: This study was conducted on twenty patients with CP, 16 males and 4 females, with the mean age of 39.0 ± 20.5 years and 20 age- and sex-matched healthy subjects. All the Electrocardiograms (ECGs) were scanned and the P-wave parameters were measured electronically after × 400% magnification. Results: Our main finding was a significantly prolonged maximum P-wave duration (P = 0.018) and P-wave dispersion (P = 0.049) in the patients with CP compared to the control group. These parameters, however, did not have any correlation with the patients’ age and disease duration. Conclusions: Since AF is common in patients with CP of any etiology and may have a negative impact on their outcome, detection of individuals susceptible to development of AF could be of great clinical value.

Association of P-Wave Dispersion with Overall and Cardiovascular Mortality in Hemodialysis Patients

Background/Aims: The P-wave parameters that are measured using a 12-lead electrocardiogram are commonly used as noninvasive tools for assessing left atrial enlargement. This study was designed to assess whether P-wave dispersion is associated with overall and cardiovascular mortality in hemodialysis patients. Methods: This study enrolled 209 hemodialysis patients. We measured the P-wave dispersion corrected by heart rate, that is, the corrected P-wave dispersion (PWdisperC), and assessed its correlation with overall and cardiovascular mortalities. Results: The mean PWdisperC of all the patients was 93.3 ± 21.1 ms. During the follow-up period (mean 5.4 years), 58 deaths and 37 cardiovascular deaths were recorded. The adjusted value of PWdisperC was also associated with overall (hazards ratio (HR) 1.018, 95% CI 1.004-1.033, p = 0.014) and cardiovascular (HR 1.032, 95% CI 1.012-1.053, p = 0.002) mortalities. Multivariate Cox regression analysis identified tertile 3 of PWdisperC (vs. tertile 1) to be associated with overall (HR 2.472, 95% CI 1.181-5.174, p = 0.016) and cardiovascular (HR 3.896, 95% CI 1.463-10.376, p = 0.007) mortalities, after adjustment for demographic, clinical and biochemical parameters. Adding PWdisperC to a model of clinical features could significantly improve the predictive value for overall (p = 0.044) and cardiovascular (p = 0.002) mortalities. Conclusions: We concluded that PWdisperC was positively associated with overall and cardiovascular mortalities in hemodialysis patients and could provide additional prognostic values. Screening hemodialysis patients by using PWdisperC may facilitate identifying a group of patients with poor prognosis.

Impact of catheter ablation on P-wave parameters on 12-lead electrocardiogram in patients with atrial fibrillation

BackgroundCatheter ablation has emerged as a widely used treatment modality for atrial fibrillation (AF). P-wave abnormalities have been described in the patients with AF, and catheter ablation may potentially further impact P-wave parameters due to ablation of atrial tissue. MethodsWe reviewed data on P-wave parameters (P-wave duration, amplitude and P-wave duration and amplitude product) in leads V1 and aVF and changes in the P-terminal force (Ptf; product of duration and amplitude of terminal part of P-wave) in lead V1 from 12-lead electrocardiograms obtained prior to and after CA of a total of 46 (28 paroxysmal and 18 persistent) AF patients. ResultsThe median age of patients in our study was 63 (range: 30–77) years. We noticed a significant reduction in the P-wave duration (from 87.39±28.62ms at baseline to 72.09±24.59ms; p=0.0072) and the product of P-wave duration and amplitude in lead V1 (12.16±5.54mVms at baseline to 8.30±5.78mVms, p=0.0015) after CA. There was also a significant decrease in P-wave duration (from 92.57±19.67ms at baseline to 76.48±16.32ms after CA, p=0.0001) and P-wave duration and amplitude product in lead aVF (12.61±4.05mVms at baseline to 9.77±3.86mVms after CA, p=0.0001). CA also led to a significant decrease in Ptf (from 4.56±1.88 at baseline to 2.85±1.42mVms, p<0.0001). ConclusionRadiofrequency catheter ablation of AF leads to modification of P-wave parameters with substantial diminution in both the amplitude and duration of the P-wave in leads V1 and aVF. This likely represents reduction in electrically active atrial tissue after ablation, and may serve as a marker for the extent of ablated atrial tissue.

P-wave duration and dispersion in Holter electrocardiography of patients with obstructive sleep apnea

Introduction There is an association between obstructive sleep apnea (OSA) and atrial fibrillation (AF) with remained unclear underlying mechanisms. We investigated P-wave parameters as indicators of atrial conduction status among OSA patients. Materials and methods This cross-sectional study was conducted on 42 untreated OSA patients diagnosed using polysomnography and categorized to mild (6), moderate (18), and severe (18) OSA based on the apnea/hypopnea index (AHI). The control group consisted of 18 healthy subjects without any sleep or cardiac complaints. We applied 24-h Holter electrocardiography for measurement of P-wave parameters including duration and dispersion. Results No significant difference was observed among the groups in P-wave duration ( P = 0.281). P-wave dispersion and P max were significantly longer in those with moderate ( P = 0.002 and 0.014, respectively) and those with severe OSA ( P = 0.001 and 0.003, respectively) than controls. No correlation was found between age, gender, and BMI with P-wave parameters. AHI was significantly correlated with the P max ( r = 0.407, P = 0.012) and P-wave dispersion ( r = 0.431, P = 0.008). With linear regression analysis controlling for age, gender, and BMI, the AHI was independently associated with P-wave dispersion (â = 0.482, P = 0.002). Conclusion The severity of OSA is associated with prolonged P max and P-wave dispersion, indicating that patients with severe OSA have more severe disturbance in atrial conduction. This is the first study which has used Holter monitoring for measurement of P-wave parameters and repeating this study in a larger sample of patients is warranted. Acknowledgements This study is supported by the Isfahan University of Medical Sciences. We are thankful to Reihaneh Sadat Daneshmand who participated in designing the Holter monitoring software, and also we are thankful to Foroogh Hesabi, head of department of Holter monitoring of Noor Hospital (Isfahan).

Shoulder hand syndrome in hemispheric stroke

Shoulder hand syndrome in hemispheric stroke

Significant Correlation of P-Wave Parameters With Left Atrial Volume Index and Left Ventricular Diastolic Function

BackgroundThe 12-lead electrocardiogram (ECG) is a commonly used tool to access left atrial enlargement, which is a marker of left ventricular diastolic dysfunction (LVDD). The aim of this study was to evaluate any association of the P-wave measurements in ECG with left atrial volume (LAV) index and LVDD. MethodsThis study enrolled 270 patients. In this study, 4 ECG P-wave parameters corrected by heart rate, that is, corrected P-wave maximum duration (PWdur-MaxC), corrected P-wave dispersion (PWdisperC), corrected P-wave area (PWareaC) and corrected mean P-wave duration (meanPWdurC), were measured. LAV and left ventricular diastolic parameters were measured from echocardiography. LVDD was defined as a pseudonormal or restrictive mitral inflow pattern. ResultsThe 4 P-wave parameters were significantly correlated with the LAV index after adjusting for age, sex, diabetes, hypertension, coronary artery disease, body mass index and diastolic blood pressure in multivariate analysis. The standardized β coefficients of PWdurMaxC, PWdisperC, meanPWdurC and PWareaC were 0.338, 0.298, 0.215 and 0.296, respectively. The 4 P-wave parameters were also significantly correlated with LVDD after multivariate logistic regression analysis. The odds ratios (95% confidence intervals) of PWdurMaxC, PWdisperC, meanPWdurC and PWareaC were 1.03 (1.01–1.04), 1.02 (1.04–1.04), 1.04 (1.02–1.07) and 1.01 (1.00–1.02), respectively. ConclusionsThis study demonstrated that PWdurMaxC, PWdisperC, meanPWdurC and PWareaC were important determinants of the LAV index and LVDD. Therefore, screening patients by means of the 12-lead ECG may be helpful in identifying a high-risk group of increased LAV index and LVDD.

Seismic anisotropy analysis at the Low-Noise Underground Laboratory (LSBB) of Rustrel (France)

Abstract Seismic anisotropy of a fractured karstic limestone massif in sub-parallel underground galleries is studied. As the fractures are mostly vertically oriented, the seismic properties of the massif are approximated by horizontal transverse isotropy (HTI). Several data inversion methods were applied to a seismic dataset of arrival-times of P and S-waves. The applied methods include: isotropic tomography, simple cosine function fit, homogeneous Monte-Carlo anisotropic inversion for the parameters of horizontal transverse isotropy and anisotropic tomography for tilted transversely isotropic bodies. All methods lead to the conclusion that there is indeed an anisotropy present in the rock massif and confirm the direction of maximum velocity parallel to the direction of fracturing. Strong anisotropy of about 15% is found in the studied area. Repeated measurements show variations of the P-wave parameters, but not of the S-wave parameters, which is reflecting a change in water saturation.

Physiological Values of P-Wave Dispersion in Silesian Breed Horses and Polish Primitive Horses

Abstract Electrocardiographic examinations were performed on 45 Silesian breed horses (group K, 3-16-year-old, 16 stallions, 29 mares) and on 25 Polish Primitive breed horses (group P, 1.5-19-year-old, two stallions, six geldings, 17 mares). Einthoven and chest leads were used. P-wave dispersion was electronically evaluated. There was no correlation between P-wave dispersion and other ECG parameters, age, sex, body mass, or month of pregnancy. The average value of P-wave dispersion for all horses was 30.77 ms (SD 3.92 ms), however in particular groups it was: in group P - 31.89 ms (SD 3.07 ms), and in group K - 30.15 ms (SD 4.27 ms). The maximum value of P-wave dispersion in the studied population was 40 ms, in groups P and K - 37,6 ms and 40 ms, respectively. The physiological value of P-wave dispersion for the group of horses was below 45 ms.

High-Frequency Spectral Decay in P-Wave Acceleration Spectra and Source Parameters of Microearthquakes in Southeastern Sicily, Italy

In widely used ω −2 source models the characteristics of high-frequency radiation are described as being flat for frequencies between the source corner fre- quency and an upper limiting frequency fmax. Deviations from this behavior are de- scribed in a parameter κ, which is understood as a general measure of the changes the signal undergoes on its way from the source to the receiver. In this study, we calculated κ in southeastern Sicily by using microearthquakes belonging to three different seis- mic sequences occurring in the area in 1990, from 1999 to 2000, and in 2002. The selected events form four different clusters whose seismic sources are located within a 2-km radius. Although the source-to-station paths are approximately the same inside a given cluster, the values of κ change considerably at the same recording site from one event to another, also in the case of events having the same magnitude. We parame- terized κ in terms of event (κ E ) and path (κ P and κ Diff ) contributions. The term κ P represents the contribution on total κ of both the whole source-to-station path and the near-surface geology, while κ Diff models the possible spatial variation in the parameter measured with respect to a reference source-station direction. Results show that the source contribution is not negligible and that a positive correlation with source size exists. Moreover, the hypothesis of a laterally homogeneous crustal structure within the area in question is not appropriate, and significant variation in attenuating proper- ties of the medium may occur in a very small distance range (also in the order of a few tens of meters). Our analysis suggests that the origin of the previously mentioned variability is located near the recording site. Synthetic spectra are also computed in order to verify the actual significance of the parameterization employed and its capacity to separate the source and the path contribution to κ. We describe our spectra as a product of a Brune-type source spectrum and an exponential shaping term accounting for propagation effects. The seismic moments range between 3:8 × 10 11 and 5:2 × 10 13 N · m, the source radii range between 176 and 669 m, while the stress drop varies from 0.01 to 0.67 MPa. Online Material: Tables of stations in the deployed portable seismic networks, coordinates, and average values of κ.

P-wave parameters and cardiac repolarization indices: Does menopausal status matter?

Background and purposeData regarding electrocardiographic characteristics of postmenopausal women are lacking. In this prospective, cross-sectional study, electrocardiographic P-wave parameters and cardiac repolarization indices of age-matched pre- and postmenopausal healthy women were compared. We hypothesized that menopausal status would have a significant effect on cardiac electrical activity and hence electrocardiography (ECG) recordings. Materials and methodsTwelve-lead ECG recordings were obtained from 125 consecutively recruited postmenopausal healthy women aged between 44 and 54years. The control group consisted of 125 age-matched premenopausal women. P-wave parameters and cardiac repolarization indices were measured and compared with respect to menopausal status. ResultsDemographic features of premenopausal and postmenopausal women were comparable. There were no significant differences between two groups regarding mean values of heart rate, maximum and minimum P-wave duration, P-wave dispersion, maximum and minimum QT interval, and QT dispersion. Mean values of QT interval obtained from lead V5 were also similar. Corrected values which were calculated according to Bazett and Fridericia formulas also did not differ between the groups. Mean values of Tpeak to Tend (TpTe) (p<0.001) and corrected TpTe (p=0.001) intervals obtained from lead V5 were significantly shorter in postmenopausal women when compared to those without menopause. ConclusionTpeak to Tend interval decreased significantly while QT intervals and P-wave parameters did not change in postmenopausal women when compared to premenopausal women. Association of these findings with changes in levels of sex steroids and their prognostic implications need to be elucidated with further studies.

Electrocardiographic P-wave characteristics in patients with end-stage renal disease: P-index and interatrial block

P-wave parameters including P-wave dispersion (P d) have been examined in general population to predict development of atrial fibrillation (AF). But data on end-stage renal disease (ESRD) population are limited. P index (Pi) and interatrial block (IAB) as novel parameters may more accurately predict AF and have not been previously investigated in ESRD patients. We aimed to evaluate these novel ECG parameters in ESRD patients. Eighty-six HD, 47 CAPD, and 43 age- and gender-matched control subjects were enrolled in the study. P-wave duration was measured in all 12-leads of the surface ECG. The standard deviation of the P-wave duration across the 12 ECG leads was accepted as a Pi. P-wave duration above and equal to 110 ms was defined as IAB. All P-wave parameters were evaluated digitally by two observers. Pi was found to be significantly different among the groups in ANOVA. In post hoc analysis, P i was increased in HD group compared with the control group (p = 0.01). Also, P i tended to increase in CAPD group compared with controls (p = 0.06). The effect of ESRD on P i was independent of age, gender, and systolic blood pressure in univariate covariant analysis. The prevalence of IAB was 61, 55, and 32 % in patients with HD, CAPD, and controls, respectively (p = 0.001). P d was significantly higher in HD group compared with healthy controls. However, Pd values of CAPD patients did not show significant difference compared with controls. The present study demonstrated that IAB frequency and Pi were increased in patients with ESRD.

Analysis of maximum P-wave duration and dispersion after percutaneous closure of atrial septal defects: Comparison of two septal occluders

Amplatzer septal occluder (ASO) is the most widely used device for closure of atrial septal defect (ASD). Figulla septal occluder (FSO) is a similar device to ASO with some structural innovations. The aim of study is to assess the maximum P-wave duration (Pmax) and dispersion (Pd) in patients who underwent ASD closure with both devices, to determine the effects of structural innovations on atrial electrical inhomogeneity. The study is a retrospective cohort analysis. Between December 2005 and March 2010, 121 patients underwent percutaneous closure of secundum ASD were included in this study. FSO was used in 79 patients, ASO in 42 patients. Pmax and Pd were measured on the surface electrocardiography before and soon after procedure. For comparison of P-wave parameters initially and after procedure paired t-test was used. Correlation analysis was performed using Pearson correlation test. Pmax and Pd were significantly increased immediate after procedure (p<0.001). In FSO and ASO group pre/postprocedural Pd were 38.3 ± 2.7/ 44.1 ± 2.7 msec and 37.5 ± 2.5/ 50.1 ± 2.2 msec respectively. ASO group had a greater postprocedural Pmax and Pd (p<0.001). Left and right atrial disc diameter and device size were the strongest correlates of Pd (r=0.52, p<0.001; r=0.58, p<0.001; r=0.35, p=0.001, respectively). Moderate correlation was found between pre-intervention Pd and age (p=0.008). Pmax and Pd were significantly increased soon after atrial septal defect closure procedure in both devices. Pd is significantly lower in patients closed with FSO device. Difference may be due to the distinctive texture of devices. There was no significant difference in terms of clinically apparent arrhythmia after closure with both device types.

Cardiac Iron Load and Novel P-Wave Measurements in Patients with Thalassemia Major: The role of P index and Interatrial Block

The deleterious effects of cardiac iron load on the ventricular repolarization were demonstrated in beta-thalassemia major (βTM), but little is known about the P wave measurements, an independent risk factor for development of atrial fibrillation (AF). We aimed to examine relationship between P-wave parameters and iron loading using cardiac T2* Magnetic Resonance Imaging (MRI) in asymptomatic β-TM patients. The study involved 22 β-TM patients and 22 age- and gender-matched healthy controls. Although P-wave parameters were within normal limits, P max, P min, and Pi were significantly prolonged in the β-TM group compared to the healthy controls (p=0.005, p=0.01, and p=0.03, respectively). Pd was found similar between groups (p=0.46). The prevalence of partial IAB was increased in patients with β-TM (p=0.001) and complete IAB was detected only in one patient. P-wave parameters of patients with cardiac T2* =20 msec were comparable in patients with β-TM. There was no correlation between P-wave parameters and cardiac T2*MRI values. The present study demonstrated that P-wave measurements were slightly affected in β-TM patients with preserved LV functions and this influence was not related with cardiac T2*MRI values. We concluded that the effect of β-TM on the AF development is still controversial.

Meta‐Analysis of P‐Wave Dispersion Values in Healthy Individuals: The Influence of Clinical Characteristics

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

Electrocardiographic Findings in Patients with Polycythemia Vera

The 12-lead surface electrocardiogram (ECG) is a useful tool to predict both atrial and ventricular arrhythmias via P-wave and QT measurements and its derivatives. Polycythemia vera (PV) is a chronic myeloproliferative disorder associated with cardiovascular events. The aim of this study was to assess ECG findings of patients with PV. Sixty patients with PV (34 male, mean age 58±11 years) and 60 age and gender-matched healthy volunteers were enrolled into the study. From the 12-lead surface ECG, P-wave and both conventional QT measurements and transmyocardial repolarization parameters (T(peak)-T(end) interval (T(p)-T(e)) and derivatives) were evaluated digitally by two experienced cardiologists. In addition, a novel parameter, Pi was calculated digitally as the standard deviation of the P-wave duration across the 12 ECG leads. QT duration and corrected QT interval were significantly longer in the PV group compared to healthy controls (p<0.01 and p<0.01, respectively). The T(p)-T(e) was longer and the T(p)-T(e)/QT ratio was significantly higher in the PV group compared to the controls. P-wave analyses showed that all P-wave parameters including Pmax, Pmin, P dispersion, and Pi were significantly prolonged in PV patients compared to the controls. The increase of both T(p)-T(e )and P max in the PV group was independent of age, BMI, diabetes and hypertension, gender, systolic blood pressure, hemoglobin, hematocrit, left atrial dimension, left ventricular end-diastolic diameter and early deceleration time in a univariate analysis of co-variance model (F=11.097, p=0.001 and F=31.537, p=0.0001, respectively). The present study demonstrated that PV may be associated with electrocardiographic abnormalities of both atrium and ventricle.

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.

Analysis of theD+→K−π+e+νedecay channel

Using 347.5 fb-1 of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244*10^3 signal events for the D+ --> K- pi+ e+ nu_e decay channel are analyzed. This decay mode is dominated by the \bar{K}^*(892)^0 contribution. We determine the \bar{K}^*(892)^0 parameters: m_{K^*(892)^0}=(895.4 +- 0.2 +- 0.2) MeV/c^{2}, \Gamma^0_{K^*(892)^0}=(46.5 +- 0.3 +- 0.2) MeV/c^{2} and the Blatt-Weisskopf parameter $r_{BW}=2.1 +- 0.5 +- 0.5 (GeV/c)^{-1} where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q^{2}=0 (r_{V} = V(0) / A_{1}(0)=1.463 +- 0.017 +- 0.031, r_{2} = A_{2}(0) / A_{1}(0) = 0.801 +- 0.020 +- 0.020) and the value of the axial-vector pole mass parameterizing the q^2 variation of A_{1} and A_{2}: m_{A}=(2.63 +- 0.10 +- 0.13) GeV/c^{2}. The S-wave fraction is equal to (5.79 +- 0.16 +- 0.15)%. Other signal components correspond to fractions below 1%. Using the D+ --> K- pi+ pi+ channel as a normalization, we measure the D+ semileptonic branching fraction: BR(D+ --> K- pi+ e+ nu_e) = (4.04 +- 0.03 +- 0.04 +- 0.09) \times 10^{-2} where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A_1 at q^{2}=0: A_{1}(0) = 0.6226 +- 0.0056 +- 0.0065 +- 0.0074. Fixing the P-wave parameters we measure the phase of the S-wave for several values of the Kpi mass. These results confirm those obtained with Kpi production at small momentum transfer in fixed target experiments.

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

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. 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. P-wave duration was 139 + or - 23 ms and the RMS20 was 1.9 + or - 1.1 microV. 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). 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.

Chronic Carbon Monoxide Exposure Increases Electrocardiographic P-wave and QT Dispersion

We investigated the association between chronic carbon monoxide (CO) exposure and electrocardiographic maximum/minimum P-wave duration (Pmax/Pmin), P-wave dispersion (Pd), maximum/minimum QT interval (QTmax/QTmin), and QT and corrected QT dispersion (QTd/cQTd), which are known as predictors of atrial fibrillation, ventricular arrhythmias, and sudden death. We obtained electrocardiograms of 48 apparently healthy male indoor barbecue workers (age mean ± SD; 33.6 ± 9.4) who were working in various restaurants for at least 3 yr and 51 age-matched healthy men (age mean ± SD; 35.1 ± 6.7). Average working time of the indoor barbecue workers in their jobs was 15.6 ± 7.1 yr. P-wave parameters were analyzable in 39 barbecue workers and 40 control subjects and QT intervals were analyzable in 44 barbecue workers and 47 control subjects. Clinical characteristics of indoor barbecue workers and the control group were comparable in terms of age, sex, body mass index, blood pressure, heart rate, Pmin, and QTmin. However, COHb levels, Pmax, Pd, QTmax, QTd, and cQTd measurements were higher in indoor barbecue workers than in the control group (6.48 ± 1.43 vs. 2.19 ± 1.30, p < .001; 106.15 ± 7.47 vs. 101.50 ± 6.62, p < .005; 30.51 ± 7.59 vs. 24.50 ± 6.77, p < .001; 406.59 ± 17.64 vs. 390.85 ± 13.15, P < .001; 48.40 ± 8.87 vs. 34.89 ± 5.85, P < .001; 53.64 ± 9.14 vs. 37.77 ± 6.71, P < .001, respectively). In Pearson correlation analysis there were significant correlations between COHb level and Pd, QTmax, QTd, and cQTd (r = .315 P < .005; r = .402, P < .001, r = .573, P < .001, r = .615, P < .001, respectively). In conclusion, the present study is the first to assess and find an association between chronic CO exposure and electrocardiographic Pd and QTd/cQTd.

Not Available

P-wave signal averaging is used in an attempt to detect patients at risk of atrial arrhythmias, particularly atrial fibrillation. Although many studies utilized this method, data on the relationship between clinical and echocardiographic variables and signal averaged P-wave parameters are sparse. Thus, we performed a prospective study to evaluate the influence of important clinical and echocardiographic variables on P-wave parameters. The study included 100 probands without demonstrable cardiac disease. P-wave signal averaging was performed after echocardiographic examination in all subjects. Overall P-wave duration averaged 122±16 ms and correlated significantly with age, left atrial and left ventricular end-diastolic diameter on univariate analysis (r=0.287, 0.393 and 0.375; p=0.004, ;0.0001 and ;0.0001, respectively). On multivariate analysis, however, age was the only independent factor affecting signal averaged P-wave duration (p=0.02). There were statistically significant differences in left atrial size and P-wave duration if probands were grouped according to their age. Conclusion There is a significant relationship between signal averaged P-wave duration and age. This may be due to increased atrial fibrosis in elderly subjects. These data should be considered when signal-averaged P wave duration is used as a risk stratifier in patients prone to atrial fibrillation.