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Background: Based on historical studies of leadless pacemakers (LPs), high atrioventricular synchrony (AVS) with mechanical sensing-based VDD pacing is largely influenced by A4 amplitude. A limited study investigated the predictors of A4 amplitude using clinical and echocardiographic parameters., Objective: The purpose of this study was to investigate the predictors of A4 amplitude preoperatively to select patients who could benefit the most from AVS among patients with VDD LPs (Micra-AV, Medtronic)., Methods: Data from patients who received Micra-AV implantations from November 2021 to August 2023 at Tottori University Hospital were analyzed. Twelve-lead electrocardiography and transthoracic echocardiography were performed before the Micra-AV implantations. To assess the electrical indices associated with the A4 signal, electrocardiographic morphologic P-wave parameters were analyzed, including P-wave duration, P-wave amplitude, maximum deflection index (MDI), and P-wave dispersion., Results: A total of 50 patients who underwent Micra-AV implantations (median age 84 years; 64% male) were included and divided into 2 groups based on the median value of A4 amplitude, the high-A4 group (A4 amplitude >2.5 m/s 2 ; n = 26), and low-A4 group (A4 amplitude ≤2.5 m/s 2 ; n = 24). There was a significant difference between the high-A4 and low-A4 groups with regard to left ventricular ejection fraction (P = .01), P-wave dispersion (P = .01), and MDI (P <.001). Multivariate logistic analysis revealed that lower MDI was an independent predictor of high A4-amplitude (odds ratio 0.78; 95% confidence interval 0.67-0.92; P = 0.003)., Conclusion: Preoperative electrocardiographic evaluations of P-wave morphology may be useful for predicting A4 amplitude. MDI was the only independent A4 amplitude predictor that seemed promising for selecting Micra-AV patients., Competing Interests: Disclosures This research was supported by the External Research Program (Grant Number ERP-2022-13342) from Medtronic Japan Co., Ltd. Dr Yamamoto has received lecturer fees from Otsuka Pharmaceutical Co., Ltd., Daiichi-Sankyo Co., Ltd., and Novartis; and research grants from Abbott, Otsuka Pharmaceutical Co., Ltd., Medtronic Japan Co., Ltd., Daiichi-Sankyo Co., Ltd., Boston Scientific Co., Ltd., Biotronik Japan Inc., Japan Lifeline Co., Ltd., Mitsubishi Tanabe Pharma Co., Ltd., Fukuda Denshi, Takeda Pharmaceutical Co., Ltd., Ono Pharmaceutical Co., Ltd., and Novartis. Dr Kato has received research grants from Medtronic Japan Co., Ltd (Grant Number ERP-2022-13342). Dr Okamura has received lecturer fees from Medtronic Japan Co., Ltd. All other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

P-wave dispersion (PWD, Pd or Pdis) is a noninvasive electrocardiographic (ECG) marker for atrial remodeling and predictor for atrial fibrillation (AF). PWD is defined as the difference between the widest and the narrowest P-wave duration recorded from the 12 ECG leads. Increased P-wave duration and PWD reflect prolongation of intraatrial and interatrial conduction time with lack of a well-coordinated conduction system within the atrial muscles, with inhomogeneous, asynchronic, pro-inflammatory and anti-inflammatory effect mediated by interleukin-6 (IL-6) in patients with the CG + GG genotype IL-6 -634C/G polymorphism [1] and discontinuous propagation of sinus impulses mainly between the left and right atria, interstitial/extracellular fibroblast activation and collagen deposition with fibrosis (via TGF-β) in atrial tissue, insufficient blood supply, significant not isotropic myoelectric activity, and thin wall thickness and consequent expansion tendency all well-known electrophysiological characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation (PAF) [2].

Background: Paroxysmal atrial tachyarrhythmias frequently occur in beta-thalassemia major (β-TM) patients.The aim of our study was to investigate the role of maximum P-wave duration (P max) and dispersion (PD), calculated trough a new manually performed measurement with the use of computer software from all 12-ECG-leads, as predictors of atrial-fibrillation (AF)in β-TM patients with conserved systolic or diastolic cardiac function during a twelve-months follow-up. Materials and Methods: 50 β-TM-patients (age38.4±10.1; 38M) and 50-healthy subjects used as controls, matched for age and gender, were studied for the occurrence of atrial arrhythmias during a 1-year follow-up, through ECG-Holter-monitoring performed every three months. The β-TM-patients were divided into two groups according to number and complexity of premature-supraventricular-complexes at the Holter-Monitoring (Group1: 30/h or couplets, or run of supraventricular tachycardia and AF, n:15). Results: Compared to the healthy control-group, β-TM patients presented increased P-max (107.5± 21.2 vs 92.1±11ms, P=0.03) and PD-values (41.2±13 vs 25.1±5 ms, P=0.03). In the β-TM population, the Group2 showed a statistically significant increase in PD (42.8±8.6 vs 33.2±6.5ms, P

OBJETIVO: Analisar comparativamente a dispersão da onda P (DOP) em pacientes com talassemia beta maior (β-TM) e indivíduos saudáveis (controles) para a detecção precoce do risco de arritmias. MÉTODOS: Oitenta e uma crianças com β-TM, com idades entre 4 e 19 anos, e 74 crianças saudáveis (grupo controle) foram submetidas a exame eletrocardiográfico e ecocardiograma transtorácico de rotina para avaliação cardíaca. A DOP foi calculada como a diferença entre as durações máxima e mínima da onda P. RESULTADOS: Houve uma diferença estatisticamente significativa entre o grupo de estudo e o grupo controle no pico de velocidade do fluxo transmitral no início da diástole (E) e na razão E/fluxo transmitral tardio (A). A duração máxima da onda P e a DOP foram significativamente maiores nos pacientes com β-TM do que nos indivíduos controles. CONCLUSÕES: O aumento da DOP em nossos pacientes com β-TM pode estar relacionado à depressão na condução intra-atrial, devido à dilatação atrial, e ao aumento da atividade simpática. Estes pacientes devem ser acompanhados atentamente devido à possibilidade de ocorrência de arritmias com risco de vida.OBJECTIVE: To comparatively evaluate P-wave dispersion (PWD) in patients with β-thalassemia major (TM) and healthy control subjects for the early prediction of arrhythmia risk. METHODS: Eighty-one children with β-TM, aged 4-19 years, and 74 healthy children (control group) underwent routine electrocardiography and transthoracic echocardiography for cardiac evaluation. PWD was calculated as the difference between the maximum and the minimum P-wave duration. RESULTS: There was a statistically significant difference between study and control groups in peak early (E) mitral inflow velocity and E/late (A) velocity ratio. Maximum P-wave duration and PWD were found to be significantly higher in β-TM patients than in control subjects. CONCLUSIONS: Increased PWD in our β-TM patients might be related to depression of intra-atrial conduction due to atrial dilatation and increased sympathetic activity. These patients should be closely followed up for risk of life-threatening arrhythmias.

Atrial fibrillation (AF) is a frequent arrhythmia in patients undergoing hemodialysis (HD). P wave duration (PWdu) and P wave dispersion (PWdi) have been shown to be predictors of emerging AF in different clinical conditions. We sought to study the impact of HD on PWdu, PWdi, and P wave amplitude in a cohort of patients undergoing HD. Seventeen patients (8 men, 31±10 years) were studied. Echocardiography parameters, the sum of the amplitude of P waves in all 12 ECG leads (SP), mean PWdu, and PWdi, along with a host of other parameters (body weight, heart rate, electrolytes and hemoglobin/hematochrit) were measured 1/2h, before and after, HD. SP increased (11.8±3.9 vs 15.3±4.0 mm, p = 0.004), mean PWdu remained stable (82.7±11.1 vs 81.6±10.5 ms, p = 0.606), PWdi decreased (51.7±19.1 vs 41.7±19.1 ms, p = 0.03), and left atrial dimension decreased (37.96±3.90 vs 30.62±3.38 mm, p = 0.0001), after HD. The change in PWdi correlated with fluid removed by HD (r = -0.55, p = 0.022). Re-measurements of P-wave parameters in a random group of 11 of the 17 patients revealed augmented SP (p = 0.01), and stable mean PWdu (p = 0.36), and PWdi (p = 0.31), after HD. Fluid removed by HD leads to an increase in SP, a stable mean PWdu, and decrease (or stability on re-measurement in a subgroup of patients) in PWdi. Stability of PWdu may be due to the effects of augmentation of the P-wave amplitude and the reduction of the left atrial volume, cancelling each other. Variability of PWdi may stem from the occasional impossibility to measure PWdu (or measure it correctly) in minute P-waves in certain ECG leads, which in turn profoundly affects the PWdi.

Background: Attenuation of the P-wave amplitudes in patients with peripheral edema (PERED) has been recently reported, with P-waves regaining some of their amplitude in patients, who subsequently experienced amelioration of their PERED. Changes in the P-waves correlated with the corresponding alterations in the QRS complexes. Also since amplitudes and durations of QRS complexes changed in parallel in patients with PERED, it was hypothesized that similar changes in the P-wave amplitudes, mean P-wave duration (P-du-mean), and P-wave dispersion (P-d), would occur in such patients. Methods: Measurements of P-wave amplitude, P-du-mean and P-d in patients who developed, or experienced alleviation, of PERED, were carried out and analyzed. Results: Although P-wave amplitudes and P-wave areas decreased with development of PERED (N = 16), and increased with its amelioration (N = 6), P-dur-mean before PERED was 66.8±14.5 ms, and at peak weight gain it was 65.2±11.9 ms, p = 0.66; also at peak weight gain and subsequent lowest weight, in the patients who lost weight, it was 66.5±9.9 ms and 72.3±12.0 ms, respectively, p = 0.38. Similarly the P-d prior to PERED was 62.3±25.2 ms, and at peak weight gain it was 74.3±29.3 ms, p = 0.09; also at peak weight and subsequent lowest weight, in the patients who lost weight, it was 58.8±34.2 ms, and 61.3±13.6 ms, respectively, p = 0.87. Conclusions: P-du-mean and P-d did not change in patients who developed PERED; their stability is attributed to the offsetting of the electrophysiologically-mediated real changes, by opposite apparent changes, imparted by PERED.

Background: Mitral stenosis (MS) is associated with prolonged inter- and intra-atrial electromechanical delays and increased P-wave dispersion, which are markers of atrial fibrillation (AF) risk. This study was conducted to assess the immediate effect of successful percutaneous transvenous mitral commissurotomy (PTMC) on these parameters. Methods: This single center observational study included 25 patients with severe MS (aged 34.1 ± 7.1 years, with mean mitral valve area (MVA) of 0.74 ± 0.13 cm2), in sinus rhythm, who underwent successful PTMC at our hospital. P-wave dispersion (PWD) was calculated by subtracting minimum P-wave duration (Pmin) from maximum P-wave duration (Pmax), measured on a 12-lead surface ECG obtained from each patient in supine position at a paper speed of 50 mm/s and 20 mm/mV. Inter-atrial (AEMD), left intra-atrial (L-IAEMD), and right intra-atrial (R-IAEMD) electromechanical delays were measured on tissue Doppler imaging. PTMC was performed using the standard Inoue Balloon technique. All these parameters were evaluated and compared before and 24–48 h after PTMC. Results: Successful PTMC led to significant reduction in AEMD (p

Well-known difficulties in defining P-wave onset and offset may restrict the accuracy and reproducibility of P-wave dispersion measurements. To achieve greater precision in measuring P-wave dispersion, simultaneous digital recording of all 12 ECG leads and onscreen measurement of P wave characteristics is mandatory to examine atrial fibrillation risk.

Objectives: Diabetes mellitus is an independent and strong risk factor for development of atrial fibrillation (AF). Electrophysiologic and electromechanical abnormalities are associated with a higher risk of AF. In this study we aimed to determine the correlation of atrial conduction abnormalities between the surface electrocardiographic and tissue Doppler echocardiographic measurements in type 2 diabetes mellitus (T2DM) patients., Methods: A total of 88 consecutive T2DM patients and 49 age-, gender-, and body mass index-matched healthy volunteers were included in the present study. Baseline characteristics were recorded and 24-hour ambulatory blood pressure monitoring, transthoracic echocardiography, and 12-lead surface electrocardiography were performed for all study participants. Atrial electromechanical delay (EMD) intervals were measured., Results: Maximum P-wave duration and P-wave dispersion (Pd) were significantly higher in patients with T2DM (105.7±10.2ms vs. 102.2±7.5ms, p=0.02; 40.6±7.6ms vs. 33.6±5.9ms, p<0.001, respectively). Interatrial, intraatrial, and intraleft atrial EMD were significantly higher in the T2DM patients when compared with the controls (16.5±7.8ms vs.11.2±4.4ms, p<0.001; 9.0±7.3ms vs. 6.0±3.8ms, p=0.002, and 7.4±5.2ms vs. 5.1±3.2ms, p=0.002 respectively). Correlation analysis showed a positive correlation between interatrial EMD and Pd (r=0.429, p<0.001) and left atrial volume (r=0.428, p<0.001)., Conclusions: In this study, there was significant EMD and Pd in patients with T2DM as compared with healthy volunteers. Additionally, interatrial EMD was correlated with Pd and left atrial volume index., (Copyright © 2015 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.)

Background: Metabolic syndrome (MS) is an important risk factor for atrial fibrillation. P-wave indices, including P-wave dispersion (PWD) and P-wave duration, can be used as non-invasive markers of heterogeneous atrial conduction. The aim of our study was to evaluate the relationship between P-wave indices and insulin resistance in patients with MS., Methods: Seventy-four patients with MS (44 men, 30 women) and 81 patients without MS (48 men, 33 women) were enrolled in the study. A diagnosis of MS was made as defined by the Adult Treatment Panel III of the National Cholesterol Education Program. Insulin resistance was estimated using the homeostasis model assessment (HOMA) index. P-wave maximum duration (Pmax) and P-wave minimum duration (Pmin) were calculated on a 12-lead electrocardiogram, and the difference between the Pmax and the Pmin was defined as PWD., Results: Patients with MS had a longer PWD and a higher Pmax compared with patients without MS (PWD, 35.65±4.36 vs. 26.27±4.04, P<0.001; Pmax, 117.12±10.77 vs. 105.98±9.02, P<0.001), whereas no difference was found between Pmin values from MS patients and controls (81.47±9.54 vs. 79.70±8.76, P=0.231). Stepwise multivariate analysis revealed only the HOMA index to be an independent predictor of PWD (β=3.115, P<0.001) and Pmax (β=7.175, P<0.001)., Conclusion: This study suggests that patients with MS have a prolonged PWD and Pmax. The increase in these parameters may be an indicator for identification of patients at an increased risk for atrial fibrillation., (Copyright © 2014. Published by Elsevier Masson SAS.)

Purpose: Late-onset atrial arrhythmia after successful closure of atrial septal defect (ASD) is not uncommon. Right atrial (RA) enlargement and increased electrocardiographic P-wave dispersion (Pd) independently predict the development of atrial arrhythmia. Data on the degree of right atrial (RA) geometrical and electrical remodeling following device closure of ASD are limited., Methods: Echocardiography and electrocardiography (ECG) were performed in 58 consecutive patients (47 ± 17 years) before and at 3 months after ASD closure. Persistent RA enlargement was defined as RA volume index (RAVI) ≥ 21 ml/m(2) at 3 months. Pd was calculated as the difference between maximal and minimal P-wave durations in 12-lead ECG., Results: RA size reduced (RAVI: 50 ± 28 vs. 26 ± 16 ml/m(2), p<0.001) and Pd on ECG decreased (53 ± 17 vs. 49 ± 20 ms, p<0.05) significantly at 3 months when compared to baseline. However, persistent RA enlargement remained evident in 31 patients (53%). As a group, they were older with higher pulmonary arterial systolic pressure, larger Qp/Qs, longer maximal P-wave duration and Pd than those with normalized RA. Pd reduction only occurred in patients with normalized RA size. The 3-month Pd (hazard ratio: 1.033, p<0.001) predicted the presence of incomplete RA geometrical remodeling. ROC curve revealed that Pd ≥ 45 ms at 3 months was 77% sensitive and 86% specific in revealing residual RA enlargement., Conclusion: Both atrial geometrical and electrical reverse remodeling were evident at 3 months following ASD closure. However, only half of the included patients had normalization of RA size which could be revealed by a simple ECG surrogate of intra-atrial conduction disturbance., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)