Multilevel transcrustal magmatic system beneath the Geysers-Clear Lake area.

Magmatism in the Quaternary Clear Lake volcanic field (CLVF), with its youngest eruption having only occurred c. 10 ka ago, is commonly invoked as the heat source for the world's largest commercial geothermal reservoir, The Geysers, in northern California. A shallow silicic magma reservoir in the upper-middle crust has been discovered for some time, but the location and mechanism of a potential deep mafic magma reservoir have remained elusive. Here, we present a seismic tomographic model that images the entire crustal column, clearly revealing a multilevel transcrustal magmatic system beneath the Geysers-Clear Lake area. Upwelling melts from the mantle traverse across the crust-mantle boundary and accumulate in the lower crust underneath the southeastern part of Clear Lake, resulting in a hot Moho in between. Mafic melts primarily ascend westward due to the extensional regime in the west and physical barrier effect from the overlying rigid ophiolite fragment, ultimately forming a shallow silicic magma reservoir underlying and heating The Geysers geothermal field. In addition, this study also links compositionally diverse volcanism in a continental setting to differentiation in a multilevel transcrustal magmatic system.

P-wave alternans rebound following pulmonary vein isolation predicts atrial arrhythmia recurrence.

INTRODUCTION: Numerous P-wave indices have been explored as biomarkers to assess atrial fibrillation (AF) risk and the impact of therapy with variable success. OBJECTIVE: We investigated the utility of P-wave alternans (PWA) to track the effects of pulmonary vein isolation (PVI) and to predict atrial arrhythmia recurrence. METHODS: This medical records study included patients who underwent PVI for AF ablation at our institution, along with 20 control subjects without AF or overt cardiovascular disease. PWA was assessed using novel artificial intelligence-enabled modified moving average (AI-MMA) algorithms. PWA was monitored from the 12-lead ECG at ~1 h before and ~16 h after PVI (n = 45) and at the 4- to 17-week clinically indicated follow-up visit (n = 30). The arrhythmia follow-up period was 955 ± 112 days. RESULTS: PVI acutely reduced PWA by 48%-63% (p < .05) to control ranges in leads II, III, aVF, the leads with the greatest sensitivity in monitoring PWA. Pre-ablation PWA was ~6 µV and decreased to ~3 µV following ablation. Patients who exhibited a rebound in PWA to pre-ablation levels at 4- to 17-week follow-up (p < .01) experienced recurrent atrial arrhythmias, whereas patients whose PWA remained reduced (p = .85) did not, resulting in a significant difference (p < .001) at follow-up. The AUC for PWA's prediction of first recurrence of atrial arrhythmia was 0.81 (p < .01) with 88% sensitivity and 82% specificity. Kaplan-Meier analysis estimated atrial arrhythmia-free survival (p < .01) with an adjusted hazard ratio of 3.4 (95% CI: 1.47-5.24, p < .02). CONCLUSION: A rebound in PWA to pre-ablation levels detected by AI-MMA in the 12-lead ECG at standard clinical follow-up predicts atrial arrhythmia recurrence.

Unusual atrial pacing induced by type II far-field p-wave sensing in a patient with complete atrioventricular block.

An 88-year-old Japanese woman underwent DDD pacemaker (MicroPort KORA 250 DR, V lead: VEGA R52) implantation for complete atrioventricular block. A 12-lead electrocardiogram for a routine examination showed atrial pacing within the intrinsic P wave, followed by inhibition of ventricular pacing. Pacemaker interrogation revealed no abnormalities in the basic parameters; however, ventricular pacing was inhibited by far-field sensing of intrinsic atrial waves before atrial events; type II far-field P-wave sensing. As a result, unusual atrial pacing occurred due to the pause suppression algorithm, which is the one of the functions that prevent atrial fibrillation development.

Predictors of atrial fibrillation after embolic stroke of undetermined source in patients with implantable loop recorders.

BACKGROUND: In patients with embolic stroke of undetermined source (ESUS), underlying subclinical atrial fibrillation (AF) is often suspected. Previous studies identifying predictors of AF have been limited in their ability to diagnose episodes of AF. Implantable loop recorders enable prolonged, continuous, and therefore more reliable detection of AF. The aim of this study was to identify clinical and ECG parameters as predictors of AF in ESUS patients with implantable loop recorders. METHODS: 101 ESUS patients who received an implantable loop recorder between 2012 and 2020 were included in this study. Patients were followed up regularly on a three-monthly outpatient interval. RESULTS: During a mean follow-up of 647 ± 385 days, AF was detected in 26 patients (26%). Independent risk factors of AF were age ≥ 60 years (HR 2.753, CI 1.129-6.713, p = 0.026), P-wave amplitude in lead II ≤ 0.075 mV (HR 3.751, CI 1.606-8.761, p = 0.002), and P-wave duration ≥ 125 ms (HR 4.299, CI 1.844-10.021, p < 0.001). In patients without risk factors, the risk of developing AF was 16%. In the presence of one risk factor, the probability increased only slightly to 18%. With two or three risk factors, the risk of AF increased to 70%. CONCLUSION: AF was detected in about one in four patients after ESUS in this study. A comprehensive evaluation involving multiple parameters and the existence of multiple risk factors yields the highest predictive accuracy for detecting AF in patients with ESUS.

P-wave terminal force is related to left pulmonary vein reconnection in patients with atrial fibrillation recurrence after pulmonary vein isolation.

In patients with atrial fibrillation (AF) recurrence after pulmonary vein (PV) isolation, noninvasive markers predicting PV reconnection or PV reconnection sites have not been fully elucidated. This study investigated the relationship between the P-wave terminal force in lead V1 (PTFV1) and the PV reconnection or reconnection site in patients with AF recurrence. We retrospectively studied consecutive patients who underwent second AF ablation between April 1, 2018, and June 1, 2023. PTFV1 was investigated before the first AF ablation (pre-ablation PTFV1) and before the second AF ablation (post-ablation PTFV1). In addition, we examined the ratio of the post-ablation to pre-ablation PTFV1 (PTFV1 ratio). These values were compared between patients with and without PV reconnection, with and without left PV (LPV) reconnection, and with and without right PV (RPV) reconnection. The analysis included 56 patients. PTFV1 was reduced because of the first AF ablation. In addition, the values were more decreased in patients without PV reconnection than with PV reconnection. The PTFV1 ratio was significantly smaller in the patients without LPV reconnection than with LPV reconnection; no significant difference was observed between the patients with and without RPV reconnection. Receiver operating characteristic curve analysis showed that a PTFV1 ratio > 0.69 predicted LPV reconnection with 70.0% sensitivity and 66.7% specificity. In conclusion, the PTFV1 ratio may be a noninvasive marker predicting LPV reconnection in patients with AF recurrence.

Atrial electrical remodeling and function after transcatheter aortic valve replacement in patients with aortic stenosis.

To examine reverse atrial electrical remodeling in patients with aortic stenosis (AS) after trans-catheter aortic valve replacement (TAVR). In 65 consecutive patients with severe AS (83 ± 4 years, 47 (72.3%) females), we analyzed ECG records for the P wave duration (PWD) in lead II and P-terminal force (PTFV1) in V1, and measured cardiac dimensions and function by echocardiography (ECHO) following TAVR. Biomarkers were measured to assess myocardial injury by TAVR. TAVR was successfully performed without major complications: the aortic valve area increased from 0.62 ± 0.14 cm2 to 1.52 ± 0.24cm2, and the trans-aortic pressure gradient decreased from 58.4 ± 15.9 mmHg to 15.0 ± 19.6 mmHg. PWD and PTFV increased immediately after TAVR and returned to the pre-TAVR levels on the next day. Then, the PWD declined toward 6 months after TAVR non-significantly in all patients, but significantly in 25 patients with baseline PWD ≥ 130 ms (P = 0.039). PTFV1 showed no long-term change. Improvement was observed in the ejection fraction, all thickness of the left ventricle and in the left atrial dimensions on ECHO. After recovery from transient aggravation by TAVR procedure, PWD reversed slowly, and the change was significant in those with baseline PWD ≥ 130 ms while change in PTFV1 was not significant at 6 months of follow-up. ECHO showed a reversal of remodeling in the left ventricle and in the left atrial dimension after TAVR.

Prognostic significance of ratio of P-wave duration to P-wave vector magnitude for mortality in acute anterior myocardial infarction.

BACKGROUND: The impact of P-wave abnormality in acute anterior MI, where the culprit vessel is the left anterior descending artery, remains undetermined. This study aimed to elucidate the impact of P-wave morphology on clinical outcomes in acute anterior MI. METHODS: Patients undergoing emergent percutaneous coronary intervention for acute anterior MI were enrolled between September 2014 and April 2019 (derivation cohort) and May 2019 through July 2023 (validation cohort). P-wave duration (Pd) and P-wave vector magnitude (Pvm) were measured. The Pvm was calculated as the square root of the sum of the squared P-wave magnitudes in leads II and V6 and one-half of the P-wave amplitude in V2. The patients were categorized into high and low Pd/Pvm groups using a statistically derived cut-off value. The endpoint comprised the composite of heart failure (HF) hospitalization and all-cause death. RESULTS: Consecutive 426 patients were enrolled in this study (derivation cohort, 213 patients; validation cohort, 216 patients). The calculated cut-off value of Pd/Pvm for predicting the clinical endpoint, determined through receiver operating curve analysis, was 793.5 ms/mV (area under the curve [AUC] = 0.85, sensitivity of 73.8 %, and specificity of 94.0 %) in the derivation cohort. Kaplan-Meier analyses revealed a significantly higher risk of the endpoint in patients with high Pd/Pvm than those with low Pd/Pvm in derivation and validation cohorts (Log-rank p < 0.001 and p < 0.001, respectively). Multivariate Cox proportional hazards analysis identified advanced age, elevated Pd/Pvm, and reduced left ventricular ejection fraction as independent and significant factors associated with the endpoint in the validation cohort (p = 0.008, p < 0.001, and p < 0.001, respectively). CONCLUSION: High Pd/Pvm was significantly associated with the composite of HF hospitalization and all-cause death after acute anterior MI.

P-wave characteristics as electrocardiographic markers of atrial abnormality in prediction of incident atrial fibrillation - The Malmö Preventive Project.

BACKGROUND: P-wave indices reflect atrial abnormalities contributing to atrial fibrillation (AF). We aimed to assess a comprehensive set of P-wave characteristics for prediction of incident AF in a population-based setting. METHODS: Malmö Preventative Project (MPP) participants were reexamined in 2002-2006 with electrocardiographic (ECG) and echocardiographic examinations and followed for 5 years. AF-free subjects (n = 983, age 70 ± 5 years, 38% females) with sinus rhythm ECGs were included in the study. ECGs were digitally processed using the Glasgow algorithm. P-wave duration, axis, dispersion, P-terminal force in lead V1 and interatrial block (IAB) were evaluated. ECG risk score combining the morphology, voltage and length of P-wave (MVP score) was calculated. New-onset diagnoses of AF were obtained from nation-wide registers. RESULTS: During follow up, 66 patients (7%) developed AF. After adjustment for age and gender, the independent predictors of AF were abnormal P-wave axis > 75° (HR 1.63 CI95% 1.95-11.03) and MVP score 4 (HR 6.17 CI 95% 1.76-21.64), both correlated with LA area: Person r - 0.146, p < 0.001 and 0.192, p < 0.001 respectively. Advanced IAB (aIAB) with biphasic P-wave morphology in leads III and aVF was the most prevalent variant of aIAB and predicted AF in a univariate model (HR 2.59 CI 95% 1.02-6.58). CONCLUSION: P-wave frontal axis and MVP score are ECG-based AF predictors in the population-based cohort. Our study provides estimates for prevalence and prognostic importance of different variants of aIAB, providing a support to use biphasic P-wave morphology in lead aVF as the basis for aIAB definition.

Interrelationships among abnormal P-wave axis, metabolic syndrome and its components, and mortality in US adults.

BACKGROUND: Metabolic syndrome (MetS) is associated with increased rates of cardiovascular disease and mortality and is linked to abnormal electrocardiogram (ECG) parameters. We aimed to explore the relationships and interactions among MetS and its components, abnormal P-wave axis (aPWA), and mortality rates. METHODS: We analyzed data from 7526 adult participants with sinus rhythm recruited from the National Health and Nutrition Examination Survey III. MetS was classified based on the NCEP ATP III-2005 definition. aPWA included all P-wave axis outside 0-75°. The National Death Index was utilized to identify survival status. Hazard ratios (HRs) and 95% confidence intervals (CIs) categorized by aPWA, MetS, and their components were analyzed using Cox proportional hazards models to investigate all-cause and cardiovascular mortalities. RESULTS: Within a median follow-up period of 20.76 years, 4686 deaths were recorded, of which 1414 were attributable to cardiovascular disease. Participants with both MetS and aPWA had higher all-cause (HR: 1.45, 95% CI: 1.29-1.64, interaction P = 0.043) and cardiovascular (HR: 1.36, 95% CI: 1.02-1.79, interaction P-value = 0.058) mortality rates than participants without MetS and with a normal P-wave axis. Participants with the greatest number of MetS components and aPWA had a higher risk of all-cause mortality (HR: 1.70, 95% CI: 1.13-2.55, P = 0.011). CONCLUSIONS: Individuals with both aPWA and MetS have a higher risk of mortality, and those with a greater number of MetS components and aPWA have a higher risk of all-cause mortality. These findings highlight the significance of integrating ECG characteristics with metabolic health status in clinical assessment.

Construction of a predictive model for new-onset atrial fibrillation after acute myocardial infarction based on P-wave amplitude in lead V1.

BACKGROUND: In this study, we aimed to identify the risk factors for new-onset atrial fibrillation (NOAF) after postcoronary intervention in patients with acute myocardial infarction (AMI) and to establish a nomogram prediction model. METHODS: The clinical data of 506 patients hospitalized for AMI from March 2020 to February 2023 were retrospectively collected, and the patients were randomized into a training cohort (70%; n = 354) and a validation cohort (30%; n = 152). Independent risk factors were determined using least absolute shrinkage and selection operator and multivariate logistic regression. Predictive nomogram modeling was performed using R software. Nomograms were evaluated based on discrimination, correction, and clinical efficacy using the C-statistic, calibration plot, and decision curve analysis, respectively. RESULTS: The multivariate logistic regression analysis showed that P-wave amplitude in lead V1, age, and infarct type were independent risk factors for NOAF, and the area under the receiver operating characteristic curve of the training and validation sets was 0.760 (95% confidence interval [CI] 0.674-0.846) and 0.732 (95% CI 0.580-0.883), respectively. The calibration curves showed good agreement between the predicted and observed values in both the training and validation sets, supporting that the actual predictive power was close to the ideal predictive power. CONCLUSIONS: P-wave amplitude in lead V1, age, and infarct type were independent risk factors for NOAF in patients with AMI after intervention. The nomogram model constructed in this study can be used to assess the risk of NOAF development and has some clinical application value.

Deep terminal negative of the P wave in V1 and incidence of ischemic stroke: The atherosclerosis risk in communities (ARIC) study.

BACKGROUND: Deep terminal negative of the P wave in V1 (DTNPV1) is a marker of left atrial remodeling. We aimed to evaluate the association of DTNPV1 with incident ischemic stroke. METHODS: The Atherosclerosis Risk in Communities study is a prospective community-based cohort study. All participants at visit 4 (1996-1998) except those with prevalent stroke, missing covariates, and missing or uninterpretable ECG were included. DTNPV1 was defined as the absolute value of the depth of the terminal negative phase >100 µV in the presence of biphasic P wave in V1. Association between DTNPV1 as a time-dependent exposure variable and incident ischemic stroke was evaluated. The accuracy of the prediction model consisting of DTNPV1 and CHA2DS2-VASc variables in predicting ischemic stroke was analyzed. RESULTS: Among 10,605 participants (63 ± 6 years, 56% women, 20% Black), 803 cases of ischemic stroke occurred over a median follow-up of 20.19 years. After adjusting for demographics, DTNPV1 was associated with an increased risk of stroke (HR 1.96, [95% CI 1.39-2.77]). After further adjusting for stroke risk factors, use of aspirin and anticoagulants, and time-dependent atrial fibrillation, DTNPV1 was associated with a 1.50-fold (95% CI 1.06-2.13) increased risk of stroke. When added to the CHA2DS2-VASc variables, DTNPV1 did not significantly improve stroke prediction as assessed by C-statistic. However, there was improvement in risk classification for participants who did not develop stroke. CONCLUSION: DTNPV1 is significantly associated with higher risk of ischemic stroke. Since DTNPV1 is a simplified electrocardiographic parameter, it may help stroke prediction, a subject for further research.

Association between body mass index and electrocardiogram indices: A Mendelian randomization study.

INTRODUCTION: Cardiovascular diseases (CVDs) remain a global health concern, and body mass index (BMI) is known to be associated with an increased risk of CVD, but the exact mechanisms underlying this relationship remain unclear. This study employs Mendelian randomization (MR) to investigate the causal association between BMI and electrocardiogram (ECG) indices, providing insights into potential pathways linking obesity to CVD. METHODS: We conducted a comprehensive MR study utilizing large-scale genetic and ECG data from diverse populations. Instrumental variables were selected from genome-wide association studies, ensuring their relevance to BMI. Causal relationships between BMI and ECG indices, including P wave duration, PR interval, QRS duration, and QT interval, were assessed using various MR methods, with inverse variance weighted (IVW) considered as the primary analysis. RESULTS: Our MR analysis revealed a significant positive causal association between higher BMI and P wave duration (ß = 8.078, 95% CI: 5.322 to 10.833, p < 0.001), suggesting a potential mechanism through which higher BMI may contribute to arrhythmogenic risks. However, no significant causal associations were observed between BMI and PR interval, QRS duration, or QT interval (all p > 0.005). In addition, our study also found that there is no horizontal pleiotropy between BMI and P wave duration, PR interval, QRS duration, and QT interval, suggesting that the conclusions of this study are robust. CONCLUSION: This study supports a causal relationship between elevated BMI and prolonged P wave duration, a marker of increased atrial arrhythmogenic risk. Further investigations are still needed to elucidate the underlying mechanisms.

Advanced Interatrial block induced by flecainide.

We present a case of advanced interatrial block induced by flecainide toxicity. We discuss the implications of this conduction abnormality.

Electrocardiographic frontal QRS-T angle is independently associated with panic disorder.

OBJECTIVE: Panic disorder (PD) may cause serious cardiac arrhythmias by causing electrical abnormalities. Abnormal P-wave axis (aPwa), presence of fragmented QRS (fQRS), wide frontal QRS-T angle (fQRSTa), QRS duration corrected (QRSdc) and log/ logQRS duration/RR interval (log/logQRS/RR) have been correlated with increased risk of serious supraventricular and ventricular cardiac arrhythmias in a general population. The purpose of this study was to compare these newly explored atrial and ventricular arrhythmia indicators in patients with PD and in healthy subjects. METHOD: A total of 169 newly diagnosed PD patients and 128 healthy subjects were included in the study. The Panic and Agoraphobia Scale (PAS) was administered, and 12-lead electrocardiography (ECG) measurements were obtained. Electrocardiographic parameters including aPwa, fQRSTa, presence of fQRS, QRS duration corrected (QRSdc), and log/logQRS duration/RR distance (log/logQRS/RR) were compared between the two groups. RESULTS: aPwa and fQRS, in addition to fQRSTa, QRSdc, and log/ logQRS/RR ratio values, were significantly increased in the PD group compared to healthy controls. Correlation analyses revealed that wider fQRSTa, number of fQRS derivation, number of total fQRS, wider QRSdc, and log/logQRS/RR ratio significantly correlated with PAS score. Logistic regression analysis demonstrated that fQRSTa and the number of total fQRS were independently associated with PD. CONCLUSION: PD is associated with wider fQRSTa, QRSdc, and log/logQRS/RR in addition to the increased abnormal aPwa and presence of fQRS. These findings suggest that untreated PD patients may be susceptible to supraventricular and ventricular arrhythmia, indicating that ECG should be routinely obtained in the management of PD patients.

Advanced Interatrial Block across the Spectrum of Renal Function.

Background and Objective: Interatrial block (IAB) is defined as a conduction delay between the right and left atria. No data are available about the prevalence of both partial IAB and advanced IAB among the different stages of chronic kidney disease. The aim of this study was to describe the prevalence and type of advanced IAB across the spectrum of renal function, including patients on dialysis and the clinical characteristics associated with advanced IAB. Materials and Methods: Retrospective, single-center study of 151 patients consecutively admitted to the Nephrology and Ophthalmology Unit for 3 months. The study population was divided into three groups according to stages of chronic kidney disease. We evaluated the prevalence and pattern of IAB among the groups and the clinical characteristics associated with advanced IAB. Results: The prevalence of partial IAB was significantly lower in end-stage kidney disease (ESKD) group compared to control group (36.7% vs. 59.6%; p = 0.02); in contrast the prevalence of advanced IAB was significantly higher in both chronic kidney disease (CKD) (17.8% vs. 5.3%, p = 0.04) and ESKD group (24.5% vs. 5.3%, p = 0.005) compared to control group. The atypical pattern of advanced IAB was more frequent in both the ESKD and CKD group than in the control group (100% and 75% vs. 33.3%; p = 0.02). Overall, among patients that showed advanced IAB, 17 (73.9%) showed an atypical pattern by morphology and 2 (8.7%) showed an atypical pattern by duration of advanced IAB. The ESKD group was younger than the control group (65.7 ± 12.3 years vs. 71.3 ± 9.9 years; p = 0.01) and showed a higher prevalence of beta blockers (42.9% vs. 19.3%; p = 0.009), as in the CKD group (37.8% vs. 19.3%; p= 0.04). Conclusions: The progressive worsening of renal function was associated with an increasing prevalence of advanced IAB. Advanced IAB may be a sign of uremic cardiomyopathy and may suggest further evaluation with long-term follow-up to investigate its prognostic significance in chronic kidney disease.

[MVP Risk score and new atrial fibrillation diagnosis: Prospective cohort PREFATE study]. / MVP Risk score y nuevo diagnóstico de fibrilación auricular: estudio de cohorte prospectivo PREFATE.

OBJECTIVE: To assess the association between electrocardiogram (ECG) patterns according to the MVP ECG risk score (morphology-voltage-P-wave duration) and a diagnosis of Atrial Fibrillation (AF). DESIGN: Prospective observational cohort study (1/01/2023-31/12/2024). SITE: Primary care. PARTICIPANTS: Randomized sample of 150 patients aged 65-85 years without prior diagnosis of AF, stroke, or current anticoagulant treatment; high risk of future AF; CHA2DS2-VASc ≥2; and ability to use the FibricheckR application (App). MEASUREMENTS: At baseline, a standard ECG, MVP risk score assessment, and cardiac rhythm monitoring for 15 days using the FibricheckR App were performed. The dependent variables were the presence of P-wave patterns on the electrocardiogram according to MVP risk score and a new diagnosis of AF. RESULTS: The diagnosis of AF was confirmed in 14 cases (9.3%, 95% CI 5.6-15.1), 3 men and 11 women. In 3 cases, the arrhythmia was diagnosed on the baseline ECG, and in 11 cases by Holter after being reported as possible AF by the FibricheckR App. A higher prevalence of atypical advanced interatrial block (A-AIB) (p 0.007) was detected among participants with AF, as well as the prevalence of P-wave <0.1mV. (p=0.006). All new diagnoses of AF were made at scores ≥4 in the MVP risk score. CONCLUSIONS: Using scales for identifying ECG patterns in high-risk subjects in primary care can facilitate the diagnosis of unknown AF.

Left atrial epicardial adipose tissue exacerbates electrical conduction disturbance in normal-weight patients undergoing pulmonary vein isolation for atrial fibrillation.

INTRODUCTION: Epicardial adipose tissue (EAT) exacerbates both electrical and structural remodeling in obese atrial fibrillation (AF) patients, but the impacts of EAT on atrial arrhythmogenicity remain unclear in normal-weight AF patients. Therefore, we sought to investigate this issue using electroanatomic mapping. METHODS AND RESULTS: We enrolled drug-refractory 105 paroxysmal AF patients in the normal body mass index range (18.5-24.9 kg/m2 ), who had undergone electroanatomic mapping after pulmonary vein isolation (PVI). One day before PVI, we assessed P-wave duration in a 12-lead electrocardiogram and left atrial (LA)-EAT volumes using contrast-enhanced computed tomography. The patients were divided into two groups based on the median LA-EAT volume (16.0 ml); the high LA-EAT group (≥16.0 ml, n = 53) and low LA-EAT group (<16.0 ml, n = 52). We compared P-wave duration, LA conduction velocity and bipolar voltage, the presence of low-voltage zone (<0.5 mV), and LA volume index on echocardiography between the two groups. The LA bipolar voltage, low-voltage zone, and LA volume index were not different between the high and low LA-EAT groups. However, P-wave duration was significantly longer in the high group than in the low group (p < .001). Additionally, the LA conduction velocity was significantly more depressed in the high group than in the low group (p < .001). Multivariate linear regression analysis revealed that LA-EAT volume was correlated with P-wave duration (ß = .367, p < .001) and conduction velocity (ß = -.566, p < .001), respectively. CONCLUSIONS: Increased LA-EAT volumes were associated with electrical conduction disturbance after PVI in normal-weight patients with AF. P-wave duration may be a clinically useful predictor of LA-EAT.

Electrocardiographic markers of subclinical atrial fibrillation detected by implantable loop recorder: insights from the LOOP Study.

AIMS: Insights into subclinical atrial fibrillation (AF) development are warranted to inform the strategies of screening and subsequent clinical management upon AF detection. Hence, this study sought to characterize the onset and progression of subclinical AF with respect to 12-lead electrocardiogram (ECG) parameters. METHODS AND RESULTS: We included AF-naïve individuals aged 70-90 years with additional stroke risk factors who underwent implantable loop recorder (ILR) monitoring in the LOOP Study. Using data from daily ILR recordings and the computerized analysis of baseline ECG, we studied empirically selected ECG parameters for AF detection (≥6 min), cumulative AF burden, long-lasting AF (≥24 h), and AF progression. Of 1370 individuals included, 419 (30.6%) developed AF during follow-up, with a mean cumulative AF burden of 1.5% [95% CI: 1.2-1.8]. Several P-wave-related and ventricular ECG parameters were associated with new-onset AF and with cumulative AF burden in AF patients. P-wave duration (PWD), P-wave terminal force in Lead V1, and interatrial block (IAB) further demonstrated significant associations with long-lasting AF. Among AF patients, we observed an overall reduction in cumulative AF burden over time (IRR 0.70 [95% CI: 0.51-0.96]), whereas IAB was related to an increased risk of progression to AF ≥24 h (HR 1.86 [95% CI: 1.02-3.39]). Further spline analysis also revealed longer PWD to be associated with this progression in AF duration. CONCLUSION: We identified several ECG parameters associated with new-onset subclinical AF detected by ILR. Especially PWD and IAB were robustly related to the onset and the burden of AF as well as progression over time.

Association of electrocardiographic spatial heterogeneity of repolarization and spatial heterogeneity of atrial depolarization with left ventricular fibrosis.

AIMS: To evaluate the relationship between spatial heterogeneity of electrocardiographic repolarization and spatial heterogeneity of atrial depolarization with arrhythmic substrate represented by left ventricular fibrosis. METHODS AND RESULTS: We assessed the associations of T- and P-wave morphology parameters analysed from the standard 12-lead electrocardiograms with left ventricular fibrosis in 378 victims of unexpected sudden cardiac death (SCD) who underwent medico-legal autopsy. Based on autopsy findings, the SCD victims were categorized into four different groups according to different stages of severity of left ventricular fibrosis (substantial fibrosis, moderate patchy fibrosis, scattered mild fibrosis, no fibrosis). T-wave and P-wave area dispersion (TWAd: 0.0841 ± 0.496, 0.170 ± 0.492, 0.302 ± 404, 0.296 ± 0.476, P = 0.008; PWAd: 0.574 ± 0.384, 0.561 ± 0.367, 0.654 ± 0.281, 0.717 ± 0.257, P = 0.011, respectively; low values abnormal), non-dipolar components of T-wave and P-wave morphology (T_NonDipolarABS: 0.0496 ± 0.0377, 0.0571 ± 0.0487, 0.0432 ± 0.0476, 0.0380 ± 0.0377, P = 0.027; P_NonDipolarABS: 0.0132 ± 0.0164, 0.0130 ± 0.0135, 0.0092 ± 0.0117, 0.0069 ± 0.00472, P = 0.005, respectively, high values abnormal), T-wave morphology dispersion (TMD: 45.9 ± 28.3, 40.5 ± 25.8, 35.5 ± 24.9, 33.0 ± 24.6, P = 0.030, respectively, high values abnormal), and P-wave heterogeneity (PWH: 20.0 ± 9.44, 19.7 ± 8.87, 17.9 ± 9.78, 15.4 ± 4.60, P = 0.019, respectively, high values abnormal) differed significantly between the groups with different stages of left ventricular fibrosis. After adjustment with heart weight, T_NonDipolarABS [standardized ß (sß) = 0.131, P = 0.014], PWAd (sß = -0.161, P = 0.003), P_NonDipolarABS (sß = 0.174, P = 0.001), and PWH (sß = 0.128, P = 0.015) retained independent association, and TWAd (sß = -0.091, P = 0.074) and TMD (sß = 0.097, P = 0.063) tended to retain their association with the degree of myocardial fibrosis. CONCLUSION: Our findings suggest that abnormal values of T- and P-wave morphology are associated with arrhythmic substrate represented by ventricular fibrosis partly explaining the mechanism behind their prognostic significance.

Identification of Brugada syndrome based on P-wave features: an artificial intelligence-based approach.

AIMS: Brugada syndrome (BrS) is an inherited disease associated with an increased risk of ventricular arrhythmias. Recent studies have reported the presence of an altered atrial phenotype characterized by abnormal P-wave parameters. The aim of this study was to identify BrS based exclusively on P-wave features through an artificial intelligence (AI)-based model. METHODS AND RESULTS: Continuous 5 min 12-lead ECG recordings were obtained in sinus rhythm from (i) patients with spontaneous or ajmaline-induced BrS and no history of AF and (ii) subjects with suspected BrS and negative ajmaline challenge. The recorded ECG signals were processed and divided into epochs of 15 s each. Within these epochs, P-waves were first identified and then averaged. From the averaged P-waves, a total of 67 different features considered relevant to the classification task were extracted. These features were then used to train nine different AI-based supervised classifiers. A total of 2228 averaged P-wave observations, resulting from the analysis of 33 420 P-waves, were obtained from 123 patients (79 BrS+ and 44 BrS-). Averaged P-waves were divided using a patient-wise split, allocating 80% for training and 20% for testing, ensuring data integrity and reducing biases in AI-based model training. The BrS+ patients presented with longer P-wave duration (136 ms vs. 124 ms, P < 0.001) and higher terminal force in lead V1 (2.5 au vs. 1.7 au, P < 0.01) compared with BrS- subjects. Among classifiers, AdaBoost model had the highest values of performance for all the considered metrics, reaching an accuracy of over 81% (sensitivity 86%, specificity 73%). CONCLUSION: An AI machine-learning model is able to identify patients with BrS based only on P-wave characteristics. These findings confirm the presence of an atrial hallmark and open new horizons for AI-guided BrS diagnosis.