P-wave morphology: underlying mechanisms and clinical implications

Clinical and electrocardiographic characteristics of immune checkpoint inhibitor-related myocarditis

BACKGROUND

Immune checkpoint inhibitor (ICI) has become a major breakthrough in the field of tumor therapy, leading to improved survival. This study evaluated the clinical and electrocardiographic characteristics of patients with ICI-related myocarditis.

METHODS

Patients with ICI-related myocarditis were enrolled from 4 centers in China until September 2023. Demographic data (age, sex, comorbidity), types of ICI, clinical manifestations, electrocardiogram (ECG) and treatment were analyzed retrospectively. Arrhythmia and characteristics of ECG were compared according to prognosis and grading.

RESULTS

A total of 29 participants (13 females with a median age of 63.25 years) with ICI-related myocarditis were enrolled. Lung cancer was the most, with a proportion of 31.03 % (9/29). The median time from the first administration of ICI to the diagnosis of myocarditis was 50 days. Camrelizumab was the main type of ICI (9/29). Most patients had non-specific symptoms, dyspnea (n = 16) and palpitation (n = 9) were common. The overall mortality rate was 37.93 % (11/29) with a median follow-up of 9(4,11) days. Compared with the survivors, P-wave abnormality was more common in participants who were dead (24.14 %vs6.90 %, p = 0.010). A total of 19 patients with severe ICI-related myocarditis were included in this study. The proportions of sinus tachycardia (34.48 %vs0.00 %, p = 0.005), premature ventricular complex (27.59 %vs0.00 %, p = 0.027) and atrioventricular block (34.48 %vs3.45 %, p = 0.044) were higher in severe ICI-related myocarditis.

CONCLUSIONS

Clinical manifestations of ICI-related myocarditis usually lacked specificity. ECGs can be manifested as new-onset arrhythmias, ST-T segment changes, fragmented QRS complex, abnormal P wave, prolonged QTc interval and multi‑lead low voltage.

Behavioral and electrophysiological study in Colossoma macropomum treated with different concentrations of Nepeta cataria oil in an immersion bath revealed a therapeutic window for anesthesia

The purpose of this study was to characterize the activity of essential oils from Nepeta Cataria (EON) at concentrations of 125 μ L  L-1, 150 μ L  L-1, 175 μ L  L-1, and 200 μ L  L-1 on the behavior of loss of the posture reflex and recovery of the posture reflex and electrocardiographic activity and recording of the opercular beat of Colossoma macropomum during immersion bathing for a period of 5 min, in order to obtain a window for safe use during anesthesia. The fish (23.38 ± 3.5 g) were assigned to the following experiments: experiment 1 (latency to loss and recovery of the posture reflex): (a) 125 μ L  L-1, (b) 150 μ L  L-1, (c) 175 μ L  L-1, and (d) 200 μ L  L-1 (n = 9) per group. Experiment 2 (electrocardiographic and heartbeat recordings): (a) control group; (b) vehicle control group (2 ml of alcohol per liter of water), (c) 125 μ L  L-1, (d) 150 μ L  L-1, (e) 175 μ L  L-1, and (f) 200 μ L  L-1 (n = 9), per group. All the concentrations used showed efficacy in inducing loss of the posture reflex and reversibility with recovery of the posture reflex, but the electrocardiographic recordings indicated morphographic changes such as bradycardia during induction and p wave apiculation during recovery at the highest concentrations tested. In this way, we suggest a safe use window for short-term anesthesia with EON in the concentration range of 125 to 150 μ L  L-1 for juvenile Colossoma macropomum.

Artificial Intelligence-Enabled Electrocardiography Predicts Future Pacemaker Implantation and Adverse Cardiovascular Events

Medical advances prolonging life have led to more permanent pacemaker implants. When pacemaker implantation (PMI) is commonly caused by sick sinus syndrome or conduction disorders, predicting PMI is challenging, as patients often experience related symptoms. This study was designed to create a deep learning model (DLM) for predicting future PMI from ECG data and assess its ability to predict future cardiovascular events. In this study, a DLM was trained on a dataset of 158,471 ECGs from 42,903 academic medical center patients, with additional validation involving 25,640 medical center patients and 26,538 community hospital patients. Primary analysis focused on predicting PMI within 90 days, while all-cause mortality, cardiovascular disease (CVD) mortality, and the development of various cardiovascular conditions were addressed with secondary analysis. The study's raw ECG DLM achieved area under the curve (AUC) values of 0.870, 0.878, and 0.883 for PMI prediction within 30, 60, and 90 days, respectively, along with sensitivities exceeding 82.0% and specificities over 81.9% in the internal validation. Significant ECG features included the PR interval, corrected QT interval, heart rate, QRS duration, P-wave axis, T-wave axis, and QRS complex axis. The AI-predicted PMI group had higher risks of PMI after 90 days (hazard ratio [HR]: 7.49, 95% CI: 5.40-10.39), all-cause mortality (HR: 1.91, 95% CI: 1.74-2.10), CVD mortality (HR: 3.53, 95% CI: 2.73-4.57), and new-onset adverse cardiovascular events. External validation confirmed the model's accuracy. Through ECG analyses, our AI DLM can alert clinicians and patients to the possibility of future PMI and related mortality and cardiovascular risks, aiding in timely patient intervention.

Interactive teaching of medical 3D cardiac anatomy: atrial anatomy enhanced by ECG and 3D visualization

The most commonly applied way of teaching students to convey the foundations of human anatomy and physiology involves textbooks and lectures. This way of transmitting knowledge causes difficulties for students, especially in the context of three-dimensional imaging of organ structures, and as a consequence translates into difficulties with imagining them. Even despite the rapid uptake of knowledge dissemination provided by online materials, including courses and webinars, there is a clear need for learning programs featuring first-hand immersive experiences tailored to suit individual study paces. In this paper, we present an approach to enhance a classical study program by combining multi-modality data and representing them in a Mixed Reality (MR)-based environment. The advantages of the proposed approach have been proven by the conducted investigation of the relationship between atrial anatomy, its electrophysiological characteristics, and resulting P wave morphology on the electrocardiogram (ECG). Another part of the paper focuses on the role of the sinoatrial node in ECG formation, while the MR-based visualization of combined micro-computed tomography (micro-CT) data with non-invasive CineECG imaging demonstrates the educational application of these advanced technologies for teaching cardiac anatomy and ECG correlations.

Morphology of human sinoatrial node and its surrounding right atrial muscle in the global obesity pandemic-does fat matter?

Introduction

The sinus node (SN) is the main pacemaker site of the heart, located in the upper right atrium at the junction of the superior vena cava and right atrium. The precise morphology of the SN in the human heart remains relatively unclear especially the SN microscopical anatomy in the hearts of aged and obese individuals. In this study, the histology of the SN with surrounding right atrial (RA) muscle was analyzed from young non-obese, aged non-obese, aged obese and young obese individuals. The impacts of aging and obesity on fibrosis, apoptosis and cellular hypertrophy were investigated in the SN and RA. Moreover, the impact of obesity on P wave morphology in ECG was also analyzed to determine the speed and conduction of the impulse generated by the SN.

Methods

Human SN/RA specimens were dissected from 23 post-mortem hearts (preserved in 4% formaldehyde solution), under Polish local ethical rules. The SN/RA tissue blocks were embedded in paraffin and histologically stained with Masson's Trichrome. High and low-magnification images were taken, and analysis was done for appropriate statistical tests on Prism (GraphPad, USA). 12-lead ECGs from 14 patients under Polish local ethical rules were obtained. The P wave morphologies from lead II, lead III and lead aVF were analyzed.

Results

Compared to the surrounding RA, the SN in all four groups has significantly more connective tissue (P ≤ 0.05) (young non-obese individuals, aged non-obese individuals, aged obese individuals and young obese individuals) and significantly smaller nodal cells (P ≤ 0.05) (young non-obese individuals, aged non-obese individuals, aged obese individuals, young obese individuals). In aging, overall, there was a significant increase in fibrosis, apoptosis, and cellular hypertrophy in the SN (P ≤ 0.05) and RA (P ≤ 0.05). Obesity did not further exacerbate fibrosis but caused a further increase in cellular hypertrophy (SN P ≤ 0.05, RA P ≤ 0.05), especially in young obese individuals. However, there was more infiltrating fat within the SN and RA bundles in obesity. Compared to the young non-obese individuals, the young obese individuals showed decreased P wave amplitude and P wave slope in aVF lead.

Discussion

Aging and obesity are two risk factors for extensive fibrosis and cellular hypertrophy in SN and RA. Obesity exacerbates the morphological alterations, especially hypertrophy of nodal and atrial myocytes. These morphological alterations might lead to functional alterations and eventually cause cardiovascular diseases, such as SN dysfunction, atrial fibrillation, bradycardia, and heart failure.

Notched P-wave on digital electrocardiogram predicts the recurrence of atrial fibrillation in patients who have undergone catheter ablation

Background

A notched P-wave is associated with the occurrence of atrial fibrillation (AF). However, the association between a notched P-wave and AF recurrence in patients who have undergone a catheter ablation for AF is unclear.

Methods

We enrolled 100 subjects who underwent catheter ablation for AF (paroxysmal AF: 60 cases; persistent AF: 40 cases). Twelve-lead electrocardiography (ECG) was conducted, and the peak-to-peak distance in the M shape was calculated automatically using a 12-lead ECG analysis system. A notched P-wave was defined as a P-wave with an M-shape and a peak-to-peak distance of ≥20 ms in lead II. We compared the recurrence of AF in the patients with notched P-wave and the others.

Results

The mean follow-up period was 12 ± 8 months, and a recurrence of AF was observed in 28 patients. The recurrence of AF in the notched P-wave group was significantly higher than that in the controls (log rank 5.14, p = .023). A notched P-wave was a significant predictor of the recurrence of AF after adjustment for age, gender, history of heart failure, history of catheter ablation, persistent AF, use of antiarrhythmic drugs, and the left atrial volume index (hazard ratio 2.470, 95% confidence interval 1.065-5.728, p = .035).

Conclusions

Automatically identified notched P-waves with peak-to-peak distance ≥20 ms were associated with AF recurrence in patients who had undergone catheter ablation.

The Role of Galectin-3 Levels for Predicting Paroxysmal Atrial Fibrillation in Patients with Embolic Stroke of Undetermined Source

Background/Objectives: Paroxysmal atrial fibrillation (PAF) is an important cause that is thought main potential factor in Embolic stroke of undetermined source (ESUS). Extended Holter ECG is an expensive and time-consuming examination. It needs another tools for predicting PAF in ESUS patients. In this study, serum galectin-3 levels, ECG parameters (PR interval, P wave time and P wave peak time) LA volume index, LA global peak strain and atrial electromechanical conduction time values were investigated for predicting PAF. Methods: 150 patients with ESUS and 30 volunteers for the control group were recruited to study. 48-72 h Holter ECG monitoring was used for detecting PAF. Patients were divided into two groups (ESUS + PAF and ESUS-PAF) according to the development of PAF in Holter ECG monitoring. Results: 30 patients with ESUS whose Holter ECG monitoring showed PAF, were recruited to the ESUS + PAF group. Other 120 patients with ESUS were recruited to the ESUS-PAF group. PA lateral, PA septum, and PA tricuspid were higher in the ESUS + PAF group (p < 0.001 for all). Serum galectin-3 levels were significantly higher in ESUS + PAF than in ESUS-PAF and control groups (479.0 pg/mL ± 435.8 pg/mL, 297.8 pg/mL ± 280.3 pg/mL, and 125.4 ± 87.0 pg/mL, p < 0.001, respectively). Serum galectin-3 levels were significantly correlated with LAVI, PA lateral, and global peak LA strain (r = 0.246, p = 0.001, p = 0.158, p = 0.035, r = -0.176, p = 0.018, respectively). Conclusion: Serum galectin-3 levels is found higher in ESUS patients which developed PAF and Serum galectin-3 levels are associated LA adverse remodeling in patients with ESUS.

Pulmonary Hypertension Detection Non-Invasively at Point-of-Care Using a Machine-Learned Algorithm

Artificial intelligence, particularly machine learning, has gained prominence in medical research due to its potential to develop non-invasive diagnostics. Pulmonary hypertension presents a diagnostic challenge due to its heterogeneous nature and similarity in symptoms to other cardiovascular conditions. Here, we describe the development of a supervised machine learning model using non-invasive signals (orthogonal voltage gradient and photoplethysmographic) and a hand-crafted library of 3298 features. The developed model achieved a sensitivity of 87% and a specificity of 83%, with an overall Area Under the Receiver Operator Characteristic Curve (AUC-ROC) of 0.93. Subgroup analysis showed consistent performance across genders, age groups and classes of PH. Feature importance analysis revealed changes in metrics that measure conduction, repolarization and respiration as significant contributors to the model. The model demonstrates promising performance in identifying pulmonary hypertension, offering potential for early detection and intervention when embedded in a point-of-care diagnostic system.

Comparing Artificial Intelligence-Enabled Electrocardiogram Models in Identifying Left Atrium Enlargement and Long-term Cardiovascular Risk

BACKGROUND

The role of P-wave in identifying left atrial enlargement (LAE) with the use of artificial intelligence (AI)-enabled electrocardiography (ECG) models is unclear. It is also unknown if AI-enabled single-lead ECG could be used as a diagnostic tool for LAE surveillance. We aimed to build AI-enabled P-wave and single-lead ECG models to identify LAE using sinus rhythm (SR) and non-SR ECGs, and compare the prognostic ability of severe LAE, defined as left atrial diameter ≥ 50 mm, assessed by AI-enabled ECG models vs echocardiography.

METHODS

This retrospective study used data from 382,594 consecutive adults with paired 12-lead ECG and echocardiography performed within 2 weeks of each other at Chang Gung Memorial Hospital. UNet++ was used for P-wave segmentation. ResNet-18 was used to develop deep convolutional neural network-enabled ECG models for discriminating LAE. External validation was performed with the use of data from 11,753 patients from another hospital.

RESULTS

The AI-enabled 12-lead ECG model outperformed other ECG models for classifying LAE, but the single-lead ECG models also showed excellent performance at a left atrial diameter cutoff of 50 mm. AI-enabled ECG models had excellent and fair discrimination on LAE using the SR and the non-SR data set, respectively. Severe LAE identified by AI-enabled ECG models was more predictive of future cardiovascular disease than echocardiography; however, the cumulative incidence of new-onset atrial fibrillation and heart failure was higher in patients with echocardiography-severe LAE than with AI-enabled ECG-severe LAE.

CONCLUSIONS

P-Wave plays a crucial role in discriminating LAE in AI-enabled ECG models. AI-enabled ECG models outperform echocardiography in predicting new-onset cardiovascular diseases associated with severe LAE.

Development of a Non-Invasive Machine-Learned Point-of-Care Rule-Out Test for Coronary Artery Disease

The current standard of care for coronary artery disease (CAD) requires an intake of radioactive or contrast enhancement dyes, radiation exposure, and stress and may take days to weeks for referral to gold-standard cardiac catheterization. The CAD diagnostic pathway would greatly benefit from a test to assess for CAD that enables the physician to rule it out at the point of care, thereby enabling the exploration of other diagnoses more rapidly. We sought to develop a test using machine learning to assess for CAD with a rule-out profile, using an easy-to-acquire signal (without stress/radiation) at the point of care. Given the historic disparate outcomes between sexes and urban/rural geographies in cardiology, we targeted equal performance across sexes in a geographically accessible test. Noninvasive photoplethysmogram and orthogonal voltage gradient signals were simultaneously acquired in a representative clinical population of subjects before invasive catheterization for those with CAD (gold-standard for the confirmation of CAD) and coronary computed tomographic angiography for those without CAD (excellent negative predictive value). Features were measured from the signal and used in machine learning to predict CAD status. The machine-learned algorithm achieved a sensitivity of 90% and specificity of 59%. The rule-out profile was maintained across both sexes, as well as all other relevant subgroups. A test to assess for CAD using machine learning on a noninvasive signal has been successfully developed, showing high performance and rule-out ability. Confirmation of the performance on a large clinical, blinded, enrollment-gated dataset is required before implementation of the test in clinical practice.

Case report: Widely split P' waves in a patient with focal atrial tachycardia

Background

Widely split P waves in sinus rhythm have been reported previously. However, widely split P' waves in focal atrial tachycardia (AT) on a surface electrocardiogram (ECG) have rarely been reported. The electrophysiological mechanism is relatively difficult to clarify, requiring a electrophysiological study.

Case summary

A 67-year-old patient, who had undergone two radiofrequency ablations for atrial fibrillation, presented with recurrent palpitation. During the palpitation episode, the 12-lead ECG showed AT with a 3:1 atrioventricular conduction rate. P' waves were markedly prolonged in duration and widely split in morphology. An electrophysiological study showed that the tachycardia arose from the left atrial appendage (LAA) and was conducted through two distinct pathways. The impulse of one pathway was transmitted solely via the superior part of the atrium, including the Bachmann bundle. The second pathway was conducted via the coronary sinus and transmitted the impulse from the LAA to the ventricle. After the site showed that the earliest activation was ablated, repeated intravenous infusion of isoprenaline and programmed atrial stimulation did not induce tachycardia.

Conclusion

Widely split P' waves in AT indicate intra- and interatrial conduction blocks, which can be easily overlooked due to the presence of low-voltage areas. Therefore, an electrophysiological study is crucial for identifying the origin of the tachycardia and elucidating the mechanistic details.

The electrocardiographic manifestations of pectus excavatum before and after surgical correction

BACKGROUND

Pectus excavatum (PEx) can cause cardiopulmonary limitations due to cardiac compression and displacement. There is limited data on electrocardiogram (ECG) alterations before and after PEx surgical repair, and ECG findings suggesting cardiopulmonary limitations have not been reported. The aim of this study is to explore ECG manifestations of PEx before and after surgery including associations with exercise capacity.

METHODS

A retrospective review of PEx patients who underwent primary repair was performed. ECGs before and after surgical correction were evaluated and the associations between preoperative ECG abnormalities and cardiopulmonary function were investigated.

RESULTS

In total, 310 patients were included (mean age 35.1 ± 11.6 years). Preoperative ECG findings included a predominant negative P wave morphology in V1, and this abnormal pattern significantly decreased from 86.9% to 57.4% (p < 0.001) postoperatively. The presence of abnormal P wave amplitude in lead II (>2.5 mm) significantly decreased from 7.1% to 1.6% postoperatively (p < 0.001). Right bundle branch block (RBBB) (9.4% versus 3.9%, p < 0.001), rsr' patterns (40.6% versus 12.9%, p < 0.001), and T wave inversion in leads V1-V3 (62.3% vs 37.7%, p < 0.001) were observed less frequently after surgery. Preoperative presence of RBBB (OR = 4.8; 95%CI 1.1-21.6) and T wave inversion in leads V1-3 (OR = 2.3; 95%CI 1.3-4.2) were associated with abnormal results in cardiopulmonary exercise testings.

CONCLUSION

Electrocardiographic abnormalities in PEx are frequent and can revert to normal following surgery. Preoperative RBBB and T wave inversion in leads V1-3 suggested a reduction in exercise capacity, serving as a marker for the need for further cardiovascular evaluation of these patients.

Assessment of the efficacy of the electrocardiographic P-wave peak time in predicting atrial high rate episode in patients with cardiac implantable electronic devices

INTRODUCTION & OBJECTIVE

The incidence of atrial high-rate episode (AHRE) is high among patients with cardiac implantable electronic devices (CIEDs). In this context, the objective of this study is to evaluate the efficacies of P-wave indices (PWIs) obtained from the surface electrocardiography (ECG) in predicting future AHRE development.

MATERIAL & METHOD

The study sample consisted of 158 patients with CIEDs. The study group was divided into two subgroups according to the presence of AHRE during device interrogation. PWIs were calculated using the surface ECG.

RESULTS

There was no significant difference between the groups in the P-wave indices (PWIs), i.e., minimum P-wave duration (PWDmin), maximum P-wave duration (PWDmax) and P-wave dispersion (PWDIS). On the other hand, P-wave peak time in V1 lead (PWTV1) and P-wave peak time in D2 lead (PWPTD2) were significantly higher in the AHRE group than in the non-AHRE group.

CONCLUSION

The study findings revealed that novel ECG parameters PWPTV1 and PWPTD2 had high prognostic value in predicting patients likely to develop AHRE.

Assessment of P Wave Indices in Healthy Standardbred Horses

P wave indices are used as non-invasive electrocardiographic markers of atrial remodelling in humans. Few studies have investigated their use in animals. The aim of this study was to measure P wave duration and P wave dispersion (Pd) in healthy standardbred horses and investigate variables that might influence these measurements. A 12-lead electrocardiogram was recorded at rest and P wave indices were calculated in 53 horses. A general linear model was used to investigate the main effects: age, bodyweight, sex, resting heart rate, presence of a murmur, exercise status and the number of years raced. There were significant associations with exercise status for both the maximum P wave duration and Pd, with both values being increased in strenuously exercising versus non-active horses. Furthermore, a significant moderate positive correlation was identified between the duration of exercise (number of years raced) and both Pmax and Pd. No other significant associations were identified. These findings are similar to those reported in elite human athletes versus sedentary individuals. The increases in these P wave indices most likely occur due to prolongation and heterogeneity in atrial conduction time, which are associated with structural and electrical remodelling, and may explain the increased risk of atrial fibrillation in athletic horses.

Electrocardiographic P terminal force in lead V1, its components, and the association with stroke and atrial fibrillation or flutter

BACKGROUND

The electrocardiographic (ECG) marker P terminal force V1 (PTFV1) is generally perceived as a marker of left atrial pathology and has been associated with atrial fibrillation or flutter (AF).

OBJECTIVE

The purpose of this study was to determine the association between PTFV1 components (duration and amplitude) and incident AF and stroke/transient ischemic attack (TIA).

METHODS

The study included patients with an ECG recorded at the Copenhagen General Practitioners Laboratory in 2001 to 2011. PTFV1 ≥4 mV·ms was considered abnormal. Patients with abnormal PTFV1 were stratified into tertiles based on duration (PTDV1) and amplitude (PTAV1) values. Cox regressions adjusted for age, sex, and relevant comorbidities were used to investigate associations between abnormal PTFV1 components and AF and stroke/TIA.

RESULTS

Of 267,636 patients, 5803 had AF and 18,176 had stroke/TIA (follow-up 6.5 years). Abnormal PTFV1 was present in 44,549 subjects (16.7%) and was associated with an increased risk of AF and stroke/TIA. Among patients with abnormal PTFV1, the highest tertile of PTDV1 (78-97 ms) was associated with the highest risk of AF (hazard ratio [HR] 1.37; 95% confidence interval [CI] 1.23-1.52) and highest risk of stroke/TIA (HR 1.13; 95% CI 1.05 -1.20). For PTAV1, the highest tertile (78-126 μV) conferred the highest risk of AF and stroke/TIA (HR 1.20; 95% CI 1.09-1.32; and HR 1.21; 95% CI 1.14-1.25, respectively).

CONCLUSION

Abnormal PTFV1 was associated with an increased risk of AF and stroke/TIA. Increasing PTDV1 showed a dose-response relationship with the development of AF and stroke/TIA, whereas the association between PTAV1 and AF was less apparent.

Toward ECG-based analysis of hypertrophic cardiomyopathy: a novel ECG segmentation method for handling abnormalities

OBJECTIVE

Abnormalities in impulse propagation and cardiac repolarization are frequent in hypertrophic cardiomyopathy (HCM), leading to abnormalities in 12-lead electrocardiograms (ECGs). Computational ECG analysis can identify electrophysiological and structural remodeling and predict arrhythmias. This requires accurate ECG segmentation. It is unknown whether current segmentation methods developed using datasets containing annotations for mostly normal heartbeats perform well in HCM. Here, we present a segmentation method to effectively identify ECG waves across 12-lead HCM ECGs.

METHODS

We develop (1) a web-based tool that permits manual annotations of P, P', QRS, R', S', T, T', U, J, epsilon waves, QRS complex slurring, and atrial fibrillation by 3 experts and (2) an easy-to-implement segmentation method that effectively identifies ECG waves in normal and abnormal heartbeats. Our method was tested on 131 12-lead HCM ECGs and 2 public ECG sets to evaluate its performance in non-HCM ECGs.

RESULTS

Over the HCM dataset, our method obtained a sensitivity of 99.2% and 98.1% and a positive predictive value of 92% and 95.3% when detecting QRS complex and T-offset, respectively, significantly outperforming a state-of-the-art segmentation method previously employed for HCM analysis. Over public ECG sets, it significantly outperformed 3 state-of-the-art methods when detecting P-onset and peak, T-offset, and QRS-onset and peak regarding the positive predictive value and segmentation error. It performed at a level similar to other methods in other tasks.

CONCLUSION

Our method accurately identified ECG waves in the HCM dataset, outperforming a state-of-the-art method, and demonstrated similar good performance as other methods in normal/non-HCM ECG sets.

P Wave Parameters and Indices: A Critical Appraisal of Clinical Utility, Challenges, and Future Research-A Consensus Document Endorsed by the International Society of Electrocardiology and the International Society for Holter and Noninvasive Electrocardiology

Atrial cardiomyopathy, characterized by abnormalities in atrial structure and function, is associated with increased risk of adverse cardiovascular and neurocognitive outcomes, independent of atrial fibrillation. There exists a critical unmet need for a clinical tool that is cost-effective, easy to use, and that can diagnose atrial cardiomyopathy. P wave parameters (PWPs) reflect underlying atrial structure, size, and electrical activation; alterations in these factors manifest as abnormalities in PWPs that can be readily ascertained from a standard 12-lead ECG and potentially be used to aid clinical decision-making. PWPs include P wave duration, interatrial block, P wave terminal force in V₁, P wave axis, P wave voltage, P wave area, and P wave dispersion. PWPs can be combined to yield an index (P wave index), such as the morphology-voltage-P-wave duration ECG risk score. Abnormal PWPs have been shown in population-based cohort studies to be independently associated with higher risks of atrial fibrillation, ischemic stroke, sudden cardiac death, and dementia. Additionally, PWPs, either individually or in combination (as a P wave index), have been reported to enhance prediction of atrial fibrillation or ischemic stroke. To facilitate translation of PWPs to routine clinical practice, additional work is needed to standardize measurement of PWPs (eg, via semiautomated or automated measurement), confirm their reliability and predictive value, leverage novel approaches (eg, wavelet analysis of P waves and machine learning algorithms), and finally, define the risk-benefit ratio of specific interventions in high-risk individuals. Our ultimate goal is to repurpose the ubiquitous 12-lead ECG to advance the study, diagnosis, and treatment of atrial cardiomyopathy, thus overcoming critical challenges in prevention of cardiovascular disease and dementia.

Extended ECG Improves Classification of Paroxysmal and Persistent Atrial Fibrillation Based on P- and f-Waves

Background

The standard 12-lead ECG has been shown to be of value in characterizing atrial conduction properties. The added value of extended ECG recordings (longer recordings from more sites) has not been systematically explored yet.

Objective

The aim of this study is to employ an extended ECG to identify characteristics of atrial electrical activity related to paroxysmal vs. persistent atrial fibrillation (AF).

Methods

In 247 participants scheduled for AF ablation, an extended ECG was recorded (12 standard plus 3 additional leads, 5 min recording, no filtering). For patients presenting in sinus rhythm (SR), the signal-averaged P-wave and the spatiotemporal P-wave variability was analyzed. For patients presenting in AF, f-wave properties in the QRST (the amplitude complex of the ventricular electrical activity: Q-, R-, S-, and T-wave)-canceled ECG were determined.

Results

Significant differences between paroxysmal (N = 152) and persistent patients with AF (N = 95) were found in several P-wave and f-wave parameters, including parameters that can only be calculated from an extended ECG. Furthermore, a moderate, but significant correlation was found between echocardiographic parameters and P-wave and f-wave parameters. There was a moderate correlation of left atrial (LA) diameter with P-wave energy duration (r = 0.317, p < 0.001) and f-wave amplitude in lead A3 (r = -0.389, p = 0.002). The AF-type classification performance significantly improved when parameters calculated from the extended ECG were taken into account [area under the curve (AUC) = 0.58, interquartile range (IQR) 0.50-0.64 for standard ECG parameters only vs. AUC = 0.76, IQR 0.70-0.80 for extended ECG parameters, p < 0.001].

Conclusion

The P- and f-wave analysis of extended ECG configurations identified specific ECG features allowing improved classification of paroxysmal vs. persistent AF. The extended ECG significantly improved AF-type classification in our analyzed data as compared to a standard 10-s 12-lead ECG. Whether this can result in a better clinical AF type classification warrants further prospective study.

An Exploratory Study on Vectorcardiographic Identification of the Site of Origin of Focally Induced Premature Depolarizations in Horses, Part I: The Atria

In human cardiology, the anatomical origin of atrial premature depolarizations (APDs) is derived from P wave characteristics on a 12-lead electrocardiogram (ECG) and from vectorcardiography (VCG). The objective of this study is to differentiate between anatomical locations of APDs and to differentiate APDs from sinus rhythm (SR) based upon VCG characteristics in seven horses without cardiovascular disease. A 12-lead ECG was recorded under general anaesthesia while endomyocardial atrial pacing was performed (800−1000 ms cycle length) at the left atrial free wall and septum, right atrial free wall, intervenous tubercle, as well as at the junction with the cranial and caudal vena cava. Catheter positioning was guided by 3D electro-anatomical mapping and transthoracic ultrasound. The VCG was calculated from the 12-lead ECG using custom-made algorithms and was used to determine the mean electrical axis of the first and second half of the P wave. An ANOVA for spherical data was used to test if the maximal directions between each paced location and the maximal directions between every paced location and SR were significantly (p < 0.05) different. Atrial pacing data were not available from the LA septum in three horses, the intervenous tubercle in two horses, and from the LA free wall in one horse. The directions of the maximal electrical axes showed significant differences between all paced locations and between the paced locations and SR. The current results suggest that VCG is useful for identifying the anatomical origin of an atrial ectopy.

Investigating the association between P wave duration and atrial fibrillation recurrence after radiofrequency ablation in early persistent atrial fibrillation patients

BACKGROUND

In the present study, we aimed to explore the association between P wave duration, as the measured time from the start point of the P wave to the end point, and atrial fibrillation recurrence after transcatheter radiofrequency ablation in patients with early persistent atrial fibrillation.

METHODS

Patients with early persistent atrial fibrillation who underwent the first radiofrequency ablation procedure were retrospectively analyzed. The electrocardiographic, echocardiographic and clinical data of the enrolled patients before and after operation were collected and recorded. After adjusting confounding factors and performing stratified analysis, the association between the P wave duration and the atrial fibrillation recurrence of patients with early persistent atrial fibrillation after radiofrequency ablation was explored.

RESULTS

The proportions of atrial fibrillation recurrence of the low, medium, and high P wave duration groups were 6.4%, 19.7%, and 47.0%, respectively. After potential confounding factors were adjusted, the risk of atrial fibrillation recurrence gradually increased with the increase of P wave duration (odds ratio: 1.093, 95% confidence interval: 1.063-1.124, p < 0.001). This trend was statistically significant (odds ratio: 1.099, 95% confidence interval: 1.052-1.149, p < 0.001), especially in comparison of high vs. low (odds ratio: 16.99, 95% confidence interval: 4.75-60.78, p < 0.001). Curve fitting showed that there was a linear and positive association between the P wave duration and the risk of atrial fibrillation recurrence. This association was consistent in different subgroups based on gender, drinking, history of smoking, hypertension, diabetes mellitus, peripheral artery disease, stroke or transient ischemia attack, hyperlipidemia, heart failure, and heart rate, suggesting that there was no significant interaction between different grouping parameters and the association (p for interaction range = 0.217-0.965).

CONCLUSIONS

In patients with early persistent atrial fibrillation who underwent radiofrequency ablation procedure for the first time and converted to sinus rhythm, the P wave duration within 72 h after the procedure was independently associated with the risk of atrial fibrillation recurrence, and such association was linear and positive.

Markers of susceptibility to cardiac arrhythmia in experimental spinal cord injury and the impact of sympathetic stimulation and exercise training

Injury to descending autonomic (sympathetic) pathways is common after high-level spinal cord injury (SCI) and associated with abnormal blood pressure and heart rate regulation. In individuals with high-level SCI, abnormal sympathovagal balance (such as during autonomic dysreflexia; paroxysmal hypertension provoked by sensory stimuli below the injury) is proarrhythmogenic. Exercise training is a key component of SCI rehabilitation and management of cardiovascular disease risk, but it is unclear whether exercise training influences susceptibility to cardiac arrhythmia. We aimed to evaluate: (i) whether susceptibility to arrhythmia increases in a rodent-model of SCI; (ii) the impact of the sympathomimetic drug dobutamine (DOB) on arrhythmia risk; (iii) whether exercise training ameliorates arrhythmia risk. Twenty-one Wistar rats were divided into 3 subgroups: T2-contusive SCI (T2, n = 7), T2-contusive SCI completing passive hindlimb cycling training (PHLC, n = 7), and T10-contusive SCI (T10, n = 7). Known electrocardiographic arrhythmia markers and heart rate variability parameters were evaluated before (PRE), 1-week (POST) and 5-weeks post-SCI (TERM) at baseline and during DOB infusion (30 μg/kg/min). Baseline markers of arrhythmia risk were increased in both T2 and T10 animals. DOB decreased R-R interval (p < 0.001), and increased markers of risk for ventricular arrhythmia, particularly in high-level (T2) animals (p < 0.05). Exercise training blunted the exacerbation of markers of arrhythmia risk in the presence of DOB. Markers of risk for cardiac arrhythmia are increased in experimental SCI, and DOB further increases arrhythmia risk in high-level SCI. Exercise training did not improve markers of arrhythmia risk at rest, but did ameliorate markers of arrhythmia risk during sympathetic stimulation.

Evolution of P-wave indices during long-term follow-up as markers of atrial substrate progression in arrhythmogenic right ventricular cardiomyopathy

AIMS

Patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) have increased prevalence of atrial arrhythmias indicating atrial involvement in the disease. We aimed to assess the long-term evolution of P-wave indices as electrocardiographic (ECG) markers of atrial substrate during ARVC progression.

METHODS AND RESULTS

We included 100 patients with a definite ARVC diagnosis according to 2010 Task Force criteria [34% females, median age 41 (inter-quartile range 30-55) years]. All available sinus rhythm ECGs (n = 1504) were extracted from the regional electronic ECG databases and automatically processed using Glasgow algorithm. P-wave duration, P-wave area, P-wave frontal axis, and prevalence of abnormal P terminal force in lead V1 (aPTF-V1) were assessed and compared at ARVC diagnosis, 10 years before and up to 15 years after diagnosis.Prior to ARVC diagnosis, none of the P-wave indices differed significantly from the data at ARVC diagnosis. After ascertainment of ARVC diagnosis, P-wave area in lead V1 decreased from -1 to -30 µV ms at 5 years (P = 0.002). P-wave area in lead V2 decreased from 82 µV ms at ARVC diagnosis to 42 µV ms 10 years after ARVC diagnosis (P = 0.006). The prevalence of aPTF-V1 increased from 5% at ARVC diagnosis to 18% by the 15th year of follow-up (P = 0.004). P-wave duration and frontal axis did not change during disease progression.

CONCLUSION

Initial ARVC progression was associated with P-wave flattening in right precordial leads and in later disease stages an increased prevalence of aPTF-V1 was seen.

Orthogonal P-wave morphology, conventional P-wave indices, and the risk of atrial fibrillation in the general population using data from the Finnish Hospital Discharge Register

AIMS

Identifying subjects at high and low risk of atrial fibrillation (AF) is of interest. This study aims to assess the risk of AF associated with electrocardiographic (ECG) markers linked to atrial fibrosis: P-wave prolongation, 3rd-degree interatrial block, P-terminal force in lead V1, and orthogonal P-wave morphology.

METHODS AND RESULTS

P-wave parameters were assessed in a representative Finnish population sample aged ≥30 years (n = 7217, 46.0% male, mean age 51.4 years). Subjects (n = 5489) with a readable ECG including the orthogonal leads, sinus rhythm, and a predefined orthogonal P-wave morphology type [positive in leads X and Y and either negative (Type 1) or ± biphasic (Type 2) in lead Z; Type 3 defined as positive in lead X and ± biphasic in lead Y], were followed 10 years from the baseline examinations (performed 1978-80). Subjects discharged with AF diagnosis after any-cause hospitalization (n = 124) were defined as having developed AF. Third-degree interatrial block was defined as P-wave ≥120 ms and the presence of ≥2 ± biphasic P waves in the inferior leads. Hazard ratios (HRs) and confidence intervals (CIs) were assessed with Cox models. Third-degree interatrial block (n = 103, HR 3.18, 95% CI 1.66-6.13; P = 0.001) and Type 3 morphology (n = 216, HR 3.01, 95% CI 1.66-5.45; P < 0.001) were independently associated with the risk of hospitalization with AF. Subjects with P-wave <110 ms and Type 1 morphology (n = 2074) were at low risk (HR 0.46, 95% CI 0.26-0.83; P = 0.006), compared to the rest of the subjects.

CONCLUSION

P-wave parameters associate with the risk of hospitalization with AF.

P-Wave Terminal Force in Dogs With Myxomatous Mitral Valve Disease

P-wave terminal force (PTF) is accepted as an electrocardiographic criteria to assess left atrial abnormalities in humans. In this study, the applicability of PTF in dogs with myxomatous mitral valve disease (MMVD) was evaluated, and compared its ability to identify left atrial dilatation with 4 other P-wave derived parameters. Seventy-four dogs with echocardiographically diagnosed MMVD were recruited for this prospective cross-sectional study. Also, 47 healthy dogs were included to serve as controls. All dogs underwent physical, electrocardiographic and standard echocardiographic examinations prior to enrollment. Electrocardiographic measurements were obtained from simultaneous recordings at three different locations for precordial lead V₁. PTF was defined as the deflection following the second half of the P-wave, and was best documented at the first and third right intercostal spaces. In those locations, the P-wave was negative and P-wave terminal force was recognized as a positive undulation in baseline following P-wave. P-wave terminal force and P-wave duration measured from recordings obtained at either the first or third right intercostal spaces had poor to weak correlations (P < .05) with echocardiographic surrogates of cardiac remodeling and congestion. In dogs with MMVD, only P-wave duration and P-wave area distinguished normal and dilated left atria (P < .05). In conclusion, PTF had positive polarity and was best recorded when precordial lead V₁ electrode was placed at the most cranial right intercostal locations. PTF failed to reliably identify left atrial enlargement in dogs with MMVD.

Stability analysis on the effects of heart rate variability and premature activation of atrial ECG dynamics using ARMAX model

The cellular action potential of cardiac muscles generates Electrocardiogram (ECG) signals. Disturbances in cardiac cells are determined by analyzing the stability of ECG intervals. The PTa Interval (PTaI) of ECG represents the atrial Action Potential Duration (APD) and the evaluation of the causes of PTaI instability can predict the onset of arrhythmia. This study developed an Autoregressive Moving Average with Exogenous Input (ARMAX) model to explore the roles of Heart Rate Variability (HRV) and Premature Activation (PA) in PTaI dynamics using PTaI and PP Interval (PPI) as exogenous inputs. Minute ECG signals were collected from twenty Normal Sinus Rhythm (NSR) and ten Atrial Tachycardia (AT) volunteers. The EDAN PC ECG system was used in the Modified Limb Lead (MLL) configuration to evaluate instability. The instabilities of PTaI were found at the minimum model orders (A_min) of 10 and 11, in the NSR and AT groups, respectively. In the NSR group, the predominant reason for PTaI instability was HRV, whereas among AT patients, it was largely due to PA that preceded the onset of AT. The proposed model showed better prediction of PTaI with minimum Mean Square Error (MSE) between the measured and predicted PTa Intervals (PTaIs). The factor that led to PTaI instability in AT patients was found to be different from that of the NSR group. The frequency of PA (f_PA) was found to contribute more in the AT than the NSR group. The developed ARMAX model was better in predicting instability of atrial ECG dynamics in both groups than other autoregressive models currently in use.

The effect of P wave indices on new onset atrial fibrillation after trans-catheter aortic valve replacement

OBJECTIVES

Data is scarce regarding the relation between P wave indices and new onset atrial fibrillation (NOAF) after trans-catheter aortic valve replacement (TAVR).

AIMS

The present study aimed to find out certain characteristics of P wave that may predict NOAF after TAVR procedure.

METHOD

Patients with severe calcific aortic stenosis who had undergone TAVR procedure between 2013 and 2019 in two centers were investigated. P wave abnormalities that have been resumed to reflect impaired atrial conduction; partial and advanced inter atrial block (IAB), P-wave terminal force in lead V1, P wave dispersion, reduced amplitude of P- wave in lead I, P wave peak time in D2 and V1 were evaluated on pre- procedural 12 derivation surface electrocardiography (ECG). The relationship between these parameters and incidence of NOAF during index hospitalization was evaluated.

RESULTS

A total of 227 consecutive patients (median age 79 [74-83]; 134 [59%] female) were included in the study. NOAF occurred in 46 (20.3%) patients. P wave duration, P wave dispersion, number of patients with partial and advanced IAB, left atrium diameter, STS score were higher in NOAF patients. Use of general anesthesia and history of prior open heart surgery were also more frequent in NOAF group. In multivariable logistic regression analysis; advanced IAB (OR 6.413 [2.555-16.095] p < 0.01), P wave dispersion (OR 3.544 [1.431-8.780] p = 0.006) and use of general anesthesia (OR 2.736 [1.225-6.109] p = 0.014) were independent predictors of NOAF.

CONCLUSION

Among P wave abnormalities evaluated on pre-procedural 12-derivation surface ECG, advanced IAB and P wave dispersion may predict NOAF after TAVR procedure.

In-Hospital Prognostic Value of Electrocardiographic Parameters Other Than ST-Segment Changes in Acute Myocardial Infarction: Literature Review and Future Perspectives

Electrocardiography (ECG) remains an irreplaceable tool in the management of the patients with myocardial infarction, with evaluation of the QRS and ST segment being the present major focus. Several ECG parameters have already been proposed to have prognostic value with regard to both in-hospital and long-term follow-up of patients. In this review, we discuss various ECG parameters other than ST segment changes, particularly with regard to their in-hospital prognostic importance. Our review not only evaluates the prognostic segments and parts of ECG, but also highlights the need for an integrative approach in big data to re-assess the parameters reported to predict in-hospital prognosis. The evolving importance of artificial intelligence in evaluation of ECG, particularly with regard to predicting prognosis, and the potential integration with other patient characteristics to predict prognosis, are discussed.

P-wave axis is associated with all-cause mortality in diabetes: The ACCORD trial

Abnormal P-wave axis (PWA) has emerged as a novel marker of risk for both cardiovascular disease (CVD) and all-cause mortality (ACM) in the general population, though this relationship has not been adequately explored among those with type 2 diabetes (DM2). We aimed to explore the association between abnormal PWA and ACM among a large, well-phenotyped group of participants with DM2 from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. This analysis included 8899 ACCORD participants with available PWA data on baseline electrocardiogram. Cox proportional hazards models were used to examine the association between PWA and ACM in models adjusted for demographics, ACCORD trial treatment assignment, and potential confounders. PWA was modeled as either normal (0° -75°) or abnormal (<0° or >75°). Over 44,000 person-years of follow up, there were 609 deaths. Participants with abnormal PWA had increased risk of ACM (HR 1.61, 95% CI 1.25-2.08). After multivariable adjustment, the association remained significant (HR 1.33, 95% CI 1.03-1.72). This relationship was similar in subgroups stratified by age, race, sex, and history of CVD. Among ACCORD trial participants, abnormal PWA was associated with an increased risk of mortality. Abnormal PWA may have added value beyond traditional risk factors in prediction models.

Electrocardiogram characteristics of P wave associated with successful pulmonary vein isolation in patients with paroxysmal atrial fibrillation: Significance of changes in P-wave duration and notched P wave

Background

The mechanisms involved in changes in P wave following catheter ablation for atrial fibrillation (AF) are uncertain. This study aimed to assess the relationship between changes in P‐wave morphology and pulmonary vein (PV) reconnection following ablation by the assessment of 12‐lead surface electrocardiogram and signal‐averaged electrocardiogram.

Methods

This retrospective study included 115 consecutive patients with paroxysmal AF that underwent repeat ablation for recurrence following initial ablation. We investigated changes in P‐wave morphology between baseline and repeat procedure in patients with and without PV reconnection. The study also included as validation group without recurrence (n = 67) following initial ablation.

Results

The maximum P‐wave duration (PWD) was significantly decreased from baseline to just after the procedure in all groups. However, for the PV reconnection group (n = 100), the maximum PWD was significantly increased again at the repeat procedure. In contrast, the maximum PWD was significantly reduced between baseline and repeat procedure in the non‐PV reconnection group (n = 15). The signal‐averaged PWD was significantly decreased from baseline to repeat procedure in the non‐PV reconnection group, but, conversely, was increased in the PV reconnection group. In the non‐PV reconnection group, the disappearance of notched P wave was detected in 8 of 15 patients (53%), which was significantly higher than in other groups (p = .001). A new or delayed notched P wave was identified in the PV reconnection group only. These results were confirmed in the validation group.

Conclusions

The reverse dynamics of PWD after initial shortening directly following ablation were significantly associated with PV reconnection.

Understanding the Beat-to-Beat Variations of P-Waves Morphologies in AF Patients During Sinus Rhythm: A Scoping Review of the Atrial Simulation Studies

The remarkable advances in high-performance computing and the resulting increase of the computational power have the potential to leverage computational cardiology toward improving our understanding of the pathophysiological mechanisms of arrhythmias, such as Atrial Fibrillation (AF). In AF, a complex interaction between various triggers and the atrial substrate is considered to be the leading cause of AF initiation and perpetuation. In electrocardiography (ECG), P-wave is supposed to reflect atrial depolarization. It has been found that even during sinus rhythm (SR), multiple P-wave morphologies are present in AF patients with a history of AF, suggesting a higher dispersion of the conduction route in this population. In this scoping review, we focused on the mechanisms which modify the electrical substrate of the atria in AF patients, while investigating the existence of computational models that simulate the propagation of the electrical signal through different routes. The adopted review methodology is based on a structured analytical framework which includes the extraction of the keywords based on an initial limited bibliographic search, the extensive literature search and finally the identification of relevant articles based on the reference list of the studies. The leading mechanisms identified were classified according to their scale, spanning from mechanisms in the cell, tissue or organ level, and the produced outputs. The computational modeling approaches for each of the factors that influence the initiation and the perpetuation of AF are presented here to provide a clear overview of the existing literature. Several levels of categorization were adopted while the studies which aim to translate their findings to ECG phenotyping are highlighted. The results denote the availability of multiple models, which are appropriate under specific conditions. However, the consideration of complex scenarios taking into account multiple spatiotemporal scales, personalization of electrophysiological and anatomical models and the reproducibility in terms of ECG phenotyping has only partially been tackled so far.

Coefficient of variation of P-wave duration measured using an automated measurement system predicts recurrence of atrial fibrillation

BACKGROUND

P-wave parameters representing atrial conduction heterogeneity are associated with recurrence of atrial fibrillation (AF) after catheter ablation. However, intra- and inter-observer variabilities are unavoidable during manual measurement of P-wave parameters.

METHODS

The study included 201 patients with paroxysmal AF who underwent catheter ablation. P-wave duration (PWD) was measured using a computerized automated measurement system with a surface 12-lead electrocardiogram. The coefficient of variation of PWD (CV-PWD) across the 12 electrocardiographic leads was determined as an index of atrial conduction heterogeneity.

RESULTS

AF did not recur in 157 (78%) patients during a 12-month follow-up period. CV-PWD assessed before catheter ablation was not different between the AF-recurrent and AF-free groups (0.069 ± 0.023 vs. 0.069 ± 0.023, P = 0.090). However, CV-PWD measured after catheter ablation was significantly larger in the AF-recurrent group than in the AF-free group (0.090 ± 0.037 vs. 0.073 ± 0.024, P < 0.001). In receiver operating curve analysis, CV-PWD assessed after catheter ablation achieved an area under the curve of 0.702; the sensitivity, specificity, and positive and negative predictive values were 68%, 69%, 38%, and 88%, respectively, for the cut-off value of 0.080. During the follow-up period, AF freedom rates of high CV-PWD patients (CV-PWD ≥ 0.080) and low CV-PWD patients (CV-PWD < 0.080) were 65% and 88%, respectively.

CONCLUSIONS

CV-PWD determined using an automated measurement system was associated with AF recurrence after catheter ablation in patients with paroxysmal AF.

Electrocardiographic left atrial abnormalities predict cardiovascular mortality

OBJECTIVE

Clinical utilization of electrocardiography for diagnosis of left atrial abnormalities is hampered by variable P-wave morphologies, multiple empiric criteria, and lack of an imaging "gold standard". Our aim was to determine the prevalence of P-wave patterns and demonstrate which components have associations with cardiovascular death (CVD).

METHODS

This is a retrospective analysis of 20,827 veterans <56 years of age who underwent electrocardiograms at a Veteran's Affairs Medical Center from 1987 to 1999, followed for a median duration of 17.8 years for CVD. Receiver Operating Characteristic, Kaplan-Meier and Cox Hazard analyses were applied, the latter with adjustment for age, gender and electrocardiography abnormalities.

RESULTS

The mean age was 43.3 ± 8 years, and 888 CVD (4.3%) occurred. A single positive deflection of the P-wave (Pattern 1) was present in 29% for V1 and 81% for V2. A singular negative P-wave (Pattern 2) was present in 4.6% for V1 and 1.6% in V2. A P-wave with an upward component followed by downward component (Pattern 3) was present in 64.5% for V1 and 17.5% for V2. When the downward component in Patterns 2 and/or 3 is at least -100 μV, a significant association is observed with CVD (adjusted hazard ratios [HRs] 2.9-4.1, P < 0.001). Total P-wave duration ≥140 ms was also associated with CVD (adjusted HR 2.2, P < 0.001).

CONCLUSIONS

A negative P-wave in V1 or V2 ≤-100 μV, and P-wave with a duration of ≥140 ms, all have independent and significant associations with CVD, with HRs comparable to other electrocardiography abnormalities.

Beat-to-beat P-wave morphology as a predictor of paroxysmal atrial fibrillation

BACKGROUND AND OBJECTIVES

Atrial Fibrillation (AF) is the most common cardiac arrhythmia. The initiation and the perpetuation of AF is linked with phenomena of atrial remodeling, referring to the modification of the electrical and structural characteristics of the atrium. P-wave morphology analysis can reveal information regarding the propagation of the electrical activity on the atrial substrate. The purpose of this study is to investigate patterns on the P-wave morphology that may occur in patients with Paroxysmal AF (PAF) and which can be the basis for distinguishing between PAF and healthy subjects.

METHODS

Vectorcardiographic signals in the three orthogonal axes (X, Y and Z), of 3-5 min duration, were analyzed during SR. In total 29 PAF patients and 34 healthy volunteers were included in the analysis. These data were divided into two distinct datasets, one for the training and one for the testing of the proposed approach. The method is based on the identification of the dominant and the secondary P-wave morphology by combining adaptive k-means clustering of morphologies and a beat-to-beat cross correlation technique. The P-waves of the dominant morphology were further analyzed using wavelet transform whereas time domain characteristics were also extracted. Following a feature selection step, a SVM classifier was trained, for the discrimination of the PAF patients from the healthy subjects, while its accuracy was tested using the independent testing dataset.

RESULTS

In the cohort study, in both groups, the majority of the P-waves matched a main and a secondary morphology, while other morphologies were also present. The percentage of P-waves which simultaneously matched the main morphology in all three leads was lower in PAF patients (90.4 ± 7.8%) than in healthy subjects (95.5 ± 3.4%, p= 0.019). Three optimal scale bands were found and wavelet parameters were extracted which presented statistically significant differences between the two groups. Classification between the two groups was based on a feature selection process which highlighted 7 features, while an SVM classifier resulted a balanced accuracy equal to 93.75%. The results show the virtue of beat-to-beat analysis for PAF prediction.

CONCLUSION

The difference in the percentage of the main P-wave-morphology and in the P-wave time-frequency characteristics suggests a higher electrical instability of the atrial substrate in patients with PAF and different conduction patterns in the atria.

ECG markers associated with ischemic stroke at young age - a case-control study

INTRODUCTION

Certain electrocardiographic (ECG) abnormalities are associated with ischemic stroke (IS), especially cardioembolic subtype. Besides atrial fibrillation, markers of left ventricular hypertrophy (LVH) or atrial pathology also reflect elevated risk. We studied the association of ECG markers with IS in young adults.

METHODS

We performed a case-control study including 567 consecutive IS patients aged 15-49 years (inclusion period: 1994-2007) and one or two age- and sex-matched control subjects enrolled during 1978-1980 (n = 1033), and investigated also the stroke aetiologic subgroups. We studied ECGs of all participants for markers of atrial abnormality, i.e. P-terminal force (PTF) on lead V1, interatrial blocks (IAB; P-wave duration ≥110 ms), and LVH. Conditional logistic regression analyses were used.

RESULTS

IAB (hazard ratio [HR]: 1.57, 95% confidence interval [CI]: 1.16-2.13) and PTF combined with LVH (HR: 6.83, 95% CI: 1.65-28.31), were independently associated with IS. LVH, abnormal P-wave (HR: 6.87, 95% CI: 1.97-135.29), PTF, IAB, and combinations of these P-wave abnormalities with LVH - were associated with cardioembolic subtype. Abnormal P-wave and IAB were associated with cryptogenic stroke subtype. In unadjusted analysis, LVH was associated with small-vessel disease subtype.

CONCLUSION

P-wave abnormalities on ECG were associated with cardioembolic but also with a cryptogenic subtype of IS. Key messages ECG patterns associated with atrial pathology are markers of increased risk of ischemic stroke in young adults. The ECG markers reflecting atrial pathology were seen in patients with cardioembolic and cryptogenic subtypes of ischemic stroke.

Incidence rates, correlates, and prognosis of electrocardiographic P-wave abnormalities - a nationwide population-based study

BACKGROUND

Scant data exist on incidence rates, correlates, and prognosis of electrocardiographic P-wave abnormalities in the general population.

METHODS

We recorded ECG and measured conventional cardiovascular risk factors in 5667 Finns who were followed up for incident atrial fibrillation (AF). We obtained repeat ECGs from 3089 individuals 11years later.

RESULTS

The incidence rates of prolonged P-wave duration, abnormal P terminal force (PTF), left P-wave axis deviation, and right P-wave axis deviation were 16.0%, 7.4%, 3.4%, and 2.2%, respectively. Older age and higher BMI were associated with incident prolonged P-wave duration and abnormal PTF (P≤0.01). Higher blood pressure was associated with incident prolonged P-wave duration and right P-wave axis deviation (P≤0.01). During follow-up, only prolonged P-wave duration predicted AF (multivariable-adjusted hazard ratio, 1.38; P=0.001).

CONCLUSIONS

Modifiable risk factors associate with P-wave abnormalities that are common and may represent intermediate steps of atrial cardiomyopathy on a pathway leading to AF.

Epicardial fat thickness correlates with P-wave duration, left atrial size and decreased left ventricular systolic function in morbid obesity

BACKGROUND AND AIM

Epicardial fat (EF) is increased in obesity and has important interactions with atrial and ventricular myocardium. Most of the evidence in this scenario can be confused by the presence of comorbidities such as hypertension, diabetes and dyslipidemia, which are very common in this population. The influence of EF on atrial remodeling and cardiac function demands further investigation on morbidly obese without these comorbidities.

METHODS AND RESULTS

We prospectively recruited 20 metabolically healthy morbidly obese and 20 normo-weights controls. The maximum P-wave duration (PWD) was analyzed by 12-lead electrocardiogram. Left atrial diameter (LAD), left ventricular ejection fraction (LVEF) and EF thickness (EFT) were evaluated by two-dimensional echocardiography. The mean of maximum PWD and LAD were significantly larger in the obese group as compared to the control group: 109.55 ± 11.52 ms × 89.38 ± 11.19 ms and 36.12 ± 3.46 mm × 31.45 ± 2.64 mm, (p < 0.0001). The mean LVEF was lower in the obese group: 63.15 ± 4.25% × 66.17 ± 3.37% (p < 0.017). The mean EFT was higher in the obese group: 7.72 ± 1.60 mm × 3.10 ± 0.85 mm (p < 0.0001). A positive correlation was found between EFT and PWD (r = 0.70; p = 0.001) and LAD (r = 0.667; p = 0.001). An inverse correlation was found between EFT and LVEF (r = -0.523; p = 0.001). In a multiple multivariate regression analysis the EFT remains correlated with LAD and LVEF.

CONCLUSIONS

In a select group of morbidly obese, the excess of EF had a significant impact on atrial remodeling and cardiac function.

Role of Epicardial Adipose Tissue in Health and Disease: A Matter of Fat?

Epicardial adipose tissue (EAT) is a small but very biologically active ectopic fat depot that surrounds the heart. Given its rapid metabolism, thermogenic capacity, unique transcriptome, secretory profile, and simply measurability, epicardial fat has drawn increasing attention among researchers attempting to elucidate its putative role in health and cardiovascular diseases. The cellular crosstalk between epicardial adipocytes and cells of the vascular wall or myocytes is high and suggests a local role for this tissue. The balance between protective and proinflammatory/profibrotic cytokines, chemokines, and adipokines released by EAT seem to be a key element in atherogenesis and could represent a future therapeutic target. EAT amount has been found to predict clinical coronary outcomes. EAT can also modulate cardiac structure and function. Its amount has been associated with atrial fibrillation, coronary artery disease, and sleep apnea syndrome. Conversely, a beiging fat profile of EAT has been identified. In this review, we describe the current state of knowledge regarding the anatomy, physiology and pathophysiological role of EAT, and the factors more globally leading to ectopic fat development. We will also highlight the most recent findings on the origin of this ectopic tissue, and its association with cardiac diseases. © 2017 American Physiological Society. Compr Physiol 7:1051-1082, 2017.