Wave Axis Research Articles

Modified torso vs distal limb electrode placement for performing ECGs in children: A method comparison study

BackgroundThe electrocardiogram (ECG) is routinely performed in children with the limb electrodes positioned on the torso, but few studies have investigated the effects of this modification on the pediatric ECG.Our objective was to assess the agreement between the standard limb lead configuration and a modified torso electrode configuration in normal, healthy children, and to assess the effect of height on that agreement. Methods185 children aged 5–18 years underwent two consecutive 12‑lead ECGs, one with standard distal limb lead placement and one with the limb leads placed on the torso. Agreement was assessed for 17 ECG parameters (intervals, axes, and amplitudes) using Bland-Altman plots, height-dependent mean error, and false positive rates. ResultsThe torso configuration systematically biased the QRS and P wave axes rightwards (towards aVF). Adequate agreement was observed for PR interval and QRS duration, but QTc limits of agreement (±40 ms) were wide. The torso configuration overestimated left-precordial Q, R, and S wave amplitudes and underestimated right-precordial R and S wave amplitudes compared to the distal limb placement. Mean measurement errors increased with the magnitude of the ECG parameter. Mean and variance of measurement errors were more pronounced in shorter children. False positive rates did not differ between the torso and distal limb configurations. ConclusionModified placement of the limb electrodes onto the torso resulted in multiple differences in the pediatric ECG signals. This may lead to misclassification of electrocardiographic abnormalities, particularly in children with measurement values at the upper limits of normal.

A novel electrocardiogram-based model for prediction of dementia: the Atherosclerosis Risk in Communities (ARIC) study

Abstract Background Current dementia prediction models, such as the UK Biobank Dementia Risk Score (UKBDRS, 12 variables), are limited by having variables that are difficult to obtain, subjectively measured, and self-reported. Although individual ECG parameters are linked to higher dementia risk, no study has combined multiple ECG parameters to create an ECG model for dementia prediction. Purpose Using data from the ARIC study, a prospective community-based cohort of Black and White participants in the USA that started in 1987-89, we created an ECG model (based on 7 pre-defined ECG parameters linked to dementia) and compared its model discrimination with the UKBDRS. Methods Participants without prevalent dementia from 2 baselines were included: Visit 4 (V4, 1996-98) and V5 (2011-13). Seven ECG parameters were examined: heart rate, abnormal P-wave terminal force in lead V1 (PTFV1), prolonged P wave duration, abnormal P wave axis, advanced interatrial block, left ventricular hypertrophy (LVH, Cornell voltage criteria), and corrected QT interval (QTc). Dementia cases were identified through 2019 using in-person and phone cognitive assessments, hospitalisation codes, and death certificates. Using a backward selection method (keeping variables with P<0.10 and age, since it is an important dementia risk factor), parsimonious Cox regression models were constructed for prediction of dementia over the longest available follow-up (V4: 23 years, V5: 8 years). Model discrimination of the ECG models and UKBDRS variables was evaluated by the Harrell’s C-statistic (95% CI). Results At V4, 11,520 participants (mean age, 62.8 ± 5.7 years; 56% women; 22% Black) were included; 2,427 developed dementia. At V5, 5,667 participants (mean age, 75.4 ± 5.1 years; 59% women; 22% Black) were included; 830 developed dementia. Figures 1 and 2 show the C-statistic (95%) and area under the ROC curve for the ECG model and UKBDRS variables at V4 and V5, respectively. The C-statistic (95% CI) for both ECG models were >0.70 and comparable with the corresponding UKBDRS models. Conclusion For middle-aged and older adults, a dementia prediction model comprising age and 4 ECG variables has good discrimination for dementia that is comparable with the 12-variable UKBDRS model. Since ECG variables are easily obtainable and objectively measured, these ECG models will be easier to adopt than the UKBDRS model. Further work to validate this model in an external cohort and develop a risk score will facilitate clinical translation.

Glucokinase activity controls subpopulations of β-cells that alternately lead islet Ca2+ oscillations.

Oscillations in insulin secretion, driven by islet Ca2+ waves, are crucial for glycemic control. Prior studies, performed with single-plane imaging, suggest that subpopulations of electrically coupled β-cells have privileged roles in leading and coordinating the propagation of Ca2+ waves. Here, we used 3D light-sheet imaging to analyze the location and Ca2+ activity of single β-cells within the entire islet at >2 Hz. In contrast with single-plane studies, 3D network analysis indicates that the most highly synchronized β-cells are located at the islet center, and remain regionally but not cellularly stable between oscillations. This subpopulation, which includes 'hub cells', is insensitive to changes in fuel metabolism induced by glucokinase and pyruvate kinase activation. β-cells that initiate the Ca2+ wave ('leaders') are located at the islet periphery, and strikingly, change their identity over time via rotations in the wave axis. Glucokinase activation, which increased oscillation period, reinforced leader cells and stabilized the wave axis. Pyruvate kinase activation, despite increasing oscillation frequency, had no effect on leader cells, indicating the wave origin is patterned by fuel input. These findings emphasize the stochastic nature of the β-cell subpopulations that control Ca2+ oscillations and identify a role for glucokinase in spatially patterning 'leader' β-cells.

Arrhythmias and electrocardiographic characteristics in cancer patients treated with immune checkpoint inhibitors

Objective: To evaluate the incidence of arrhythmias and electrocardiographic (ECG) characteristics in cancer patients treated with immune checkpoint inhibitors (ICIs). Methods: This was a cohort study conducted in the Fourth Hospital of Hebei Medical University. Cancer patients initiating ICIs treatments from November 2020 to September 2022 were included in this study. Baseline 12-leads ECG before ICIs initiation and post-treatment ECG were analyzed. An abnormal ECG was defined as the presence of any of the following changes: sinus arrhythmias, atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia, ventricular tachycardia, premature contractions, conduction disorder, and ST-T changes. Results: A total of 87 patients were enrolled, aged 63 (57, 68) years, with 66 (75.9%) males. And 44.8% (39/87) of patients presented with at least one confirmed cardiovascular disease or cardiovascular risk factor at baseline. The incidence of abnormal ECG increased from 31.0% (27/87) at baseline to 65.5% (57/87) after receiving (5.0±2.7) cycles of ICIs treatment (P<0.001). The incidence of sinus arrhythmias was significantly increased after ICIs treatment (23.0% (20/87) vs. 9.2% (8/87), P=0.023), of which only the incidence of sinus tachycardia was significantly increased (11.5% (10/87) vs. 2.3% (2/87), P=0.039). There was also a significantly increased incidence of ST-T changes after ICIs treatment (31.0% (27/87) vs. 17.2% (15/87), P=0.012), which mainly attributed to the T wave changes (29.9% (26/87) vs. 13.8% (12/87), P=0.001). The incidence of premature contractions was also significantly increased after ICIs treatment (9.2% (8/87) vs. 0, P=0.008). Additionally, compared with baseline, the P wave axis was significantly increased after ICIs treatment ((56.94±21.01)° vs. (52.00±22.69)°, P=0.043). After ICIs treatment, the heart rate was significantly increased ((79.07±15.37) beats/min vs. (75.64±13.37) beats/min, P=0.029). Sokolow-Lyon index ((2.21±0.81)mV vs. (2.33±0.75)mV, P=0.138), QTc interval ((431.44±36.04)ms vs. (428.00±30.05)ms, P=0.415) all showed signs of change after treatment, but did not reach the traditional significant level. Conclusions: The incidence of abnormal ECG is significantly increased after ICIs treatment, especially for sinus tachycardia, premature contractions and T wave changes; the P wave axis and heart rate is also significantly increased after treatment. It is important to perform regular ECG monitoring in patients receiving ICIs treatment.

Do athletic ECG changes predict athletic performance in Gurkha recruits?

IntroductionECG changes are associated with regular long-term intensive exercise due to electrical manifestations of increased vagal tone, increased ventricular wall thickness and enlarged chamber size. The aim of this study...

An interesting electrocardiogram caused by lead reversal

BackgroundDuring normal sinus rhythm, atrial depolarization is conducted from right atrium to left atrium through Bachmann’s bundle, and a normal P wave axis which is measured on the frontal plane is between 0º and + 75º. The change of P wave polarity is helpful for the analysis of origin point.Case presentationWe report a patient with negative P wave in lead I. The characteristics of QRS complex in leads V1 to V6 are helpful to preliminarily differential diagnosis. The 12-lead electrocardiogram (ECG) with correct limb leads (right arm-left arm) placement shows sinus rhythm with complete right bundle branch block (RBBB).ConclusionsThe change of P wave polarity as well as characteristics of QRS complex can help identify limb-lead reversals.

Is left bundle branch pacing (LBBP) associated with better depolarization and repolarization kinetics than right ventricular mid septal pacing (RVSP)? - Comparison of frontal QRS -T angle in patients with LBBP, RVSP and normal ventricular conduction

AimsTo assess the frontal QRS- T angle (f QRS- T angle) in patients with left bundle branch pacing (LBBP) as compared to right ventricular mid septal pacing (RVSP) implanted for symptomatic high degree atrioventricular (AV) block and to compare with control subjects with normal ventricular conduction (CSNVC) MethodsA total of one-fifty subjects were chosen (50 patients with LBBP, 50 patients with RVSP and 50 CSNVC). The indication for pacemaker implantation was symptomatic high degree AV block. Baseline clinical and electrocardiogram (ECG) parameters like QRS duration (QRSD), QRS axis and f QRS-T angle and Ejection Fraction (EF) were assessed. f QRS-T angle was measured as the difference between the computerised mean frontal QRS and T wave axes in the limb leads. If the difference between the QRS axis and T-wave axis exceeds 180°, then the resultant QRS-T angle would be calculated as 360° minus the absolute angle to obtain a value between 0° and 180°. Baseline, immediate post procedural and 6 month follow up (f/u) ECGs and EF were chosen for the analysis. ResultsPatients who underwent LBBP had significantly shorter paced QRSD than patients who had undergone RVSP (112 ± 12 ms vs 146 ± 13 ms; 95 % confidence interval (CI): 43, −31; p<0.001). There was no significant difference in the QRSD before and after LBBP. The QRSD before and after pacing in RVSP was 111 ± 27 ms and 146 ± 13 ms; 95 % CI: 43, −28; p < 0.001. The QRSD in control patients with NVC was 82.94 ± 9.59 ms.RVSP was associated with wider f QRS-T angle when compared with LBBP (103 ± 53° vs 82 ± 43°; 95 % CI: 39, −1.0; p = 0.037). The baseline and immediate post procedure f QRS-T angle in LBBP was 70 ± 48° and 82 ± 43°; 95 % CI: 31, 5.3; p = 0.2. At 6 months f/u, the f QRS-T angle was 61 ± 43°; 95 % CI: 8.5, 35; p=0.002. The baseline and immediate post procedure f QRS-T angle in RVSP was 67 ± 51° and 103 ± 53°; 95 % CI: 54, −17; p < 0.001. At 6 months f/u, the f QRS-T angle in RVSP group was 87 ± 58°; 95 % CI: 2.6, 29; p = 0.020. The f QRS T angle in control patients with NVC was 24 ± 16°. When subgroup analysis was done the difference in the f QRS-T angle was significant between RVSP and LBBP groups only in patients who had wide QRS escape.The mean LVEF at 6-month follow-up in LBBP vs RVSP was 61 ± 3.7 % vs 57.1 ± 7.8 %; 95 % CI:1.48, 6.32, p = 0.002. In the RVSP group, three patients developed pacing induced cardiomyopathy (PIC) whereas no patients in the LBBP group developed PIC at 6-month follow-up; p=0.021. One patient with PIC had deterioration of functional status with new onset HF symptoms. The patient symptoms improved with medical therapy and needed no hospitalisation. The patient declined further interventions including upgradation to CRT or LBB pacing. No deaths or ventricular arrhythmias were observed during the study period. ConclusionLBBP is associated with narrower f QRS-T angle as compared to RVSP both at post implant period and at 6 month f/u period. These findings might be due to the more physiological depolarization and repolarization kinetics associated with LBBP. RVSP was associated with 6 % incidence of PIC. Hence wide f QRS-T angle might be a predictor of PIC.

Abstract 15650: Recovery of Cardiomyopathy Following Accessory Pathway Ablation

Background: Wolf-Parkinson-White (WPW) can cause significant arrhythmia in addition to left ventricular (LV) dessynchrony and cardiomyopathy, which may be reversible by accessory pathway ablation. Case: A 21-year-old female athletics major college student presents with dyspnea, fatigue and occasional palpitations associated with dizziness. Electrocardiogram (EKG) revealed WPW with left bundle branch block pattern suggestive of right-sided bypass tract (panel A). Transthoracic echocardiogram (TTE) revealed LV ejection fraction (LVEF) 35 - 40% and significant interventricular dessynchrony on M-mode (panel B). Decision-making: It was felt that her symptoms and LV dysfunction are due to QRS widening and possibly arrhythmia caused by the bypass tract, and that ablation is warranted. Electrophysiology study 3-D map revealed 2 insertion points of the bypass tract along the tricuspid annulus (panel C). Ablation was performed initially along the inferior tricuspid annulus, leading to QRS complex narrowing with a change in the delta wave axis. Another activation site was mapped separately to the anterolateral tricuspid annulus; ablation at this site eliminated pre-excitation altogether. Post procedure EKG revealed normalization of the PR interval and diffuse T wave abnormalities likely due to cardiac memory (panel D). Follow-up in 6 weeks revealed an LVEF of 60 - 65% and normal wall motion on TTE with improvement of her symptoms; she was cleared to resume sports. Conclusion: WPW can be associated with significant cardiomyopathy and heart failure due both to arrhythmia and marked LV dessynchrony, which may be reversed by radiofrequency ablation.

A large population-based study on the prevalence of electrocardiographic abnormalities: A result of Mashhad stroke and heart atherosclerotic disorder cohort study.

Twelve-lead electrocardiogram (ECG) is a common and inexpensive tool for the diagnostic workup of patients with suspected cardiovascular disease, both in clinical and epidemiological settings. The present study was designed to evaluate ECG abnormalities in Mashhad population. ECGs were taken as part of MASHAD cohort study (phase1) and were coded according to the Minnesota coding criteria. Data were analyzed using SPSS. Total 9035 ECGs were available for final analysis including 3615 (40.0%) male and 5420 (60.0%) female. Among ECG abnormalities precordial Q wave, major T-wave abnormalities, inferior Q wave, sinus bradycardia, and left axis deviation were the most prevalent abnormalities. The frequency of precordial and inferior Q wave, inferior QS pattern, major and minor ST abnormalities, major and minor T abnormalities, Wolff-Parkinson-White and Brugada pattern, sinus bradycardia, sinus tachycardia, left axis deviation, ST elevation, and tall T wave were significantly different between two genders. Moreover, the frequency of Q wave in precordial and aVL leads, QS pattern in precordial and inferior leads, major and minor T-wave abnormalities, Wolff-Parkinson-White, atrial fibrillation, sinus bradycardia, left axis deviation, and ST elevation were significantly different in different age groups. A comparison of the heart rate, P-wave duration, and QRS duration between men and women indicated that there was a significant difference. Our finding indicated that the prevalence ECG abnormalities are different between men and women and also it varied in different age groups.

Artificial Intelligence-Enabled Electrocardiography Detects B-Type Natriuretic Peptide and N-Terminal Pro-Brain Natriuretic Peptide.

BACKGROUND: The B-type natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (pBNP) are predictors of cardiovascular morbidity and mortality. Since the artificial intelligence (AI)-enabled electrocardiogram (ECG) system is widely used in the management of many cardiovascular diseases (CVDs), patients requiring intensive monitoring may benefit from an AI-ECG with BNP/pBNP predictions. This study aimed to develop an AI-ECG to predict BNP/pBNP and compare their values for future mortality. METHODS: The development, tuning, internal validation, and external validation sets included 47,709, 16,249, 4001, and 6042 ECGs, respectively. Deep learning models (DLMs) were trained using a development set for estimating ECG-based BNP/pBNP (ECG-BNP/ECG-pBNP), and the tuning set was used to guide the training process. The ECGs in internal and external validation sets belonging to nonrepeating patients were used to validate the DLMs. We also followed-up all-cause mortality to explore the prognostic value. RESULTS: The DLMs accurately distinguished mild (≥500 pg/mL) and severe (≥1000 pg/mL) an abnormal BNP/pBNP with AUCs of ≥0.85 in the internal and external validation sets, which provided sensitivities of 68.0-85.0% and specificities of 77.9-86.2%. In continuous predictions, the Pearson correlation coefficient between ECG-BNP and ECG-pBNP was 0.93, and they were both associated with similar ECG features, such as the T wave axis and correct QT interval. ECG-pBNP provided a higher all-cause mortality predictive value than ECG-BNP. CONCLUSIONS: The AI-ECG can accurately estimate BNP/pBNP and may be useful for monitoring the risk of CVDs. Moreover, ECG-pBNP may be a better indicator to manage the risk of future mortality.

ECG characteristics associated with adverse outcomes in COVID-19, a tertiary centre experience

Abstract Funding Acknowledgements Type of funding sources: None. Background COVID-19 is a systemic disease with dominantly respiratory symptoms, however numerous other presentations involving practically any organ system have been described. Older patients and those with other comorbidities are at higher risk for critical COVID, increased respiratory requirements and death. (1) Those with cardiovascular comorbidities seem to be at a particular risk of detrimental outcomes. (2) Purpose The aim of our research was to see if certain ECG characteristics at admission could be predictive of unfavourable events in severe and critical COVID-19 patients. Methods We analyzed patient data and available ECG records at admission for 1752 consecutively hospitalized patients with severe and critical COVID-19 at our institution from March 2020 to June 2021. ECG records were obtained from our institution's medical archives, while patient data and outcomes were analyzed through electronic medical records. We analyzed the available ECGs recorded at admission for rhythm abnormalities, heart rate, ST segment changes, presence and localisation of Q waves, interventricular conduction abnormalities, AV conduction, PR, QRS and QTc interval duration, P, QRS and T wave axis, QRS-T angle and Sokolow-Lyon hypertrophy criteria. We defined primary outcomes as mechanical ventilation requirement and intrahospital death. Results Our results show that patients who required mechanical ventilation were significantly (P&amp;lt;0.05) more likely to have atrial fibrillation at admission, be tachycardic, have ST depression, have prolonged PR and QTc intervals, as well as pathological T wave axis and QRS-T angle. In multivariate analysis atrial fibrillation (OR 1.55, CI 1.07-2.23), tachycardia (OR 1.45, CI 1.17-1.80), prolonged PR interval (OR 1.88, CI 1.12-3.15) were independently associated with increased need for mechanical ventilation. Intrahospital mortality was significantly (P&amp;lt;0.05) increased in patients who had atrial fibrillation, were tachycardic, had ST depression or elevation, right bundle branch block, left bundle branch block, prolonged PR interval and QRS duration, short and long QTc interval, pathological T wave axis and QRS-T angle. Following multivariate adjustment, atrial fibrillation (OR 2.30, CI 1.59-3.32), tachycardia (OR 1.30, CI 1.05-1.61), ST depression (OR 1.91, CI 1.34-2.72), prolonged PR interval (OR 2.55, CI 1.53-4.25), short QTc interval (OR 8.64, CI 0.95-78.57) and pathological T wave axis (OR 0.71, CI 0.47-1.07) and QRS-T angle (OR 1.85, 1.25-2.73) independently significantly increased mortality. Conclusion Specific ECG changes seen already at admission seem to be associated with the need for mechanical respiratory support and increased mortality in COVID-19 patients. This readily available and easily utilised method can potentially help in early identification of those at risk in order to monitor patients more carefully and potentially alter early treatment approach.

Predicting risk of AF in ischaemic stroke using sinus rhythm ECG abnormalities: A meta-analysis.

To identify ECG changes in sinus rhythm that may be used to predict subsequent development of new AF. We identified prospective and retrospective cohort or case control studies evaluating ECG patterns from a 12-lead ECG in sinus rhythm taken in hospital or community predicting subsequent development of new AF. For each identified ECG predictor, we then identify absolute event rates and pooled risk ratios (RR) using an aggregate level random effects meta-analysis. We identified 609,496 patients from 22 studies. ECG patterns included P wave terminal force V1 (PTFV1), interatrial block (IAB) and advanced interatrial block (aIAB), abnormal P wave axis (aPWA), PR prolongation and atrial premature complexes (APCs). Pooled risk ratios reached significance for each of these; PTFV1 RR 1.48 (95% CI 1.04-2.10), IAB 2.54 (95% CI 1.64-3.93), aIAB 4.05 (95% CI 2.64-6.22), aPWA 1.89 (95% CI 1.25-2.85), PR prolongation 2.22 (95% CI 1.27-3.87) and APCs 3.71 (95% CI 2.23-6.16). Diabetes reduced the predictive value of PR prolongation. APC and aIAB were most predictive of AF, while IAB, PR prolongation, PTFV1 and aPWA were also significantly associated with development of AF. These support their use in a screening tool to identify at risk cohorts who may benefit from further investigation, or following stroke, with empirical anticoagulation.

PO-01-074 USE OF ELECTRO-ANATOMIC MAPPING TO REDUCE THE NUMBER OF LEAD DEPLOYMENT ATTEMPTS FOR OPTIMAL LEFT BUNDLE AREA PACING: A CASE SERIES

Left bundle area pacing (LBP) often requires multiple lead deployments into the interventricular septum to find an ideal site with left bundle capture. Evaluate the use of 3-dimensional electro-anatomical mapping system (3D map) to aid in the identification of the correct implant site to achieve optimal left bundle branch capture. Three consecutive patients requiring pacing for AV block with LVEF 40-45% are included in this case series. After ultrasound-guided axillary vein access, a decapolar catheter was advanced and visualized using Carto (DecaNav, Biosense Webster). Intracardiac anatomy was defined using fast activation mapping in the region of the bundle of His and right ventricular septum. High- and low-output pacing was delivered from each of the electrode pairs of the decapolar catheter while it abutted the septum. Ideal deployment site was chosen from among the electrode pair sites based on W-pattern in V1, R wave axis in inferior leads, and aVL/aVR relationship. After this site was marked on the 3D map, the catheter was removed and the pacing lead (Biotronik Solia S60) was advanced under 3D mapping guidance and deployed. Please see Table 1 for patient characteristics and procedure details. Please see figure for EAM Utilization of 3D mapping to select the ideal site of LBP capture can allow for (1) improved procedural efficiency, (2) decreased fluoroscopy usage, and (3) successful LBP capture with a single deployment.Tabled 1Patient characteristics and Procedure detailsPatient 1Patient 2Patient 3Age (years)645577GenderMaleMaleFemaleBody Mass Index (Kg/m2)273421Number of implant attempts111Fluoroscopy time2 minutes 25 secs1 min 47 secs2 minutes 50 secsComplicationsNoneNoneNone Open table in a new tab

Actual conditions of atrial septal lead implantation and the factors related to successful implantation

BackgroundPacemaker leads were originally implanted into the right atrial appendage (RAA) and right ventricular apex, but septal pacing, which is more physiological, is becoming increasingly popular. The usefulness of atrial lead implantation in the RAA or atrial septum is inconclusive, and whether or not atrial septum implantation is accurate has not yet been verified. MethodsPatients who underwent pacemaker implantation between January 2016 and December 2020 were included. The success rate of atrial septal implantation was validated using thoracic computed tomography performed for any reason postoperatively. We examined factors related to the successful implantation of the atrial lead in the atrial septum. ResultsForty-eight people were included in this study. Lead placement was performed with a delivery catheter system (SelectSecure MRI SureScan; Medtronic Japan Co., Ltd., Tokyo, Japan) in 29 cases and a conventional stylet in 19 cases. The mean age was 74 ± 12 years old, and 28 (58%) were male. Successful atrial septal implantation was performed in 26 patients (54%), with only 4 (21%) successful implantations in the stylet group. There were no significant differences in the age, gender, body mass index (BMI), pacing P wave axis, duration, or amplitude between the atrial septal implantation group and non-septal groups. The only significant difference was for delivery catheter use [22 (85%) vs. 7 (32%), p < 0.001]. In multivariate logistic analysis, the use of a delivery catheter was independently associated with successful septal implantation [odds ratio (OR): 16.9, 95% confidence interval 3.0–90.9] after adjusting for the age, gender, and BMI. ConclusionThe success rate of atrial septal implantation was very low at 54%, and only the use of a delivery catheter was associated with successful septal implantation. However, even with a delivery catheter, the success rate was 76%, so further investigations are warranted.

Electro-Mechanical Alterations in Atrial Fibrillation: Structural, Electrical, and Functional Correlates.

Atrial fibrillation is the most common arrhythmia encountered in clinical practice affecting both patients' survival and well-being. Apart from aging, many cardiovascular risk factors may cause structural remodeling of the atrial myocardium leading to atrial fibrillation development. Structural remodelling refers to the development of atrial fibrosis, as well as to alterations in atrial size and cellular ultrastructure. The latter includes myolysis, the development of glycogen accumulation, altered Connexin expression, subcellular changes, and sinus rhythm alterations. The structural remodeling of the atrial myocardium is commonly associated with the presence of interatrial block. On the other hand, prolongation of the interatrial conduction time is encountered when atrial pressure is acutely increased. Electrical correlates of conduction disturbances include alterations in P wave parameters, such as partial or advanced interatrial block, alterations in P wave axis, voltage, area, morphology, or abnormal electrophysiological characteristics, such as alterations in bipolar or unipolar voltage mapping, electrogram fractionation, endo-epicardial asynchrony of the atrial wall, or slower cardiac conduction velocity. Functional correlates of conduction disturbances may incorporate alterations in left atrial diameter, volume, or strain. Echocardiography or cardiac magnetic resonance imaging (MRI) is commonly used to assess these parameters. Finally, the echocardiography-derived total atrial conduction time (PA-TDI duration) may reflect both atrial electrical and structural alterations.

Ectopic atrial rhythm after superior septal approach to the mitral valve - an often under-reported entity.

Very few reports elaborate on the changes in P wave following superior septal approach to the mitral valve. We aimed to describe the changes in the P wave axis and other electrocardiographic changes following this approach among patients preoperatively in sinus rhythm. We did a retrospective review of medical records among all our patients undergoing superior septal approach for mitral valve surgery from September 2014 to September 2019. Electrocardiograms during hospital stay and until 6-month follow-up were analyzed. A deviation in P wave axis from the normal range of + 30 to + 60° was classified as ectopic atrial rhythm. In the study population of 47 patients (age 16-75years, 51.3 ± 13.6years; M:F ratio 3.7:1), who were in normal sinus rhythm preoperatively, 34 patients (72.3%) had a visible P wave on electrocardiogram (ECG) at discharge. Among them, the P wave axes of 17 patients (36.2%) were within normal range (normal sinus rhythm), whereas 17 patients (36.2%) had ectopic atrial rhythm at discharge. The most frequent abnormal P wave axis was between 0 and - 30° (12 patients). At 6months, 8 patients (17.0%) had a persistent ectopic atrial rhythm. These patients underwent a Holter test at 6months and were followed up for symptomatic bradycardia for 3years. None of the patients with ectopic atrial rhythm required pacemaker insertion. Persistence of ectopic atrial rhythm at 6months is common (17%) after superior septal approach. Documentation of P wave axis after this approach will help avoid missing it. These patients may be kept on follow-up to look for symptomatic bradycardia.

The frontal planar QRS/T angle in patients with non-ischemic type late gadolinium enhancement on cardiac magnetic resonance.

Evaluation of myocardial fibrosis may offer an insight into underlying pathological mechanisms of ventricular arrhythmias. We intended to investigate the possible association between the presence and extent of myocardial fibrosis and ventricular repolarization heterogeneity based on frontal planar QRS/T angle. We retrospectively investigated patients in whom gadolinium-based contrast agent cardiac magnetic resonance imaging was performed due to the suspicion of any myocardial disease. Patients with non-ischemic type late gadolinium enhancement (LGE) were enrolled into this study. The association between presence and extent of myocardial LGE and frontal planar QRS/T angle defined as the absolute difference between QRS wave axis and T-wave axis on a resting 12-lead surface ECG was evaluated. The frontal planar QRS/T angle was significantly higher in patients with myocardial fibrosis indicated by LGE compared to those without LGE (61.67 ± 40.70 vs. 37.27 ± 32.35, p < 0.001). LGE extent score assessed by visual 17-segment model was the only independent variable, which had a significant effect on frontal planar QRS/T angle [Unstandardized Coefficients B = 4.052, 95% CI [(2.025) - (6.079), p < 0.001]. In conclusion, this study showed that inhomogeneous areas of myocardium due to varying degrees of myocardial fibrosis might affect the electrical activity of the left ventricle, even with normal left ventricular dimensions and function.

The predictive value of abnormal P-wave axis for the detection of incident atrial fibrillation: A systematic review with meta-analysis.

There is growing interest in the prediction of incident atrial fibrillation (AF). The 12-lead electrocardiogram (ECG) has been a particularly rich target for possible prediction strategies. The P-wave axis is an ECG parameter that reflects the dominant vector of atrial depolarisation and is usually 0° -75°. There is a large body of literature suggesting that AF reflects structural and conduction abnormalities of the atria, and thus the P-wave axis may represent a sensitive parameter to detect such changes. A systematic review and meta-analysis of published literature associating abnormal P-wave axis and the development of incident AF was performed. Electronic databases were systematically searched from inception to October 2021. A random-effects model with generic inverse variance weights was utilised to pool the most adjusted effect measure from each paper. A funnel plot was used to assess publication bias. After excluding duplicate studies, 568 studies were screened. A total of eleven studies were identified that associated an abnormal P-wave axis with the subsequent detection of AF. The eight studies that considered abnormal P-wave axis as being <0° or >75° were pooled for meta-analysis. In the pooled studies a total of 78,222 patients were included with 5656 cases of incident atrial fibrillation identified. The meta-analysis of the studies suggested that an abnormal P-wave axis was associated with a pooled risk ratio of 2.12 (95% CI 1.49 to 3.01) for the detection of incident atrial fibrillation. This comprehensive systematic review and meta-analysis, indicates the positive association of abnormal P wave axis and future detection of AF. Utilisation of abnormal P-wave axis, alongside other parameters, may allow clinicians to better risk-stratify individuals at increased risk of AF, and thus identify those who may benefit most from prolonged cardiac monitoring or targeted anticoagulation.

Abstract 13420: Association of Digital ECG Biomarkers With Heart Failure Status

Introduction: Electrocardiography (ECG) may be useful as an adjunct method for evaluating heart failure (HF) severity, but few studies have systematically examined the electrocardiographic parameters associated with heart failure volume status. This may include effects of hypervolemia on thoracic impedance, autonomic function, and subendocardial ischemia. We hypothesized that ECG parameters related to these mechanisms co-vary over time with brain natriuretic peptide, a measure of HF severity. Methods: A retrospective cohort was obtained from the Emory Clinical Data Warehouse for patients who had &gt;2 ECGs performed &gt;3 days apart and repeated BNP measures within 24 hours of each ECG. We quantified the change in HF status by calculating the differences in BNP value between each ECG acquisition time point. A total of 37 metrics were extracted from digitized ECGs as primary predictors and evaluated using multiple linear regression. Results: We evaluated 10,376 pairs of ECGs from 7,171 unique patients. The mean age was 66.9 years, 48% were women, and 51.4% were black . The median absolute change in BNP over time was 178 pg/mL (IQR 52-532), and the median sampling interval was 106 days (IQR 27-357). We evaluated interval, duration, and axis metrics from the P, QRS, and T vectors from the raw digital ECG and found 8 co-varied with BNP changes, including heart rate, P wave axis, QRS amplitude, QRS duration, QRS axis, ST segment, T wave amplitude, and frontal T wave axis (see table). Conclusions: We found several ECG metrics that quantify autonomic activity, depolarization, and repolarization associated with changes in HF status as measured by BNP. These findings may help to understand the downstream effects of hypervolemia on cardiovascular risk and also understand the potential role for certain ECG metrics in helping determine volume status, especially in low-resource settings not offering BNP.

Abstract 11580: Clinical Validation of a Smartphone Compatible 6L Electrocardiogram Device in Ambulatory Patients

Introduction: Novel ECG devices seek to facilitate easier obtainment of ECG recordings, while not compromising accuracy, compared to a standard clinical 12-L ECG. We aimed to compare the accuracy of the AliveCor Kardia 6L device with simultaneously recorded 12-L ECG recording with the patient in the same position. Hypothesis: The AliveCor Kardia 6L ECG device demonstrates data highly correlated with a standard 12-L ECG. Methods: We included patients seen in an outpatient cardiology clinic. ECG data using the Kardia 6L and a standard 12-L were obtained simultaneously in the seated position. Median beats for each method were compared using Pearson’s correlation. Results: One hundred patients (mean age 57±18, 55% female) were included. Lead aVL R wave amplitude (r= 0.99), T wave amplitude (r= 0.99), T wave axis (r= 0.96) QRS axis (r= 1.00), QRS duration (r= 0.94), and QT duration (r= 0.96) demonstrated excellent correlation between the two methods (Figure). Conclusion: The 6L Kardia device allows for accurate ECG measurements in ambulatory patients. This illustrates implications for the diagnosis of cardiac diseases, including left ventricular hypertrophy, in both clinical and nonclinical settings.