Standard ECG Research Articles

Monitoring the health of patients using a nodal potential map

Purpose: The article presents the developed device and methods for monitoring the heart's condition using a nodal potential map. The proposal enables monitoring of the patient's health condition. Methods: Testing the heart's electrical activity in our device's case uses a "nodal potential map" BSPM (Body Surface Potential Mapping) technique. This is an extended version of the standard ECG measurement, which, instead of 12 leads, uses several dozen or even several hundred measurement electrodes placed in appropriate locations on the front and back of the chest. Results: The developed solution enables monitoring of heart function in a noninvasive way and is more precise than a standard ECG test. The collected measurements allowed us to determine the health and condition of the patient's heart—no anomalies were detected during its operation. Discussion: The next stage of work will be the development of machine learning algorithms trained on the measurements obtained from the vest. The results obtained so far indicate the potential of models classifying heart diseases.

A stroke patient with an unusual electrocardiogram

We present a case of a 70 year old man with a history of paroxysmal atrial flutter who was admitted to the hospital with symptoms and imaging consistent with an acute stroke. Physical exam was notable for a pulse rate of 50 beats per minute and right sided facial droop with mild dysarthria. Admission ECG shows a junctional bradycardia with evidence of dual AV node physiology, rarely manifested in a retrograde fashion on a standard ECG. The patient likely experienced parasympathetic sinus node slowing in the setting of acute stroke. During post-stroke monitoring, the patient demonstrated return of sinus rhythm with chronotropic competence and he had no additional arrhythmia during admission.

Handheld 6-Lead ECG for Early Detection of Acute Inferior Wall ST-T Segment Elevation Myocardial Infarction: HINT-MI Study Design and Rationale.

Background: ST-T segment elevation myocardial infarction (STEMI) is a critical condition that requires rapid diagnosis and treatment. Recently, various ECG recording devices have been developed. In this study, we aim to determine the utility of a 6-lead handheld ECG recording device to shorten the time taken for the diagnosis of inferior wall STEMI. Methods and Design: HINT-MI is an investigator-derived, observational, prospective study that will evaluate the ability of a handheld 6-lead ECG device to diagnose acute inferior wall STEMI. Patients who have undergone coronary angiography for STEMI or for other reasons will be enrolled in the study. This study aims to evaluate sensitivity and specificity of a handheld 6-lead ECG device by the level of agreement with a standard 12-lead ECG for diagnosing inferior wall STEMI. Further, we will determine whether the use of the handheld device can reduce the time needed for reperfusion treatment through faster diagnosis. Conclusions: This study aims to investigate the feasibility of a handheld 6-lead ECG device for diagnosing inferior wall STEMI to reduce the time required to diagnose inferior wall STEMI and to allow timely treatment.

KardiaMobile 6L versus 12-lead ECG: Effects on clinic utilization time.

We aimed to study whether KardiaMobile 6L 30-second capture technology could shorten ECG collection time compared to standard 12L ECG without compromising data usability. A single-center, non-randomized trial was performed on patients presenting for follow-up visits to the electrophysiology (EP)clinic. Providers in the KardiaMobile 6L group were allowed to request a standard 12L if the 6L was deemed insufficient for clinical care. Room utilization times, defined as the time from medical assistant room entry to exit, were compared for each group. There were 100 patients in the study, with 50 in each arm. Average room utilization time for the 12L group and 6L groups were 10.33 ± 2.2and 7.27 ± 1.93 min, respectively (p < .001). In 8 (16%) visits for the 6L group, an additional 12L was requested. For EP follow-up visits, clinic utilization time was significantly reduced with the KardiaMobile 6L compared to the 12L ECG with infrequent need for an additional 12L.

Early Effects of Modern Radiotherapy for Lung Cancer on Endothelial Damage and Myocardial Fibrosis: A Prospective Single-Center Study.

Radiotherapy (RT) may have a cardiotoxic effect on the heart and cardiovascular system. Postulated mechanisms mediating these complications include vascular endothelium damage and myocardial fibrosis. The aim of our study was to assess endothelial damage and myocardial fibrosis in the early period after RT on the basis of cardiac biomarkers and in relation to the radiation dose applied to individual heart structures in patients treated for non-small-cell lung cancer. This single-center prospective study included consecutive patients with lung cancer (LC) who were referred for treatment with radiochemotherapy (study group) or chemotherapy (control group). The study protocol included performing an echocardiographic examination, a standard ECG examination, and collecting blood samples for laboratory tests before starting treatment for lung cancer in the first week after completing RT (after four cycles of chemotherapy in the control group) and after 12 weeks from the end of treatment. The study included 23 patients in the study group and 20 patients in the control group. Compared to the baseline values, there was a significant increase in total cholesterol concentration in the study group immediately after the end of RT, which persisted for three months after the end of therapy. After taking into account the use of statins in the analysis, it was found that an increase in total cholesterol concentration after oncological treatment was observed only among patients who did not use statins. Taking into account the assessment of myocardial fibrosis markers, there were no significant changes in the concentration of matrix metallopeptidase 9 (MMP-9) and tissue inhibitors of metalloproteinases 1 (TIMP-1) in the study group. In patients treated with radiochemotherapy, there was a significant increase in the concentration of intercellular adhesion molecule 1 (ICAM-1) immediately after RT, when compared to the baseline. After taking into account the use of statins, an increase in ICAM-1 concentration immediately after RT was observed only in patients who did not use statins. There was also a significant correlation between the radiation dose received by the left anterior descending coronary artery (LAD) and left circumferential coronary artery, and vascular cell adhesion protein 1 (VCAM-1) concentration measured at three months after the end of RT. Immediately after completion of radiotherapy, a significant increase in the level of ICAM-1 is observed indicating endothelial damage. The radiation dose to coronary arteries should be minimized, as it correlates with the concentration of VCAM-1. The use of statins may prevent the increase in total cholesterol and ICAM-1 concentration after irradiation for lung cancer; however, further studies designed for this specific purpose are necessary to confirm the effectiveness of statins in this area.

Erythrocyte aggregability, and fibrinogen during atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Academician N. Kipshidze University Clinic - Republican Hospital; IVANE BERITASHVILI CENTER OF EXPERIMENTAL BIOMEDICINE, Department of rheology and diagnostic analytical services. Introduction Despite all biomedical efforts, the prevalence of atrial fibrillation and its associated morbidity and mortality are increasing globally year after year. The disease's unfavorable epidemiological picture determined the reality of the project. There are many hypotheses to explain the pathogenesis of atrial fibrillation. All the hypotheses are based on mechanisms at local points and microwaves (in whole or in part). None of them consider the role of hemodynamics and hemorheology in the formation and progression of atrial fibrillation. It is also unknown how atrial fibrillation affects intracardiac macro- and microcirculation. Purpose The goals of this project were to determine how hemodynamics and hemorheology change in patients with atrial fibrillation. In order to gain a better understanding of the pathological processes underlying AF, we sought to access the relationships between hemodynamics, rheological properties,and the coagulation system of blood. Methods The Erythrocyte (RBC) Aggregation Index (EAI) was monitored in the development and validation cohorts (90 patients and 20 healthy individuals) using the textural analysis system (Tas-Plus, Leitz, Germany) and an innovative "Georgian technique" with the unique function of a quantitative assessment of the EAI. The method was developed by Georgian scientists and is well-known around the world for being direct, numerical, and precise. In all patients Coagulogram and 12-lead standard ECG were performed. Results According to the data obtained, the patients' rheological and coagulation system conditions are the same, and they are distinct from the control group. During the statistical processing of the total amount of fibrinogen (Fib), the patients were divided into three categories. The average Fib in Category I patients was 336.40 ±27,77 mg/dl, and the average EAI-RBC value was 32.8± 9.4. Category II: FIB: 373.00±22.65mg/dl; EAI-RBC: 39.8±13.8 and Category III: FIB:471.27±21.58 mg/dl; EAI-RBC: 42.6±10.4. The control group: FIB: 301±18,1 mg/dl, EAI-RBC: 25.6±1.29. Fibrinogen and the Index of Erythrocyte Aggregation were found to have a linear relationship. The higher the concentration of fibrinogen, the more severe the hemorheological disorders. It should be noted that the categories were chosen without taking into account the forms of atrial fibrillation. Conclusions The findings clearly show the existence of two parallel mechanisms in the body. These are the coagulation systems, characterized by dynamic equilibrium, and the rheology systems, which lack a physiologically balanced opposing system. Coagulation control does not accurately describe hemorheological parameters, which are one of the most powerful mechanisms for atrial fibrillation formation In order to better understand the diseases' occurrence and progression, the simultaneous studies of fibrinogen concentration and rheological parameters are especially important for both fundamental and practical medicine.

Characterization of a new arrhythmogenic cardiomyopathy mouse model due to filamin c haploinsufficiency

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Spanish Ministry of Universities FPU fellowship (FPU19/04044), Spanish Ministry of Science and Innovation Digital Transition call (TED2021-129774B-C22), EU HORIZON EIC Pathfinder Challenges 2022 Cardiogenomics call (Project 101115416). Background Filamin C (FLNC) is widely expressed in heart and skeletal muscle. It participates in cell junction and sarcomere assembly and function. We have previously shown that heterozygous FLNC truncating variants (FLNCtv) cause arrhythmogenic/dilated cardiomyopathy (ACM/DCM) in patients. Diverse studies have suggested haploinsufficiency as the potential mechanism of this disease. However, animal models of FLNCtv have only been reported to develop ACM/DCM in homozygosity. Purpose To develop a new model of ACM/DCM caused by a FLNCtv and study the progression of the disease in heterozygosity. Methods Two gRNAs flanking exon 15 of the Flnc gene and SpCas9 protein were microinjected into mouse zygotes to generate a mouse line with a constitutive deletion of Flnc exon 15 (FlncWt/Ex15del). mRNA and protein stability were determined by qRT-PCR and western blot, respectively. Cardiac function was analysed by ECG and echocardiography every 2 months, starting at 8 weeks of age (Fig. 1B). The mean ECG values were calculated using 3 time intervals and standard ECG waves. Results FlncWt/Ex15del mice showed a reduction in Flnc mRNA and protein similar to that observed in a human ACM/DCM patient bearing a similar mutation, suggesting that this FLNCtv causes haploinsufficiency. Both male and female FlncWt/Ex15del mice developed cardiac electrophysiological defects, including reduced amplitude of the QRS complex and the P-wave, notched R and/or S waves, and increased QT interval times, and these defects worsened with time. At 40 weeks of age, FlncWt/Ex15del mice showed some initial signs of left ventricular dilatation. Conclusions Mice carrying FLNCtv in heterozygosity develop electrophysiological changes resembling pathological features of ACM/DCM patients due to haploinsufficiency. The development of this pathological phenotype in heterozygosity, as opposed to previous models, paves the way for the development of new gene therapies using this model.

Performance of a vectorcardiographic deep learning algorithm compared to single-lead and 12-lead ECG for atrial flutter detection: implications for wearable devices

Abstract Background Wearable devices have developed the capacity to offer single-lead ECG analysis and are already widespread in use, particularly for detection of atrial fibrillation (1,2). Vectorcardiography entails the transformation of electrical vectors into X, Y, and Z axes to constitute a vectorcardiogram (VCG) (3). The VCG has diagnostic promise given the capacity to generate it without requiring clinical presentation for standard 12-lead ECG acquisition. Furthermore, a novel credit-card sized device capable of acquiring a VCG has recently been developed – raising the potential for arrhythmia detection and discrimination beyond wearable single-lead ECG systems. Objective To assess the performance of a deep learning algorithm trained on single lead and 12-lead ECGs and VCGs for detecting atrial flutter. Methods A convolutional neural network (AFL-CNN) was developed on a dataset of 4,000 ECGs and VCGs from a single US academic medical institution (80% training and 20% for testing). Validation was performed on a separate publicly available dataset (2223 ECGs). Model performance was assessed on single lead ECG analysis (lead I, obtained by removing the other leads) and standard 12-lead ECG. The gold standard for AFL diagnosis was physician-confirmed 12-lead ECG diagnoses in the dataset. The VCG was generated from the 12-lead ECG via Kors transformation matrix to which AFL-CNN was also applied. Model performance was assessed with sensitivity, specificity, positive and negative predictive values, accuracy, and F1 statistic. Results On single lead ECG analysis, AFL-CNN achieved 71.2% sensitivity and 96.9% specificity with PPV 84.0% and NPV 93.7% and 92.2% accuracy with F1 83.2%. When AFL-CNN was applied to the VCG, performance improved: 91.0% sensitivity and 98.7% specificity, PPV 94.24%, NPV 98.0%, 97.3% accuracy, and F1 95.31%. Lastly, the performance remained high when AFL-CNN was applied to the 12-lead ECG: 95.4% sensitivity, 98.63% specificity, PPV 94.0%, NPV 99.0%, and accuracy of 98.0%, with F1 97.2%. Conclusion A deep learning algorithm applied to vectorcardiography for the detection of atrial flutter showed improved performance over single lead analysis and comparable performance to standard 12-lead applications. The finding of improved model performance beyond single lead ECG tracings underscores both the limitations of current wearable technologies in arrhythmia detection beyond atrial fibrillation and the potential for VCG-based algorithm prediction to fill gaps in healthcare inequality when standard 12-lead acquisition is challenging to obtain.

CineECG analysis of body surface potential mapping performed in preclinical and clinical plakophilin-2-variant carriers

Abstract Background/introduction Pathogenic variation of the plakophilin-2 (PKP2) gene is associated with arrhythmogenic cardiomyopathy (ACM). Disease manifestation in PKP2-pathogenic variant (PV) carriers differs greatly. Early detection of disease is crucial and could be of benefit in the risk stratification of this population. 67-lead body surface potential mapping (BSPM) could offer more insight into subtle electrical abnormalities. CineECG is a novel tool which can provide an estimation of the average pathway of ventricular activation based on the BSPM-signals, and could be of added value in the detection of electrical abnormalities. Purpose This study aimed to analyze 67-lead BSPM data with CineECG to ascertain the electrical activation pathway in PKP2-PV carriers and to compare these to the normal CineECG. Methods Ten PKP2-PV carriers underwent 67-lead BSPM. Six carriers were without definite ACM diagnosis (preclinical); no Task Force Criteria (TFC) were met apart from the identification of the pathogenic PKP2-variant. The other four carriers were all diagnosed with definite ACM (symptomatic). The average location and direction of ventricular activation was determined with CineECG, resulting in a CineECG trajectory throughout the ventricles. These results were compared to the normal CineECG trajectory, which was established in a previous study with normal ECG’s from the PTB-XL database. A CineECG trajectory that deviated more than 15% from the normal trajectory was considered abnormal. Additionally, to further determine the added diagnostic value of BSPM and CineECG beyond the standard 12-lead ECG, the 12-lead ECG’s were evaluated for abnormalities by three different ECG-experts. Results Expert evaluation of the 12-lead ECG showed that all preclinical PKP2-PV carriers had a normal ECG (no TFC and no other abnormalities such as abnormal electrical heart axis, pathological Q-waves or low voltage). In the symptomatic carriers, all ECG’s showed either presence of TFC or conduction abnormalities. Of the ten PKP2-PV carriers, eight exhibited an abnormal CineECG trajectory. In the preclinical group, four out of six carriers had an abnormal activation trajectory, while all symptomatic carriers had an abnormal CineECG trajectory. Conclusions Through CineECG analysis of 67-lead BSPM, abnormal ventricular activation was identified in the majority of PKP2-PV carriers. Notably, abnormal activation was observed in four out of six preclinical PKP2-PV carriers while the standard 12-lead ECG showed no abnormalities. Future research in a larger group, which also includes follow-up data, is warranted to determine whether these results are an indication of early signs of disease.Figure 1

Potential determinants of nocturnal hypoxemic burden and its association with atrial fibrillation recurrence after catheter ablation

Abstract Background Sleep-disordered breathing (SDB) is present in approximately half of patients with atrial fibrillation (AF) scheduled for catheter ablation (CA) and coincides with an elevated nocturnal hypoxemia. Purpose To evaluate determinants of nocturnal hypoxemic burden metrics and its association with AF recurrence after CA in patients undergoing a systematic SDB management and treatment pathway. Methods Consecutive AF patients scheduled for CA without history of SDB and/or SDB screening were included. Patients were referred to a virtual SDB management pathway including mobile health supported overnight home sleep test. An apnoea-hypopnoea index (AHI) of 5 to &amp;lt;15 and ≥ 15 were interpreted as mild and moderate-to-severe SDB, respectively. Oximetry data from home sleep tests were analyzed by a computer algorithm to evaluate metrics of nocturnal hypoxemic burden: time spent below 90% oxygen desaturation (T90) based on acute desaturations (T90 desat) or non-specific drifts in oxygen desaturation (T90 non-spec). Patients were monitored for AF recurrences through standard 12-lead ECG or Holter ECG and/or smartphone-based photophletysmography (PPG) performed at 3- and 12-month follow up. Multiple regression analysis was employed to (1) evaluate determinants of nocturnal hypoxemic burden metrics and (2) identify predictors of AF recurrence during 12 months after CA (excluding 3 months blanking period). Results The analysis included 210 patients (42% female, mean age 64± 9 years). Median AHI was 14.7 [6.7-24.7], median T90desat was 0.25 [0.03-1.42] minutes, T90non-spec 0.26 [0.08-0.78] minutes. Overall, 101 (48%) patients were diagnosed with moderate-to-severe SDB and 68 (32%) had mild SDB. Of patients with moderate-to- severe SDB and mild SDB, 87% and 46%, respectively, received a SDB therapy recommendation. Multiple linear regression analysis identified diabetes mellitus (B 8.611 95%CI 1.350-15.871, p=0.020) and AHI ≥ 15 (B 5.886, 95%CI 1.793-9.979, p= 0.005) as predictors of T90non-spec. Thyroid dysfunction (B 1.849, 95%CI 0.623-3.075, p=0.003) and AHI ≥ 15 (B 2.161, 95%CI 1.320-3.001, p&amp;lt;0.001) were significant predictors of T90desat. During 12 months after CA, 65 (31%) patients had experienced at least one AF recurrence after the blanking period. After multiple Cox-regression, age (HR 1.032, 95%CI 1.002-1.063, p= 0.035) and BMI ≥ 25 (HR 2.029, 95%CI 1.032-3.989, p=0.040) remained predictors for AF recurrences. Conclusions In AF patients scheduled for CA, SDB (AHI ≥ 15) and thyroid dysfunction were predictors for nocturnal hypoxemic burden with repetitive desaturations (T90desat). SDB and diabetes mellitus were predictors for nocturnal hypoxemic burden without repetitive desaturations (T90non-spec). In patients with AF who followed a virtual SDB management and treatment pathway, SDB presence and nocturnal hypoxemic burden metrics did not emerge as predictors, whereas age and BMI (≥25) remained significant predictors for AF recurrence.

Recognition of Brugada type 1 pattern on ECG by Echo State Networks

Abstract Background/Introduction The development of artificial intelligence (AI) and machine learning (ML) techniques, which can identify data patterns in electrocardiography, has led to the development of automated analysis tools for standard 12-lead ECGs. These tools are able to identify specific features associated with different cardiac diseases, which may be helpful in clinical practice [1]. One field of application is represented by Brugada Syndrome (BrS) diagnosis, which, despite characteristic ECG features, can be challenging to diagnose and correctly distinguish from other diseases. Purpose Within the Brugada Syndrome and Artificial Intelligence Applications to Diagnosis system study, we are developing an innovative model for diagnosing Type 1 BrS based on electrocardiographic pattern recognition through the Echo State Networks (ESN), a Recurrent Neural Network (RNN) type of architecture. Methods From patients enrolled in 5 Centers, 306 12-lead ECGs were obtained. The datasets were composed of spontaneous Type 1 pattern (coved) (group A, 98 patients); patients undergoing ajmaline test, classified as positive (group B, 47 patients) or negative (group C, 35 patients) according to test results; 220 controls with no clinical and familial history of arrhythmias (group D). ESN analyzed, as input, data collected from 1 beat of the ECG V2 lead. The datasets were used for the ESN model training and were assessed through a double cross-validation approach. The ESN performance was compared with the evaluation of 4 independent cardiologists, and sensitivity, specificity and accuracy were determined. Results The ESN model correctly classified 280/306 ECGs (91.5%), with a performance of 3.6 points superior to clinicians (269/306, 88.0%). ESN sensitivity (87.0% vs. 86.9%) and specificity (94.5% vs. 89.1%) are described in Table 1; accuracy in each group of the dataset (groups A, B, C, and D), represented in Table 2, were comparable to or greater than those of clinicians. Conclusion(s) In this work, an ESN-based system for diagnosing Type 1 BrS pattern on ECG was developed. Our results show that this ML model can detect ECG patterns associated with Type 1 BrS with accuracy, sensitivity and specificity comparable or superior to clinicians. In the future, we will use a larger dataset to increase the model performance further, with the real possibility of becoming a tool for everyday clinical practice.ESN and clinicians' diagnostic accuracyECG accuracy in each dataset group

Additional factors associated with sudden cardiac death in HCM patients

Abstract Background Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease characterized by an increase in the thickness of the left ventricular (LV) wall, which is not explained only by abnormal loading conditions. Sudden cardiac death (SCD) is the most devastating complication of HCM occurring in asymptomatic or younger patients without warning. Purpose To evaluate additional SCD risk factors in Ukrainian population of HCM patients. Materials and methods We retrospectively evaluated 350 consecutive HCM patients that were followed from 2006 to 2021 in our Cardiological Department. General clinical examination, standard 12-lead ECG, transthoracic echocardiography and 24 hours Holter ECG monitoring data were estimated. The 5-year SCD risk was calculated according to the HCM Risk-SCD score. The endpoint of the study was SCD and its surrogates, including adequate performance of the implantable cardioverter-defibrillator and successful resuscitation. Results Follow-up time was 5.0 (1.5-9.5) years. During this time, 16 patients (4.6%) reached the end point, which was 0.9%/year. According to the HCM Risk-SCD score, 5 (31.3%) of this group had a high risk of SCD (≥ 6%) and 3 (18.8%) had an intermediate risk (≥ 4% and &amp;lt; 6%). In multivariable Cox regression analysis adjusted for conventional SCD risk factors it was found that independent predictors of SCD were unexplained syncope (HR 3.81, 95% CI 1.11-13.12, p=0.034), systolic blood pressure (SBP) (HR 0.97 , 95% CI 0.94- 0.99, p=0.026), "infarct-like" ST elevation on ECG (HR 6.81, 95% CI 2.09-22.16, p=0.001) and PQ interval duration (HR 1.03, 95% CI 1.01-1.05, p=0.002), Harrell's C-index 0.84, 95% CI 0.73-0.95, p &amp;lt; 0.0001). Conclusions In our study HCM Risk-SCD score predicted SCD or surrogates only in 50% of cases. In order to improve the risk stratification some additional independent predictors of SCD can be proposed. ECG parameters ("infarct-like" ST elevation and PQ interval duration) and level of SBP were found to have SCD predictive value.

High-resolution repolarization changes preceding short-coupled ectopy in idiopathic ventricular fibrillation, and effects of quinidine

Abstract Background Idiopathic ventricular fibrillation (VF) is linked to early repolarization, increased repolarization heterogeneity, and (short-coupled) premature ventricular complexes (PVCs). Quinidine, an antiarrhythmic drug with class-IA and -III effects, reduces the occurrence of PVCs and VF, but its effects on repolarization have not yet been studied at the whole-heart level in idiopathic-VF patients. Purpose To study dynamic changes in repolarization preceding short-coupled PVCs using noninvasive electrocardiographic imaging (ECGI) in a patient with idiopathic VF, and the antiarrhythmic effects of quinidine. Methods ECGI was performed during sinus rhythm in a 61-year-old male with an ICD (secondary prevention; 2.5 mg nebivolol daily) two days after recurrent idiopathic VF (Fig. A). This was done 1) at baseline, 2 minutes before short-coupled ectopy ("baseline"); 2) at baseline, 10 seconds before the short-coupled PVC ("pre PVC"); and 3) at 2 hours after start of quinidine 200 mg ("on-quinidine"). The ECGI procedure consisted of a 224-electrode body surface potential map and a contrast-enhanced CT scan to obtain torso and heart geometries. After reconstruction of epicardial unipolar electrograms (UEGs), local activation and repolarization times (ATs and RTs) were derived from UEGs by assessing the steepest downslope of the QRS complex and steepest upslope of the T waves, respectively, of 10-second signal-averaged beats. AT and RT duration (first to last AT or RT) were assessed. Results At baseline, QRS duration and QT interval measured 107 ms and 343 ms, respectively, on the standard 12-lead ECG. ECGI-derived epicardial AT duration was 72 ms, and RT histogram span 92 ms. The coupling interval of the PVC that triggered VF in the ICD readout was 340 ms (Fig. A). During 44 minutes of ECGI, 157 short-coupled PVCs from the moderator-band region were recorded (Fig. B; no tachycardia or VF). Just prior to a PVC, epicardial early repolarization at the PVC origin decreased by 26 ms (star in Figs. C-E), and the RT histogram broadened to 109 ms (Fig. E). While on-quinidine, (25 minutes; QRS duration 107 ms, QT interval 419 ms), epicardial repolarization was prolonged (Fig. C/D), also at the site of abnormal impulse formation. Quinidine had increased the epicardial AT duration to 79 ms, and RT histogram span to 133 ms. PVCs were completely suppressed. The patient remained free of sustained arrhythmias while on-quinidine. Conclusion(s) In this case of short-coupled idiopathic VF, epicardial early repolarization shortened momentarily prior to abnormal impulse formation. We found dynamic substrate-trigger characteristics that likely facilitate reentrant excitation. Quinidine prolonged the duration of epicardial activation and repolarization, suppressing the ectopy and VF recurrence.

Multicenter hemodynamic assessment of the LOT-CRT strategy: when is one lead enough for resynchronization?

Abstract Background Left bundle branch area pacing (LBBAP) has been postulated as an alternative to traditional cardiac resynchronization therapy via biventricular pacing (BiV) in heart failure patients with wide QRS. Limited data is available regarding the acute hemodynamic response of LBBAP and the combination of LBBAP and coronary venous (LVcv) pacing (LOT-CRT). Purpose We sought to compare the acute hemodynamic and ECG effects of traditional CRT (BiV or LV-only) versus LBBAP and LOT-CRT in CRT candidates with advanced conduction disease. Methods In this multi-centre study (5 EU and 7 US centres), 48 subjects (mean age 65.8 years, 67% males, LV ejection fraction 29.4%) with either nonspecific interventricular conduction delay (NIVCD, n = 29) or left bundle branch block (LBBB; n =19; based upon strict criteria AHA/ACC/HRS plus Strauss) underwent an acute hemodynamic study to determine the % change in +LV dP/dtmax from baseline atrial pacing versus BiV, LBBAP, or LOT-CRT. Each therapy pacing configuration was applied 4 times at 5 different atrioventricular (AV) delays. QRS shortening was assessed using standard 12-lead ECG. Results Successful LBBAP lead implantation was achieved in 27 patients (56%) using current EHRA criteria. Twenty-one patients (44%) were categorized as deep septal pacing (DSP), due to suboptimal lead penetration or advanced left conduction system disease with broad paced QRS complexes and absent V1-r-wave. The increase in AV-optimized dP/dtmax for the different pacing configurations is displayed in the Figure, left panel. LOT-CRT dP/dtmax % improvement was 25.8%, significantly higher than LBBAP configurations (p&amp;lt;0.01), either unipolar-LBBAP (19.3%), or bipolar-LBBAP (16.4%), but not different from BiV (26.4%). QRS shortening was greater in LOT-CRT (29.5ms) vs. unipolar-LBBAP (11.9ms), bipolar-LBBAP (11.7ms), or BiV (18.5ms), all p&amp;lt;0.01. Sub-group analysis indicated the hemodynamic benefit of adding LVcv pacing when LBBAP strategy was pursued (Figure, right panel) depended on obtaining LBBAP rather than DSP (p &amp;lt; 0.01) and baseline QRS duration (p = 0.03). The largest benefit was observed among subjects with a baseline QRS wider than the observed cohort mean (171ms) and DSP only, where LOT-CRT provided 14.5% (5.0-24.1%) greater dP/dtmax improvement and 20.8ms (12.8-28.8ms) greater QRS duration shortening than unipolar DSP. Conclusions In a CRT cohort with advanced conduction disease, LOT-CRT provided greater acute hemodynamic benefit than LBBAP strategy (i.e. including also DSP cases). Patients with wider QRS or suboptimal outcome of LBBAP strategy (DSP) are more likely to benefit from addition of a LVcv lead to implement LOT-CRT.Figure 1

Repolarization dynamics stability in Brugada type-1 pattern subjects with positive and negative genetics

Abstract Background Brugada type-1 pattern (Brgd1) risk stratification in asymptomatic subjects and its repolarization dynamics are complex. Purpose This study aims to analyze, from alternative standpoints, superficial 12-lead ECG V1 repolarization patterns (repol.). This method diverges from standard ECG pattern characterization. It rather exploits nonlinear dynamics and stability of ECG repol. to assess stability driving cardiac dynamics. This work consists in analyzing 2 subjects with Brgd1: Subject1 with negative genetics and negative EP study. Subect2 with positive genetics. Target To deepen knowledge/insight and applications of control-and-stability-theory applied to 12-lead ECG, aiming to eventually diminish the number of invasive EP studies. Methods A stability control closed loop system has been designed to model electrophysiology dynamics of cardiac conduction: ECG segments being the input-output of the system. (Figure). A sequence of V1 repol. have been scanned, digitized, and quantitatively processed yielding stability parameters (poles in S-plane). Scanning and signal processing performed by Matlab R_2023b. Results Figures. Conclusions Based on our data, 12-lead-ECG repol. seem to be associated with increasing stability in Subject1, exhibiting negative genetics. On the other hand, less stability seems to be associated with Subject2, reporting positive genetic tests. In conclusion, furthering control-and-stability-theory applied to 12-lead ECGs aims to deeper comprehension of physiological and pathological substrates of malignant arrhythmias, and to focus on noninvasive risk stratification strategies for ICD implantation indication in BrS. Further development of this technique will be largely facilitated by the implementation of AI methodologies in the near future.

Conditional generative adversarial network driven variable-duration single-lead to 12-lead electrocardiogram reconstruction

The standard 12-lead ECG can represent the cardiac status from twelve different perspectives, while the single-lead ECG just involves a single view, so it is challenging for the single-lead ECG to provide information as rich as the 12-lead ECG. Therefore, this study adopts the improved generative adversarial network (GAN) framework to model the potential mapping relation between single-lead and 12-lead ECG. Taking a heartbeat (1024 points) in lead I as input, in which the R-peak aligning strategy will be used for variable-duration reconstruction. The average correlation coefficients(CC) between the generated and the real signals are 0.742 at the heartbeat level and 0.744 at the segment level, and the CC in lead aVR could be up to 0.91 at the segment level. This study demonstrates that the generated 12-lead ECG signals effectively retain pathological features, thereby providing valuable multi-scale diagnostic information. To assess the efficacy of the diagnostic information derived from the generated signals, this study employs the arrhythmia classifiers for both single-lead and 12-lead ECG, achieving accuracy of 0.71 and 0.81, and macro-F1 scores of 0.66 and 0.77. For the generated 12-lead ECG, the accuracy and macro-F1 for arrhythmia classification could be 0.74 and 0.70, successfully bridging the gap between the single-lead ECG and the 12-lead ECG. In addition, the supplement experiments for other cases have been shown and compared. The source code is available at https://github.com/Zehui-Zhan/12-lead-reconstruction.git.

Artificial intelligence–based screening for cardiomyopathy in an obstetric population: A pilot study

Cardiomyopathy is a leading cause of pregnancy-related mortality and the number one cause of death in the late postpartum period. Delay in diagnosis is associated with severe adverse outcomes. To evaluate the performance of an artificial intelligence-enhanced electrocardiogram (AI-ECG) and AI-enabled digital stethoscope to detect left ventricular systolic dysfunction in an obstetric population. We conducted a single-arm prospective study of pregnant and postpartum women enrolled at 3 sites between October 28, 2021, and October 27, 2022. Study participants completed a standard 12-lead ECG, digital stethoscope ECG and phonocardiogram recordings, and a transthoracic echocardiogram within 24 hours. Diagnostic performance was evaluated using the area under the curve (AUC). One hundred women were included in the final analysis. The median age was 31 years (Q1: 27, Q3: 34). Thirty-eight percent identified as non-Hispanic White, 32% as non-Hispanic Black, and 21% as Hispanic. Five percent and 6% had left ventricular ejection fraction (LVEF) <45% and <50%, respectively. The AI-ECG model had near-perfect classification performance (AUC: 1.0, 100% sensitivity; 99%-100% specificity) for detection of cardiomyopathy at both LVEF categories. The AI-enabled digital stethoscope had an AUC of 0.98 (95% CI: 0.95, 1.00) and 0.97 (95% CI: 0.93, 1.00), for detection of LVEF <45% and <50%, respectively, with 100% sensitivity and 90% specificity. We demonstrate an AI-ECG and AI-enabled digital stethoscope were effective for detecting cardiac dysfunction in an obstetric population. Larger studies, including an evaluation of the impact of screening on clinical outcomes, are essential next steps.

A Collaborative Platform for Advancing Automatic Interpretation in ECG Signals.

Numerous papers report the efficiency of the automatic interpretation capabilities of commercial algorithms. Unfortunately, these algorithms are proprietary, and academia has no means of directly contributing to these results. In fact, nothing at the same stage of development exists in academia. Despite the extensive research in ECG signal processing, from signal conditioning to expert systems, a cohesive single application for clinical use is not ready yet. This is due to a serious lack of coordination in the academic efforts, which involve not only algorithms for signal processing, but also the signal acquisition equipment itself. For instance, the different sampling rates and the different noise levels frequently found in the available signal databases can cause severe incompatibility problems when the integration of different algorithms is desired. Therefore, this work aims to solve this incompatibility problem by providing the academic community with a diagnostic-grade electrocardiograph. The intention is to create a new standardized ECG signals database in order to address the automatic interpretation problem and create an electrocardiography system that can fully assist clinical practitioners, as the proprietary systems do. Achieving this objective is expected through an open and coordinated collaboration platform for which a webpage has already been created.

Ultra-high-frequency ECG volumetric and negative derivative epicardial ventricular electrical activation pattern

From precordial ECG leads, the conventional determination of the negative derivative of the QRS complex (ND-ECG) assesses epicardial activation. Recently we showed that ultra-high-frequency electrocardiography (UHF-ECG) determines the activation of a larger volume of the ventricular wall. We aimed to combine these two methods to investigate the potential of volumetric and epicardial ventricular activation assessment and thereby determine the transmural activation sequence. We retrospectively analyzed 390 ECG records divided into three groups-healthy subjects with normal ECG, left bundle branch block (LBBB), and right bundle branch block (RBBB) patients. Then we created UHF-ECG and ND-ECG-derived depolarization maps and computed interventricular electrical dyssynchrony. Characteristic spatio-temporal differences were found between the volumetric UHF-ECG activation patterns and epicardial ND-ECG in the Normal, LBBB, and RBBB groups, despite the overall high correlations between both methods. Interventricular electrical dyssynchrony values assessed by the ND-ECG were consistently larger than values computed by the UHF-ECG method. Noninvasively obtained UHF-ECG and ND-ECG analyses describe different ventricular dyssynchrony and the general course of ventricular depolarization. Combining both methods based on standard 12-lead ECG electrode positions allows for a more detailed analysis of volumetric and epicardial ventricular electrical activation, including the assessment of the depolarization wave direction propagation in ventricles.

Clinical, electrical, and functional changes following CRT-P implantation: short-term results in patients with non-ischaemic cardiomyopathy

Aim. Assessment of the correlation between cardiac remodeling, functional status and electrical remodeling after cardiac resynchronisation therapy (CRT) in patients with non-ischaemic cardiomyopathy.Material and methods. A single center, prospective, observational study included 50 patients with non-ischaemic cardiomyopathy who were candidate for CRT implantation. All patients prior to CRT and then 3 months after implantation had standard 12-lead surface ECGs to assess QRSd for assessment electrical response, for assessment of left ventricular ejection fraction (LVEF) and volumes (left ventricular end diastolic and systolic volume, LVEDV and LVESV), mitral regurgitation (degree of mitral regurgitation), pulmonary artery systolic pressure (for diagnosis of pulmonary hypertension), NYHA class and 6 minute walk test (6MWT) to assess patient’s functional capacity.Results. 50 patients with CRT were included (35 males and 15 females, mean age 54.88±7.48 years). All patients were in sinus rhythm with QRS duration (QRSd) ≥120 ms, EF&lt;35% and left bundle branch block. After 3 months; there was significant improvement in QRSd in 82% of the cases (145.3±16.3 ms vs 133.3±17.2 ms, p&lt;0.001). NYHA class improved at least one class in 78% and 6 min walk test improved in 80% (168.5 [131.0; 181.0] m vs 280.0 [237.0; 297.0] m, p&lt;0.001). LVEF increased significantly in 74% of study cases (28.6±2.7 vs 34.5±3.1, p value 0.001) also there were statistically significant improvement in LVEDV (267.0±45.7 to 221.8±41.9 ml, p=0.002) and LVESV (137.43±47.19 to 105.03±42.7 ml, p=0.003). There was statistically significant correlation between QRSd and NYHA class (r=0.392, p=0.005), QRSd and 6MWT (r=0.323, p=0.022) and QRSd with LVEF (r=0.672 with p&lt;0.001). Only seven patients showed improvement in the 3 parameters: LVESV, QRS duration and 6 min walk test.Conclusion. The CRT-pacemaker implantation was associated with significant improvement in QRSd, NYHA class, 6MWT and LV volumes in the short-term period. QRSd improvement was significantly correlated with functional status and LV EF.