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The relationship between structural and electrical remodeling in the heart, particularly after long-standing endurance training, remains unclear. Signal-averaged electrocardiogram (SAECG) may provide a more sensitive method to evaluate cardiac remodeling than a 12-lead electrocardiogram (ECG). Accurate measures of electrical function (SAECG filtered QRS duration (fQRSd) and late potentials (LP) and left-ventricular (LV) mass (cardiac magnetic resonance, CMR) can allow an assessment of structural remodeling and QRS prolongation. Endurance athletes (45-65 yr old,10 yr of endurance sport), screened to exclude cardiac disease, had standardized 12-lead ECG, SAECG, resting echocardiogram (ECHO), and CMR performed. SAECG fQRSd was correlated with QRS duration on the 12-lead ECG, and ECHO and CMR-derived LV mass. Participants (

Background Patients with serious mental illness (SMI) have an increased risk of sudden death. Higher rates of signal-averaged electrocardiogram (SAECG) abnormal late potentials (LP), which may be a predictor of sudden death risk, have been shown in patients with schizophrenia. We aimed to assess the prevalence and predictors of electrocardiograph (ECG) and SAECG abnormalities in a mixed SMI population. Methods Consecutive consenting inpatients with SMI had 12-lead ECG and SAECG recorded in addition to demographics, diagnoses and medications. Standard criteria for abnormal SAECG were applied. Multivariate regression analysis was performed to determine predictors of SAECG abnormalities including diagnoses, body mass index, ECG parameters, psychotropic medication use, and medications associated with Long QT or Brugada syndromes. Results Eighty (80) patients, 49% male, mean age 39±17 years were included. SAECG criteria abnormality for 1, 2 or 3 criteria were seen in 19, 3 and 5 cases (34% in total) respectively. Early repolarisation pattern was seen in 19% of patients. SAECG abnormality was associated with male gender (OR 7.3; 95% CI 2.3–23.4), and schizophrenia/schizoaffective disorder diagnosis (OR 7.4; 95% CI 1.9–29.0), but not with medication type or dose. Conclusions In the mixed SMI population studied, there was a high rate of SAECG-detected late potentials (34%) and early repolarisation pattern (19%). Schizophrenia/schizoaffective disorder diagnosis was the strongest multivariate predictor identified. Further studies are needed to define the mechanism and significance of these cardiac abnormalities in SMI patients.

Background Although some post myocardial infarction (post‐MI) and dilated cardiomyopathy (DCM) patients with mid‐range ejection fraction heart failure (HFmrEF/40%‐49%) face an increased risk for arrhythmic sudden cardiac death (SCD), current guidelines do not recommend an implantable cardiac defibrilator (ICD). We risk stratified hospitalized HFmrEF patients for SCD with a combined non‐invasive risk factors (NIRFs) guiding to programmed ventricular stimulation (PVS) two‐step approach. Methods Forty‐eight patients (male = 83%, age = 64 ± 14 years, LVEF = 45 ± 5%, CAD = 69%, DCM = 31%) underwent a NIRFs screening first‐step with electrocardiogram (ECG), SAECG, Echocardiography and 24‐hour ambulatory ECG (AECG). Thirty‐two patients with presence of one of three NIRFs (SAECG ≥ 2 positive criteria for late potentials, ventricular premature beats ≥ 240/24 hours, and non‐sustained ventricular tachycardia [VT] episode ≥ 1/24 hours) were further investigated with PVS. Patients were classified as either low risk (Group 1, n = 16, NIRFs−), moderate risk (Group 2, n = 18, NIRFs+/PVS−), and high risk (Group 3, n = 14, NIRFs+/PVS+). All in Group 3 received an ICD. Results After 41 ± 18 months, 9 of 48 patients, experienced the major arrhythmic event (MAE) endpoint (clinical VT/fibrillation = 3, appropriate ICD activation = 6). The endpoint occurred more frequently in Group 3 (7/14, 50%) than in Groups 1 and 2 (2/34, 5.8%). Logistic regression model adjusted for PVS, age, and LVEF revealed that PVS was an independent MAE predictor (OR: 21.152, 95% CI: 2.618‐170.887, P = .004). Kaplan‐Meier curves diverged significantly (log rank, P, We applied a combined non‐invasive risk factors (NIRFs) leading to programmed ventricular stimulation (PVS), a two‐step risk stratification algorithm, to detect the HFmrEF/40‐49% patients at risk for major arrhythmic events.This combined two‐step approach efficiently detected the patients at increased arrhythmic risk.

Background The majority of beta thalassemia major (β‐TM) patients suffer from cardiac disease, while a significant proportion of them die suddenly. Twelve‐lead and signal‐averaged electrocardiography (SAECG) are simple, inexpensive, readily available tools for identifying an unfavorable arrhythmiological substrate by detecting the presence of arrhythmias, conduction abnormalities, and late potentials (LPs) in these patients. Methods A total of 47 β‐TM patients and 30 healthy controls were submitted to 12‐lead and signal‐averaged electrocardiography. Basic electrocardiographic parameters and prevalence of LPs were recorded. Basic echocardiographic parameters were estimated by transthoracic echocardiography. T2* was calculated by cardiac magnetic resonance imaging wherever available. Results β‐TM patients demonstrated a more prolonged PR interval (167.74 msec vs 147.07 msec) (P = .043), a higher prevalence of PR prolongation (21.05% vs 0%) (P = .013), and a higher prevalence of LPs (18/47, 38.3% vs 2/30, 6.7%) (P = .002) compared with controls. The prevalence of atrial fibrillation among b‐TM patients was estimated at 10.64%. Patients had also greater E/e′ ratio (8.35, SD = 2.2 vs 7, SD = 2.07) (P = .012) and LAVI (30.7 mL/m2, SD = 8.76 vs 24.6 mL/m2, SD = 6.57) (P = .002) than controls. Regression analysis showed that QTc and LAVI could correctly predict the presence of LPs in the 80.9% of the patients. Conclusions β‐TM patients have a higher prevalence of a prolonged PR interval, atrial fibrillation, and LPs. Twelve‐lead and SAECG performance was feasible in all subjects and constitutes a readily available tool for assessing myocardial electrophysiological alterations in this patient group., A cross‐sectional study considering the value of conventional and signal‐averaged electrocardiography in assessment of the arrhythmiological substrate of β‐thalassemia patients.

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Pharmacologic and non-pharmacologic rhythm control strategies impact on AF-related symptoms, while leaving largely unaffected the risk of stroke. Moreover, up to 20% of AF patients are asymptomatic during paroxysmal relapses of arrhythmia, thus underlying the need for early markers to identify at-risk patients and prevent cerebrovascular accidents. Indeed, non-invasive assessment of pre-clinical substrate changes that predispose to AF could provide early identification of at-risk patients and allow for tailored care paths. ECG-derived P wave analysis is a simple-to-use and inexpensive tool that has been successfully employed to detect AF-associated structural and functional atrial changes. Beyond standard electrocardiographic techniques, high resolution signal averaged electrocardiography (SAECG), by recording microvolt amplitude atrial signals, allows more accurate analysis of the P wave and possibly AF risk stratification. This review focuses on the evidence that support P wave analysis to assess AF substrates, predict arrhythmia relapses and guide rhythm-control interventions.

Aims Arrhythmogenic right ventricular cardiomyopathy (ARVC) is diagnosed by a complex set of clinical tests as per 2010 Task Force Criteria (TFC). Avoiding misdiagnosis is crucial to prevent sudden cardiac death as well as unnecessary implantable cardioverter-defibrillator implantations. This study aims to validate the overall performance of the TFC in a real-world cohort of patients referred for ARVC evaluation. Methods and results We included patients consecutively referred to our centres for ARVC evaluation. Patients were diagnosed by consensus of three independent clinical experts. Using this as a reference standard, diagnostic performance was measured for each individual criterion as well as the overall TFC classification. Of 407 evaluated patients (age 38 ± 17 years, 51% male), the expert panel diagnosed 66 (16%) with ARVC. The clinically observed TFC was false negative in 7/66 (11%) patients and false positive in 10/69 (14%) patients. Idiopathic outflow tract ventricular tachycardia was the most common alternative diagnosis. While the TFC performed well overall (sensitivity and specificity 92%), signal-averaged electrocardiogram (SAECG, P = 0.43), and several family history criteria (P ≥ 0.17) failed to discriminate. Eliminating these criteria reduced false positives without increasing false negatives (net reclassification improvement 4.3%, P = 0.019). Furthermore, all ARVC patients met at least one electrocardiogram (ECG) or arrhythmia criterion (sensitivity 100%). Conclusion The TFC perform well but are complex and can lead to misdiagnosis. Simplification by eliminating SAECG and several family history criteria improves diagnostic accuracy. Arrhythmogenic right ventricular cardiomyopathy can be ruled out using ECG and arrhythmia criteria alone, hence these tests may serve as a first-line screening strategy among at-risk individuals.

Signal-averaged electrocardiography (SAECG) has been known to be useful for prediction of lethal ventricular arrhythmias (VA). However, this technique has limitations in patients with intraventricular conduction disturbance (IVCD), which is common in cardiac sarcoidosis (CS). Meanwhile, wavelet-transformed ECG (WTECG) has been reported to be useful for detecting arrhythmogenic substrate hidden within QRS complex. The objective of this study was to assess the utility of WTECG for detecting arrhythmogenic substrate in patients with CS. Forty-four CS patients including 18 patients with VA were retrospectively investigated. The parameters on the signal-averaged electrocardiography (SAECG) and the power of frequency components on WTECG were compared between VA group and non-VA group. Eighteen patients have VA (VT: n = 17, VF: n = 1). LP were detected in 17 in VA group and 24 in non-VA group. WTECG showed that high-frequency components (HFC; 80-150 Hz) were developed in VA group. Peak power value at 150 Hz (P150) was significantly higher in VA group than that in non-VA group (442.9 ± 160.2 vs 316.7 ± 100.8, p = 0.006). The receiver operating characteristic (ROC) curve analysis showed an optimal cutoff point of 336 of P150 for detecting patients with VA, with 82.4% sensitivity, 61.5% specificity, and area under the curve of 0.74 (95% confidence interval [CI] 0.59-0.89). WTECG may be useful for detecting CS patients who are prone to VA.

Purpose Signal-averaged ECG (SAECG) can detect inhomogeneous myocardial conduction in patients presenting with ventricular tachycardia (VT) after myocardial infarction. Radiofrequency ablation (RFCA) aims at elimination of the endocardial late potentials and non-inducibility of VT. Previously, we demonstrated that abnormal SAECG at baseline can return to normal after a successful VT ablation. The present research investigates the post-ablation changes in SAECG after RFCA of VT and their relation to the procedural long-term outcomes. Methods Thirty-three patients (31 male; age 68 ± 9 years; EF 36 ± 12%) with ischemic VT were prospectively enrolled to receive RFCA. One VT (range 1–7) per patient was ablated using substrate-guided RFCA and complete success was achieved in 28 (85%) cases. SAECG was performed before (t1), immediately after (t2), and at least 6 months (t3) after the RFCA. Results After RFCA, the amount of patients showing abnormal SAECG decreased from 82% initially (t1) to 57.6% post-interventionally (t2); P = 0.008; and remained unchanged thereafter in 57% (t3). Patients who experienced VT recurrence (VT+) during the follow-up period had broader averaged QRS (t2): (VT+) 150 ± 26 vs. (VT−) 129 ± 21 ms; P = 0.015, as well as longer LAS40 (t2): (VT+) 60 ± 26 vs. (VT−) 43 ± 18 ms; P = 0.03. Abnormal SAECG (t2) was a strong predictor for VT recurrence: HR 5.4; 95% CI 1.5–21. SAECG detected more late potentials in patients with inferior than in those with anterior scars: 95% vs. 58%; P = 0.016. Conclusions RFCA of VT in the left ventricle can improve an abnormal SAECG in some patients after myocardial infarction. Normal SAECG after RFCA of VT is associated with a lower risk for VT recurrence and death.

The known mechanisms for cardiac arrhythmias are disorders of impulse formation, disorders of impulse conduction, or combinations of both. However, in many cases, a combination of mechanisms is responsible for arrhythmia initiation or perpetuation. Sometimes arrhythmia caused by one mechanism could initiate another arrhythmia, such as one PAC with an automaticity mechanism could initiate a macroreentrant atrial tachycardia. The risk of different types of arrhythmia is various; some of them such as VF are very hazardous. AF may be sometimes silent and sometimes cause CVA. There are different diagnostic approaches for diagnosis of arrhythmia, such as ECG, Holter monitoring, SAECG, and invasive electrophysiologic study (EPS). Therapy for cardiac arrhythmia includes antiarrhythmic drugs, electrical cardioversion, radiofrequency ablation of the source of the arrhythmia (RFA), freezing of the culprit site of the arrhythmia, and surgical ablation.

BACKGROUND: Late potentials (LPs) identified on the signal averaged electrocardiogram (SAECG) are a marker for an increased risk of arrhythmias in Brugada syndrome (BrS). Procainamide is a sodium channel blocker used to diagnose BrS. The effects of Procainamide on the SAECG in those with BrS and the significance of Procainamide-induced LPs are unknown.METHODS: Procainamide provocation was performed for suspected BrS with 12-lead and SAECG pre- and post-infusion. Filtered QRS duration (fQRSd), duration of low amplitude signals RESULTS: Data from 150 patients were included in the analysis (mean age 44.5 years, 109 males). Procainamide increased fQRSd (Pre 118.8 ± 10.5 ms, post 121.2 ± 10.2 ms, p < 0.001) and LAS40 (Pre 38.7 ± 9.8 ms, post 40.2 ± 10.5 ms, p = 0.005) and decreased RMS40 (Pre 24.6 ± 12 ms, post 22.8 ± 12 ms, p = 0.002). LPs were present in 68/150 (45%) at baseline. Fifteen patients with negative baseline SAECGs had LPs unmasked by Procainamide, but six patients had LPs at baseline that were no longer present following Procainamide. Comparing those with normal hearts (n = 48) to those with a final diagnosis of BrS (n = 38), Procainamide prolonged fQRSd to a greater extent in those with BrS. Comparing those with Procainamide-induced LPs to those with no LPs at any time did not highlight any aspect of phenotype and did not correlate with a history of ventricular arrhythmias.CONCLUSIONS: Procainamide influences the SAECG, provoking LPs in a small proportion of patients. However, there is no evidence that Procainamide-induced LPs provide additional diagnostic information or aid risk stratification.

Introduction Brugada syndrome (BS) is a relevant cause of sudden death in individuals without structural heart disease. The accuracy of the available methods for risk stratification is very limited and the investigation of new methodologies to improve the identification of patients at risk is under intensive investigation. Recently the pathophysiological relevance of anomalous, fragmented and prolonged electrograms on the epicardial surface of the right ventricular outflow tract (RVOT) has been described. Therefore, the study of signal-averaged ECG (SA-ECG) has become attractive since it may allow the non-invasive evaluation of these electrical anomalies. In order to maximize the detection capacity and to focus the evaluation in the RVOT, we developed an alternative methodology of electrode positioning directed to this area of interest. Purpose To characterize the study of late potentials (LP) by SA-ECG in patients with SB and to evaluate its association with the occurrence of arrhythmia events. Methods Prospective single centre study of patients (pts) with BS. LP were evaluated by SA-ECG with determination of the total filtered QRS duration (fQRS), root mean square voltage of the 40 ms terminal portion of the QRS (RMS40) and duration of the low amplitude electric potential component (40 microV) of the terminal portion of the QRS (LAS40) in conventional and modified leads (addressed to RVOT). The association of LP with the risk of definite malignant dysrhythmias due to sudden death, ventricular fibrillation, ventricular tachycardia or appropriate shock of the implantable cardioverter defibrillator (ICD) was evaluated and the acuity of the prognostic stratification was determined by the area under the receiver operator characteristic curve (ROC). Results A total of 76 pts (69.7% men, age 48±12 years) were studied, of which 33 had a spontaneous type 1 pattern and 43 had a type 1 pattern induced by flecainide. During a median follow-up of 1.6 years, 13 pts (17.1%) had symptoms potentially related to BS and 6 (10.5%) had malignant arrhythmias [including two pts who suffered sudden death (2.6%). The pts who had malignant dysrhythmias presented higher values of fQRS (125±23 vs. 108±18, p=0.046) and LAS40 (54±13 vs. 40±11, p=0.014), and lower values of RMS40 only in the modified leads (11±5 vs. 22±19, p=0.041). The parameters of the SA-ECG were significant prognostic predictors. The acuity of each of the parameteres alone was moderate and the parameters that were identified as more powerful predictors of risk were those derived from the modified leads (Figure). Conclusion The LP evaluated by SA-ECG may be relevant in the prognostic stratification of patients with BS, since it seems to be associated with the risk of malignant ventricular arrhythmias. Funding Acknowledgement Type of funding sources: None.

Introduction: Postoperative atrial fibrillation (POAF) is common after cardiac surgery and associated with increased hospital length of stay, patient morbidity and mortality. We aimed to identify factors associated with POAF and evaluate the accuracy of available POAF prediction models. Methods: We screened articles from Ovid MEDLINE® and PubMed Central® (PMC) and included studies that evaluated risk factors associated with POAF or studies that designed or validated POAF prediction models. We only included studies in cardiac surgical patients with sample size n ⩾ 50 and a POAF outcome group ⩾20. We summarised factors that were associated with POAF and assessed prediction model performance by reviewing reported calibration and discriminative ability. Results: We reviewed 232 studies. Of these, 142 fulfilled the inclusion criteria. Age was frequently found to be associated with POAF, while most other variables showed contradictory findings, or were assessed in few studies. Overall, 15 studies specifically developed and/or validated 12 prediction models. Of these, all showed poor discrimination or absent calibration in predicting POAF in externally validated cohorts. Conclusions: Except for age, reporting of factors associated with POAF is inconsistent and often contradictory. Prediction models have low discrimination, missing calibration statistics, are at risk of bias and show limited clinical applicability. This suggests the need for studies that prospectively collect AF relevant data in large cohorts and then proceed to validate findings in external data sets.

Considering the importance of ventricular arrhythmias in the prediction of sudden cardiac death in chronic Chagas heart disease, the aim of the present study was to associate late potentials observed in the signal-averaged electrocardiogram (SAECG) with either non-sustained ventricular tachycardia in the 24-hour Holter monitoring or reduced left ventricular ejection fraction in the 2-dimension echocardiogram.This was a retrospective transversal study. The medical charts of 49 patients with chronic Chagas heart disease that underwent 24-hour Holter monitoring at our institution from September 2012 to December 2015 were reviewed. In the univariate analysis, variables associated with SAECG at a p value0.05 were entered a multivariate stepwise logistic regression analysis through the model forward. A p value0.05 was considered to have statistical significance.In the univariate analysis, right bundle branch block, left atrial diameter, left ventricular systolic diameter, and left ventricular ejection fraction were associated with late potential in the SAECG. In the multivariate analysis, however, right bundle branch block and left atrial diameter were retained as independent predictors of late potentials in the SAECG.Neither ventricular arrhythmias in the 24-Holter monitoring nor reduced left ventricular ejection fraction in the 2-D echocardiogram were associated with late potentials in the SAECG of patients with chronic Chagas heart disease.

Atrial arrhythmias occur at a higher than expected prevalence amongst endurance athletes. Few studies have examined both atrial structure and arrhythmias in middle-aged endurance athletes. We examined the relationship between P-wave duration, atrial dimensions, and the presence of atrial ectopy in long-standing, middle-aged endurance athletes.Middle-aged athletes with a minimum of 10 years of competitive endurance sport history and no history of structural heart disease or clinical atrial arrhythmias, had 12-lead ECGs to assess P-wave duration, signal-averaged ECGs (SAECG) to assess filtered P-wave duration, a 24 h Holter monitor to assess atrial ectopy, and echocardiography and cardiac magnetic resonance imaging to assess atrial structural characteristics.Amongst endurance athletes (n = 104; mean age = 54 ± 5 years; 63% male), filtered P-wave duration on SAECG was correlated with P-wave duration on 12-lead ECG (r = 0.36, p, 0.0001), as well as with larger CMR-derived RA areas (r = 0.30, p = 0.01) and volumes (r = 0.24, p 0.05). There was no correlation between filtered P-wave duration and any LA measures on imaging (p 0.05). There was no correlation between the incidence of atrial ectopy (premature atrial contractions or atrial tachycardia) and any electrocardiographic or structural measures.Longer filtered P-wave duration was associated with larger RA areas and volumes, without an increase in atrial ectopy.

Introduction Several noninvasive risk factors for ventricular arrhythmias have been described in postmyocardial infarction (MI) patients, whose relationships with scar characteristics and modifications by ablation are unknown. Methods Twenty-two patients with previous MI referred for ventricular tachycardia ablation were prospectively included. ECG, heart rate variability (HRV), signal-averaged ECG (SA-ECG), and T wave alternans (TWA) were performed before and after radiofrequency ablation. Scar areas were correlated to preablation parameters. Pre and postablation parameters were furthermore compared. Results Left ventricular ejection fraction and some spectral and time-domain HRV parameters were significantly correlated to the scar areas. QRS duration was larger after vs before ablation (120 ± 29 vs 105 ± 22 msec, P = .01). No significant modification in time or spectral domain of HRV was observed. There was no significant change in TWA and SA-ECG before and after ablation. Borderline decreases in quantitative TWA parameters were noted in patients with positive TWA and successful ablation procedure. Conclusion Some noninvasive risk factors were linked to the scar areas, but few were significantly modified after ablation. Larger populations are needed to demonstrate significant differences or correlations.

Introduction While cardiac sarcoidosis (CS) carries a risk of ventricular arrhythmias (VAs) and sudden cardiac death (SCD), risk stratification of patients with CS and preserved left ventricular/right ventricular (LV/RV) systolic function remains challenging. We sought to evaluate the role of electrophysiologic testing and programmed electrical stimulation of the ventricle (EPS) in patients with suspected CS with preserved ventricular function. Methods One hundred twenty consecutive patients with biopsy-proven extracardiac sarcoidosis and preserved LV/RV systolic function underwent EPS. All patients had either probable CS defined by an abnormal cardiac positron emission tomography or cardiac magnetic resonance imaging, or possible CS with normal advanced imaging but abnormal echocardiogram (ECG), SAECG, Holter, or clinical factors. Patients were followed for 4.5 ± 2.6 years for SCD and VAs. Results Seven of 120 patients (6%) had inducible ventricular tachycardia (VT) with EPS and received an implantable cardioverter defibrillator (ICD). Three patients (43%) with positive EPS later had ICD therapies for VAs. Kaplan-Meier analysis stratified by EPS demonstrated a significant difference in freedom from VAs and SCD (P = 0.009), though this finding was driven entirely by patients within the cohort with probable CS (P = 0.018, n = 69). One patient with possible CS and negative EPS had unrecognized progression of the disease and unexplained death with evidence of CS at autopsy. Conclusions EPS is useful in the risk stratification of patients with probable CS with preserved LV and RV function. A positive EPS was associated with VAs. While a negative EPS appeared to confer low risk, close follow-up is needed as EPS cannot predict fatal VAs related to new cardiac involvement or disease progression.

Experimental and clinical studies have shown that after myocardial infarction (MI), increases the risk to develop cardiac arrhythmias. We have evaluated the ventricular activation during healing (MI7) and healed (MI60) stages after MI. We carried out a comparative study between the QRS spectral variance (QRSSV) index and late potentials (LPs) obtained by the Signal-averaged (SaECG) technique. The electrocardiograms of 48 healthy subjects (CTRL); 84 patients in MI7 and 41 in MI60 without VT/VF; and also 7 patients in MI7 and 6 in MI60 with VT/VF, were analysed utilizing the Frank leads. The QRSSV has increased (p < 0.05) in patients without VT/VF for all leads during MI7 and MI60 with respect to CTRL, and just in a few leads in patients with VT/VF. Conversely, we have only found significant proportion of LPs in MI7 with respect to CTRL in patients with VT/VF and none without VT/VF. This investigation might help to comprehend the influence of time in patients with and without VT/VF. We conclude that SaECG could be restricted to locate stable and delayed depolarization, while the QRSSV index could detect both stable and unstable activation disorders in whole depolarization. Fil: Valverde, Esteban Raul. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Ingeniería Biomédica; Argentina Fil: Arini, Pedro David. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Ingeniería Biomédica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina

Introduction A spontaneous type I electrocardiogram (ECG) pattern and/or unheralded syncope are conventionally used as risk markers for primary prevention of sudden cardiac arrest/death (SCA/SCD) in Brugada syndrome (BrS). In this study, we determine the prevalence of conventional and newer markers of risk in those with and without previous aborted SCA events. Methods All patients with BrS were identified at our institute. History of symptoms was obtained from medical tests or from interviews. Other markers of risk were also obtained, such as presence of (1) spontaneous type I pattern, (2) fractionated QRS (fQRS), (3) early repolarization (ER) pattern, (4) late potentials on signal‐averaged ECG (SAECG), and (5) response to programmed electrical stimulation. Results In 133 patients with Bars, 10 (7%) patients (mean age = 39 ± 11 years; nine males) were identified with a previous ventricular fibrillation/ventricular tachycardia episode (n = 8) or requiring cardio‐pulmonary resuscitation (n = 2). None of these patients had a prior history of syncope before their SCA event. Only two (20%) patients reported a history of palpitations or dizziness. None had apneic breathing and three (30%) patients had a family history of SCA. From their ECGs, a spontaneous pattern was only found in one (10%) of these patients. Further, 10% of patients had fQRS, 17% had late potentials on SAECG, 20% had deep S waves in lead I, and 10% had an ER pattern in the peripheral leads. No significant differences were observed in the non‐SCA group. Conclusion The majority of BrS patients with previous aborted SCA events did not have a spontaneous type I and/or prior history of syncope. Conventional and newer markers of risk appear to only have limited ability to predict SCA.

Funding Acknowledgements Type of funding sources: None. Introduction The 2010 Task Force Criteria (TFC) for the diagnosis of arrhythmogenic right ventricular cardiomyopathy (A(R)VC) in 1st degree relatives includes an abnormality in a single parameter of the signal averaged ECG (SAECG). SAECG normal ranges were derived predominately from ischaemic heart disease patients, so may not be applicable in an A(R)VC population. There remain concerns that the SAECG is not specific enough and its role in the diagnosis of A(R)VC is under scrutiny. Purpose to improve the diagnostic utility of the SAECG Methods Patients with an A(R)VC diagnosis and 1st degree family members (FM) under follow-up at a single inherited cardiac conditions (ICC) centre were included. All cases were independently reviewed by 3 cardiologists experienced in the diagnosis and management of A(R)VC. All SAECGs included were free from artefact. TFC clinical variables and genetic status were recorded for each patient. Where tests had been repeated the most recent values were used. Because of concerns about the use of a single abnormal SAECG parameter in making a clinical diagnosis we required ≥2 abnormal SAECG parameters, or a confirmed genetic mutation to make a diagnosis. A diagnosis of false positive SAECG was made with ≥2 abnormalities when the individual was known not to carry the familial pathogenic mutation. Results A study population of 160 patients (male 103 (64%), age 46yrs (range 18-85yrs); 41 pro-bands and 119 FM. 62(52%) FM had a clinical diagnosis of AVC, with ARVC the pre-dominant phenotype 51(82%). A pathogenic genetic variant was identified in 24(47%) of FM with ARVC. The SAECG data is presented graphically for each parameter. A clinical diagnosis of ARVC was made on the basis of an affected 1st degree FM and an abnormal SAECG in 24(47%) of FM. Of these, 16(67%) had three abnormal SAECG parameters, 6(25%) two and 2(8%) a single abnormal parameter. Both patients with only one abnormal SAECG parameter carry a pathogenic variant. In total 88% of FM with ARVC, and 32% of FM without AVC had an abnormal SAECG as per current TFC. False positive values were mainly in fQRS duration (17/18), but also LAS40 (5/18), and RMS40 (2/18). By redefining an abnormal fQRS duration to be ≥118ms, false positives are reduced from 17 to 4. In addition, if there is a requirement for a 2nd abnormality then the false positives are reduced to 2 (4%). By adjusting the diagnostic criteria to fQRS duration ≥118ms, with a 2nd abnormal parameter or known pathogenic gene carrier status none of the 24 FM with a clinical diagnosis on abnormal SAECG alone would change diagnostic classification. Conclusion The SAECG is useful in family screening as it is frequently the only test to show an abnormality. However, the current TFC reference values lack specificity. By redefining an abnormal fQRS as ≥118ms with the requirement of a 2nd abnormal parameter, specificity is increased to 96%, with no significant change in sensitivity. Abstract Figure. SAECG Parameters in Family Members

Background and objectives Athlete’s heart is characterized by structural cardiac changes, including enlargement and hypertrophy. However, exercise-induced cardiac electrical remodeling is not well known in Asian athletes. We sought to evaluate the association between vigorous exercise and the development of abnormal late potential on signal-averaged electrocardiogram (SAECG). Method We analyzed 48 Korean professional soccer players and 71 healthy sedentary controls who underwent SAECG and transthoracic echocardiography at Kyung Hee University Hospital. An SAECG was considered abnormal (positive for ventricular late potential) when any one of the three following criteria was met: filtered QRS duration > 114 ms, root-mean-square voltage in the terminal 40 ms Results Fragmented QRS was more commonly found in athletes (1.4% vs. 10.4%). Athletes demonstrated significantly higher proportion of filtered QRS duration > 114 ms (7.0% vs. 22.9%, P = 0.013) and lower terminal QRS root-mean-square voltage P = 0.012). Ventricular late potential on SAECG was significantly more frequent in athletes (15.5% vs. 35.4%, P = 0.012). Regarding echocardiographic parameters, the athletes had larger cardiac chamber size; however, these differences became non-significant after adjustment for body surface area, except left ventricular mass index (65.7 ± 12.7 g/m2 vs. 84.7 ± 17.7 g/m2, P Conclusion Abnormal SAECG findings were significantly more common in athletes than in controls. Further study is needed to determine the clinical impact of these abnormal SAECGs in athletes and cardiac outcomes in the long term.

Introduction The clinical utility of inferolateral early repolarisation (ER) and late potentials (LP) in children with Brugada Syndrome (BrS) has not been previously evaluated. The aim of this study was to determine the prevalence of electrocardiographic (ECG) abnormalities in children with BrS, and to investigate their relationship with clinical outcomes. Methods 43 patients with BrS and 47 controls aged ≤18 undergoing systematic clinical and ECG evaluation, including signal-averaged ECG (SAECG) and pharmacological provocation testing, between 2003 and 2019 were included. Results Four patients with BrS (9%) presented with a spontaneous type 1 Brugada pattern; the remaining 39 (91%) were diagnosed following ajmaline provocation testing. Twelve BrS patients (28%) had late potentials (LP) on SAECG compared to 1 (2%) in controls (p = 0.001). LP were more common in 5 patients with a high-risk phenotype (60% vs 24%) but this was not statistically significant. Twelve patients with BrS (28%) had inferolateral early repolarisation (ER) and 2 (5%) had fractionated QRS (f-QRS), but there were no statistically-significant differences with controls in these parameters. A significant arrhythmia (non-sustained ventricular tachycardia or atrial fibrillation) was seen in 4 patients (9%). Conclusions This study shows a high prevalence of SAECG abnormalities in children with BrS compared with controls, but this was not significantly associated with a high-risk phenotype.

Background Early detection of cardiac involvement in patients with sarcoidosis is important but currently unresolved. The aim of this study was to elucidate the utility of frequency domain microvolt T‐wave alternans (TWA), signal‐averaged ECG (SAECG), and heart rate turbulence (HRT) using 24‐hour Holter ECG for detecting cardiac involvement in patients with pulmonary sarcoidosis. Methods This study consisted of consecutive 40 pulmonary sarcoidosis patients (11 males, 62 ± 13 years) who underwent 24‐hour Holter monitoring with and without cardiac involvement. All patients underwent frequency domain TWA, SAECG, and HRT using 24‐hour Holter monitoring. Patients with atrial fibrillation pacing or wide QRS electrocardiogram were excluded. Results After 14 patients were excluded, a total of 26 patients (six males, 59 ± 14 years) were evaluated. Seven patients had cardiac involvement (cardiac sarcoidosis [CS] group). On the Holter SAECG, duration of low‐amplitude signals, Holter‐based signal‐averaged ECG showed high prevalence of positive late potentials (LP) in cardiac sarcoidosis (CS) patients.

Background The peri‐outflow tract region could be the origin of ventricular tachycardia (VT) after aortic valve replacement (AVR). However, the clinical characteristics of outflow tract ventricular tachycardias (OTVTs) after AVR are yet to be clarified. This study investigated the incidence, risk factors, and clinical characteristics of patients with OTVTs after AVR. Methods We retrospectively analyzed the clinical course of 120 patients who had undergone surgical AVR (SAVR) between April 1980 and October 2018. The patients had no ischemic or diagnosed cardiomyopathies other than primary aortic valve diseases. Results Six patients (5.0%) developed OTVTs after SAVR. The average onset was at 10.8 ± 5.7 years after SAVR. All cases of VT arose from the inferior axis and included left and right bundle branch block configuration. Two patients who underwent cardiac magnetic resonance imaging (MRI) had late gadolinium enhancement (LGE) in the midlayer of the left ventricle basal anteroseptal wall. Patients with periaortic VTs had significantly larger left ventricular (LV) diameter at systole, lower LV ejection fraction, higher positive rates of signal‐averaged electrocardiogram (SAECG), and nonsustained VTs on Holter monitoring. On ablation, local fragmented potentials with low voltage zones were observed in accordance with the LGE distribution. Multiple VTs originating from the periaortic region were provoked in the sessions. Conclusions Acute OTVT was found in 5% of patients after SAVR. Arrhythmia risk stratification by SAECG, Holter ECG, and cardiac MRI should be considered for a long period in patients after SAVR., Based on our results, acute onset of OTVT was found in 5% of patients who received SAVR. Therefore, we suggest that arrhythmic risk stratification should be considered for patients who have undergone SAVR for a long period.

Objective: To investigate the incidence, risk factors and clinical characteristics of periaortic VTs after AVR. Background: The periaortic region is the origin of some ventricular tachycardias (VTs) after aortic valve replacement (AVR). However, the clinical characteristics of periaortic VTs after AVR are yet to be clarified. Methods: We retrospectively analyzed clinical courses of 109 patients who had undergone surgical AVR (SAVR) without other structural heart diseases between April 2009 and Jun 2019 and evaluated the incidence and characteristics of periaortic VTs after SAVR. Results: Three patients (2.8%) developed periaortic VTs after SAVR. The average duration of onset was 12.3±6.6 years. All VTs arose from the inferior axis; they included both left and right bundle branch block configuration (LBBB and RBBB). Two patients underwent cardiac magnetic resonance imaging; late gadolinium enhancement (LGE) was observed in the mid-layer of the left ventricle basal anteroseptal wall in both cases. Patients with periaortic VTs had significantly wider interventricular septum, lower left ventricular ejection fraction (LVEF), larger LV diameter at systole, and higher positive rates of signal-averaged ECG and non-sustained VTs on Holter. On ablation, local fragmented potentials with low voltage zones were observed in accordance with the distribution of LGE. Multiple VTs originating from the periaortic region were provoked in the sessions. Conclusions: Periaortic VTs long after surgical AVR are not rare, and arrhythmia risk stratification, including that by signal averaged electrocardiogram (SAECG), Holter, and cardiac magnetic resonance imaging (MRI) should be considered.

Introduction The sudden cardiac death risk in Brugada Syndrome (BrS) is higher in patients with spontaneous type 1 pattern. Brugada diagnosis is also established in patients with induced type 1 morphology after provocative test with intravenous administration with a sodium blocker channel. Nevertheless, this group of patients is known to be at a lower risk of SCD, and their risk stratification is still a matter of discussion. Late potentials (LP) detected on signal-averaged ECG (SAECG) on the RVOT have been previously proposed as a predictor factor for BrS, even though data is lacking on its value. Purpose To evaluate the association between positive LP (LMS40> 38ms) on SAECG with modified Brugada leads and a positive flecainide test in patients with non-type 1 BrS. Methods Retrospective single-center study of non-type 1 BrS patients referred for the performance of a flecainide provocative test. Patients presenting with spontaneous type 1 morphology were excluded from the study. Study of LP on SAECG with modified leads for Brugada were evaluated before administration of flecainide [2mg/kg (maximum150mg), for 10minutes] with determination of filtered QRS duration (fQRS), root mean square voltage of the last 40ms of the QRS complex (RMS40) and duration of low amplitude signals Results 126 patients (47.3 ± 14.1 years, 61.9% males) underwent study with LP SAECG and flecainide test. Among these patients, 7.9% were symptomatic and 16.7% had familiar history of BrS. Flecainide test was positive in 46.8% of patients. In patients with a positive flecainide test, 64.4% presented LMS40 > 38ms whereas LMS40 > 38ms was present in only 46% of those with a negative flecainide test (p = 0.031). The presence of positive LMS40 was a positive predictor for a positive flecainide test, associated with a two-fold increase likelihood in the induction of a Brugada pattern (OR: 2,12; IC95% 1,025-4,392; P = 0,043). There was no association between fQRS or RMS40 and a positive flecainide test (p = NS). fQRS > 114ms and RMS40 Conclusion In patient with non-type 1 Brugada syndrome, LMS40 > 38ms in SAECG was a predictor for a positive flecainide test, suggesting that this finding could be helpful on the risk stratification of patients undergoing diagnostic study for Brugada syndrome. Abstract Figure. Effect of LMS 40 in flecainide test

IntroductionSarcoidosis is a multisystem disease, predominantly affecting the lungs but can involve the heart, resulting in cardiac sarcoidosis (CS). Patients require MRI/Positron Emission Tomography (PET) scans for diagnosis. Echocardiography, ECG and Holter monitoring may be indicative but not diagnostic alone. Patients can present late with conduction defects, heart failure or sudden death. The CASPA (CArdiac Sarcoidosis in PApworth) study protocol aims to (1) use MRI to identify CS prevalence; (2) use speckle-tracking echocardiography, signal averaged ECG and Holter monitoring to look for diagnostic pathways; and (3) identify serum proteins which may be associated with CS.Methods and analysisParticipants with pulmonary sarcoidosis (and no known cardiac disease) from Royal Papworth Hospital will have the following: cardiac MRI with late gadolinium, two-dimensional transthoracic echocardiography with speckle tracking, signal averaged ECG and 24-hour Holter monitor. They will provide a serum sample for brain natriuretic peptide levels and proteomics by liquid chromatography coupled to high-resolution mass spectrometry. All data will be collected on OpenClinica platform and analysed approximately 6 months after final patient recruitment.Ethics and disseminationThe Camden & Kings Cross Research Ethics Committee approved the protocol (REC number: 17/LO/0667). Integrated Research Approval System (IRAS) 222 720. Dissemination of findings will be via conference presentations and submitted to peer-reviewed journals.

Although the standard ECG provides substantial information on cardiac electrical activity, it fails to record signals in the microvolt range. Signal averaging technique enables recording and identification of low amplitude signals by improving the signal-to-noise ratio. Thus, the signal-averaged ECG (SAECG) was initially used for noninvasive recording of His bundle potential and subsequently to detect “late potentials” (LPs) for risk assessment for sudden cardiac death (SCD) and/or VT in various clinical settings. However, the initial enthusiasm for the SAECG waned following the results of the MADIT-II Trial that opted the use of ejection fraction (EF) as the main risk stratifying modality. In this chapter, the role of the SAECG in other conditions such as infiltrative heart disease, right ventricular dysplasia, evaluation of syncope, tetralogy of Fallot-associated VT, the Brugada syndrome, post-ablation of VT, and atrial fibrillation is discussed.

Метою дипломної роботи є визначення різниці між пацієнтами з нормальними сигналами електрокардиограми. Для цього необхідно створити норму для групи молодих людей та визначити їх «відстань» до створеної норми. На основі отриманих результатів складені висновки про різницю між клінічно здоровими та схожими пацієнтами. В першому розділі розглянуті теоретичні відомості про історію ЕКГ, методику отримання сигналу ЕКГ, способи отримання усередненого комплексу та можливе їх використання. В другому розділі описується теорія машинного навчання, запропонований метод вирішення поставленого перед роботою завдання. Відповідно запропонованого способу розглянуті доступні алгоритми машинного навчання та обраний найбільш підходящий (Isolation Forest). В третьому розділі описані використовувані вхідні дані. Вони отримані з бази даних курсантів військового училища. Вікова категорія – 17 - 19 років, всі пацієнти вважаються клінічно здоровими. На стадії формування завдання дипломної роботи було прийнято рішення використовувати усереднений кардіокомплекс. В практичній частині створений код для вичитування і форматування вхідних даних з файлів. Використовуючи обраний метод побудована область норми та визначені аномалії відносно неї. Отримані результати порівняні з аналізом програми Cardiol. Всі пацієнти, судячи з результатів програми, мають деякі відхилення в комплексі показників, що відповідають за стан міокарду в різній мірі. Зроблено висновок про поняття норми для різни вікових категорій пацієнтів та запропоновані методи покращення результатів експерименту. The purpose of this thesis is determination the difference between patients with normal ECG signals. Necessary to create a “normal cloud” for a group of young people and determine their “distance” to the established “cloud”. Based on the results obtained, it is possible to draw conclusions about difference between clinically healthy and similar patients. Partially answer the question: “How healthy is the patient?”. In the first section, there are theoretical information about the history of the ECG, method of obtaining an ECG signal, methods of obtaining an averaged ECG complex and their possible using. In the second section there are describes the theory of machine learning, proposed method of increasing main problem of labor. According to the proposed method, the available machine learning algorithms are considered and the most suitable (Isolation Forest) was selected. It is advantages are: 1. The possibility to work with multidimensional input data; 2. Low consumption computer resource; 3. The possibility of automatic formation of a “normal” sample. The third section describes the inputs used. They are obtained from the database of cadets of military school. Age category – 17-19 years, all of patients are clinically healthy. At the stage of forming the thesis task, it was decided to use an averaged cardio complex. In the practical part, code is created for reading and formatting input data from files. The “norm cloud” was constructed and anomalies are defined. The obtained results was comparable with the analysis of the program, that names Cardiol. All patients have some deviations in the set of parameters that are responsible for the state of the myocardium. Interesting, that 36% of them do not belong to a given age category. They are 67% of similar records in the entire database. Based on this fact conclusion – concept of norm for different age categories of patients is differ. The following steps have been proposed to improve the outcomes: 1. Refinement and increase the database; 2. To find the most weighty parameters for used algorithm; 3. More correctly find the parameters.

BACKGROUND QRS abnormalities may not be apparent in sinus rhythm in electrically stable cardiomyopathy patients who can have quiescent but highly arrhythmogenic substrate. Here, we test the hypothesis that differential changes in QRS construction during right-ventricular apex pacing (RVP) as opposed to atrial pacing (AP) will identify latent substrate for ventricular arrhythmias (VA) and death. METHODS Forty patients with cardiomyopathy free of VA underwent baseline 114-electrode body-surface electrocardiogram during AP (100 beats per minute [bpm]) and RVP (100 and 120 bpm). The filtered-averaged QRS at each electrode was deconstructed into individual intra-QRS and post-QRS ventricular myopotentials (VMP ). The primary outcome was VA or death. Prognostic accuracy of VMP was validated using V1 to V6 leads in another prospective cohort of 44-cardiomyopathy patients. RESULTS Twenty-six patients were eligible for initial analysis. After 5 ± 2 years of follow-up, eight (31%) patients had VA (VAPos ) while rest were uneventful (VANeg ). During AP100 , VAPos patients expressed more VMP than VANeg patients (16 ± 1 vs 12 ± 1, P = 0.02). RVP100 and RVP120 in VAPos patients introduced an additional 5.5 ± 0.5 and 6.0 ± 0.5 VMP (P