Electrocardiographic Early Repolarization

Clinical characteristics of electrical storm in patients with early repolarization syndrome

BACKGROUND

Early repolarization syndrome (ERS) is an idiopathic ventricular fibrillation (VF) associated with inferolateral J waves. While electrical storm (ES) in ERS is not rare, their characteristics and risk factors are not fully understood.

OBJECTIVE

This study aimed to clarify the significance of ES in ERS.

METHODS

We evaluated 44 patients with ERS who experienced VF/sudden cardiac death or arrhythmic syncope. We assessed clinical characteristics to identify the risk factors for ES.

RESULTS

In total, 13 patients (30%) experienced ES (ES group). Of these, 11 patients (85%) experienced ES during the acute phase of initial VF episodes and 2 patients (2%) experienced ES during follow-up. VF associated with ES occurred during therapeutic hypothermia in 6 of 13 patients (46%). The J-wave voltage during therapeutic hypothermia was higher in the ES group than that in the patients without ES. Isoproterenol was used in 5 patients (38%), which decreased J-wave voltage and relieved ES. Among the clinical markers, shorter QT and QTp intervals (the interval from QRS onset to the peak of T wave), pilsicainide-induced ST elevation, and high scores on the Shanghai Score System were associated with ES. Although pilsicainide induced ST elevation in 6 of 34 patients (18%), spontaneous Brugada electrocardiographic patterns did not appear to be associated with VF. Therapeutic hypothermia was also a risk factor for acute phase ES.

CONCLUSION

Patients with ERS in the ES group frequently had short QT and QTp intervals, pilsicainide-induced ST elevations, and high Shanghai Score System scores. Therapeutic hypothermia was also associated with acute phase ES.

2024 Heart Disease and Stroke Statistics: A Report of US and Global Data From the American Heart Association

BACKGROUND

The American Heart Association (AHA), in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, nutrition, sleep, and obesity) and health factors (cholesterol, blood pressure, glucose control, and metabolic syndrome) that contribute to cardiovascular health. The AHA Heart Disease and Stroke Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, brain health, complications of pregnancy, kidney disease, congenital heart disease, rhythm disorders, sudden cardiac arrest, subclinical atherosclerosis, coronary heart disease, cardiomyopathy, heart failure, valvular disease, venous thromboembolism, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The AHA, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States and globally to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2024 AHA Statistical Update is the product of a full year's worth of effort in 2023 by dedicated volunteer clinicians and scientists, committed government professionals, and AHA staff members. The AHA strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional global data, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Correction of Ito in human induced pluripotent stem Cell-derived cardiomyocyte carrying DPP6 mutation in early repolarization syndrome by CRISPR/Cas9 genome editing

Early repolarization syndrome (ERS) is defined as occurring in patients with early repolarization pattern who have survived idiopathic ventricular fibrillation with clinical evaluation unrevealing for other explanations. The pathophysiologic basis of the ERS is currently uncertain. The objective of the present study was to examine the electrophysiological mechanism of ERS utilizing induced pluripotent stem cells (iPSCs) and CRISPR/Cas9 genome editing. Whole genome sequencing was used to identify the DPP6 (c.2561T > C/p.L854P) variant in four families with sudden cardiac arrest induced by ERS. Cardiomyocytes were generated from iPSCs from a 14-year-old boy in the four families with ERS and an unrelated healthy control subject. Patch clamp recordings revealed more significant prolongation of the action potential duration (APD) and increased transient outward potassium current (Ito) (103.97 ± 18.73 pA/pF vs 44.36 ± 16.54 pA/pF at +70 mV, P < 0.05) in ERS cardiomyocytes compared with control cardiomyocytes. Of note, the selective correction of the causal variant in iPSC-derived cardiomyocytes using CRISPR/Cas9 gene editing normalized the Ito, whereas prolongation of the APD remained unchanged. ERS cardiomyocytes carrying DPP6 mutation increased Ito and lengthen APD, which maybe lay the electrophysiological foundation of ERS.

Primary Electrical Heart Disease-Principles of Pathophysiology and Genetics

Primary electrical heart diseases, often considered channelopathies, are inherited genetic abnormalities of cardiomyocyte electrical behavior carrying the risk of malignant arrhythmias leading to sudden cardiac death (SCD). Approximately 54% of sudden, unexpected deaths in individuals under the age of 35 do not exhibit signs of structural heart disease during autopsy, suggesting the potential significance of channelopathies in this group of age. Channelopathies constitute a highly heterogenous group comprising various diseases such as long QT syndrome (LQTS), short QT syndrome (SQTS), idiopathic ventricular fibrillation (IVF), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and early repolarization syndromes (ERS). Although new advances in the diagnostic process of channelopathies have been made, the link between a disease and sudden cardiac death remains not fully explained. Evolving data in electrophysiology and genetic testing suggest previously described diseases as complex with multiple underlying genes and a high variety of factors associated with SCD in channelopathies. This review summarizes available, well-established information about channelopathy pathogenesis, genetic basics, and molecular aspects relative to principles of the pathophysiology of arrhythmia. In addition, general information about diagnostic approaches and management is presented. Analyzing principles of channelopathies and their underlying causes improves the understanding of genetic and molecular basics that may assist general research and improve SCD prevention.

Early Repolarization Syndrome Leading to Recurrent Cardiac Arrest in a Young Active Duty Patient

A previously healthy, active duty 37-year-old male experienced recurrent cardiac arrests because of ventricular fibrillation and polymorphic ventricular tachycardia. Initial evaluation did not reveal a clear ischemic, structural, toxic, or metabolic cause. Close monitoring of telemetry before his third cardiac arrest revealed the cause to be early repolarization syndrome (ERS). In this case, we review the diagnosis, epidemiology, and prognostic significance of early repolarization pattern as it relates to ERS. We also discuss acute and long-term treatment strategies for patients with ERS.

Triggers of Ventricular Fibrillation in Patients With Inferolateral J-Wave Syndrome

BACKGROUND

There are few data on ventricular fibrillation (VF) initiation in patients with inferolateral J waves.

OBJECTIVES

This multicenter study investigated the characteristics of triggers initiating spontaneous VF in inferolateral J-wave syndrome.

METHODS

A total of 31 patients (age 37 ± 14 years, 24 male) with spontaneous VF episodes associated with inferolateral J waves were evaluated to determine the origin and characteristics of triggers. The J-wave pattern was recorded in inferior leads in 11 patients, lateral leads in 3, and inferolateral leads in 17.

RESULTS

The VF triggers (n = 37) exhibited varying QRS durations (176 ± 21 milliseconds, range 119-219 milliseconds) and coupling intervals (339 ± 46 milliseconds, range 250-508 milliseconds) with a right (70%) or left (30%) bundle branch block (BBB) pattern. Trigger patterns were associated with J-wave location: left BBB triggers with inferior J waves and right BBB triggers with lateral J waves. Electrophysiologic study was performed for 22 VF triggers in 19 patients. They originated from the left or right Purkinje system in 6 and from the ventricular myocardium in 10 and were undetermined in 6. Purkinje vs myocardial triggers showed distinct electrocardiographic characteristics in coupling interval and QRS-complex duration and morphology. Abnormal epicardial substrate associated with fragmented electrograms was identified in 9 patients, with triggers originating from the same region in 7 patients. Catheter ablation resulted in VF suppression in 15 patients (79%).

CONCLUSIONS

VF initiation in inferolateral J-wave syndrome is associated with significant individual heterogeneity in trigger characteristics. Myocardial triggers have electrocardiographic features distinct from Purkinje triggers, and their origin often colocalizes with an abnormal epicardial substrate.

Electrocardiographic Early Repolarization in an Emergency Setting: The Subtleties of Electrocardiography

The electrocardiographic pattern of early repolarization (ER) is relatively common in the general population. In patients presenting to the emergency room with chest pain, it can be particularly challenging to distinguish ER from life-threatening subtle ST-segment elevation myocardial infarction (STEMI). A 37-year-old male presented to the emergency department with sudden-onset, severe, non-radiating, central chest pain. The ECG showed Q waves in the inferior leads and a widespread end-QRS notch with J-point elevation mimicking ST elevation in the inferior and lateral precordial leads. Initial cardiac biomarkers were within normal limits. Serial cardiac biomarkers were unremarkable. Echocardiography showed no wall motion abnormalities. A review of prior records from a month ago revealed a similar presentation with similar ECG findings when he underwent cardiac catheterization, revealing normal coronary arteries. Since the ECG was unchanged from the prior one with negative cardiac biomarkers and a negative angiographic study a month ago, no further ischemic risk stratification was indicated. Distinguishing ER from subtle STEMI in patients with acute chest pain can be challenging. A good clinical acumen, along with a comparison of prior ECGs, can aid in decision-making.

Early Repolarization Augmentation Mimicking Pseudo-Infarction in a Patient With Diabetic Ketoacidosis and Normokalemia

Early repolarization (ER) changes, characterized by J point elevation with or without ST-segment elevation, are dynamic in their presentation and can be exacerbated by factors such as hypothermia, hypercalcemia, vagotonia, and certain medications. There is limited research regarding the mechanism of these changes and the dynamic changes of ER secondary to diabetic ketoacidosis (DKA). This case report highlights the augmentation of early repolarization changes resembling ST-segment elevation myocardial infarction (STEMI) in a patient with DKA that resolved with the treatment of acidosis. The misinterpretation of ER changes on electrocardiogram (ECG) as STEMI or pericarditis may result in the inappropriate utilization of resources, increased patient risk, and elevated morbidity and mortality. Recognition of the potential of DKA to cause ER changes can potentially avoid these unfavorable outcomes.

Early repolarization: Electrocardiographic cues to distinguish benign from malignant variants

Historically, early repolarization (ER) has been considered a marker of good health as it is more prevalent in athletes, younger persons, and at slower heart rates. However, contemporary reports, largely based on data from resuscitated sudden cardiac arrest patients, suggest an association between ER and an increased risk for sudden cardiac death and the development of malignant ventricular arrhythmias. Therefore, after we present a brief-case presentation, we intend to review a challenging topic in recognition of malignant variants and propose a four-step comprehensive approach to simplify ECG discrimination when assessing ER changes.

Heart Disease and Stroke Statistics-2023 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2023 Statistical Update is the product of a full year's worth of effort in 2022 by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. The American Heart Association strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional COVID-19 (coronavirus disease 2019) publications, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Cardiac Morphofunctional Characteristics of Individuals with Early Repolarization Pattern: A Literature Review

The early repolarization pattern (ERP) is an electrocardiographic phenomenon characterized by the appearance of a distinct J-wave or J-point elevation at the terminal part of the QRS complex. ERP is associated with an increased risk of ventricular arrhythmias in susceptible individuals. The cardiac morphofunctional parameters in subjects with ERP have been characterized mainly by imaging techniques, which suggests that certain changes could be identified in the background of the electrical pathomechanism: however, in this regard, current data are often contradictory or insufficiently detailed. For clarification, a more comprehensive cardiac imaging evaluation of a large patient population is necessary. This review summarizes and analyses the data from the literature related to cardiac morphofunctional characteristics in individuals with ERP.

PR Segment-A Neglected Electrocardiogram Profile in Acute Chest Pain

This case report describes a patient in their 40s who presented to the emergency department with acute chest pain.

Electrocardiographic Changes Associated with Early Repolarization Pattern in Healthy Young Males

Background and Objectives: Early repolarization pattern (ERP) has recently been shown to be related with an increased risk of ventricular arrhythmias in susceptible individuals. Materials and Methods: We studied the ERP-associated ECG changes, with potential clinical relevance, in 220 young (age 22.1 ± 1.6 years), healthy, male subjects using 12-lead ECG recordings. A total of 38 subjects (17.3%) fulfilled the diagnostic criteria for ERP, and a total of 90 ECG characteristics were compared between the groups of subjects with and without ERP. Results: None of the ECGs were pathological, and 22 ECG parameters differed significantly (p < 0.05) between the subjects with and without ERP. Among them, the P wave-related parameters (e.g., average P wave duration: 101.5 ± 9.2 ms vs. 106.8 ± 9.9 ms, p = 0.004) and the presence of fragmented QRS complexes (67.6% vs. 92.1%, p = 0.002) revealed a potential propensity for atrial and ventricular arrhythmogenesis. The time-domain parameters of repolarization, those not corrected for QRS duration, showed shorter values (e.g., Tpeak-Tend interval: 70.9 ± 8.1 ms vs. 67.8 ± 8.0 ms, p = 0.036), reflecting the accelerated repolarization. Conclusions: Certain ECG characteristics seem to be more associated with ERP. The clinical significance of this finding at the individual level needs further prospective investigations.

Electrocardiography is Useful to Predict Postoperative Ventricular Arrhythmia in Patients Undergoing Cardiac Surgery: A Retrospective Study

Background: Preoperative detection of high-/low-risk postoperative ventricular arrhythmia (POVA) patients using a noninvasive method is an important issue in the clinical setting. This study mainly aimed to determine the usefulness of several preoperative electrocardiographic (ECG) markers in the risk assessment of POVA with cardiac surgery.

Method: We enrolled 1024 consecutive patients undergoing cardiac surgery, and a total of 823 patients were included in the study. Logistic regression analysis determined preoperative ECG markers. A new risk predicting model were developed to predict occurrence of POVA, and the receiver operating characteristic curve (ROC) was used to validate this model.

Results: Of these, 337 patients experienced POVA, and 485 patients did not experience POVA in this retrospective study. Among 15 ECG markers, a univariate analysis found a strong association between POVA and preoperative VA, the R-wave in lead aVR, the QRS wave, index of cardiac electrophysiological balance (iCEB), QT interval corrected (QTc), Tpeak–Tend interval (Tpe) in lead V2, the J wave in the inferolateral leads, pathological Q wave, and SV1+RV5&gt;35 mm. Multivariate analysis showed that a preoperative J wave [adjusted odds ratio (AOR): 3.80; 95% CI: 1.88–7.66; p &lt; 0.001], Tpe &gt;112.5-ms (AOR: 2.80; 95% CI: 1.57–4.99; p &lt; 0.001), and SV1+RV5 &gt;35 mm (AOR: 2.92; 95% CI: 1.29–6.60; p = 0.01) were independently associated with POVA. A new risk predicting model were developed in predicting POVA.

Conclusion: The ECG biomarkers including J wave, Tpe &gt;112.5 ms, and SV1+RV5 &gt;35 mm were significantly predicted POVAs. A risk predicting model developed with electrocardiographic risk markers preoperatively predicted POVAs.

Association of early repolarization pattern and ventricular fibrillation in patients with vasospastic angina: A systematic review and meta-analysis

Background

An early repolarization (ER) pattern is a risk factor for ventricular fibrillation (VF) in patients with vasospastic angina (VSA) caused by a coronary artery spasm. However, its detailed characteristics and prognostic value for VF remain unclear. Thus, we investigated the relationship between ER and VF in patients with VSA.

Hypothesis

The ER pattern is associated with VF in patients with VSA.

Methods

In this systematic review and meta‐analysis, we searched PubMed, Embase, Cochrane Library, and Web of Science databases for eligible studies published between January 2011 and December 2020; 8 studies with 1761 patients were included in the final analysis.

Results

The ER pattern significantly predicted adverse cardiovascular events (ACEs) and VF (odds ratio [OR] = 5.13, 95% confidence interval [95% CI]: 3.16–8.35, p < .00001 and OR = 5.20, 95% CI: 3.05–8.87, p < .00001). The presence of ER in the inferior leads increased the VF risk (OR = 7.80, 95% CI: 4.04–15.05, p < .00001), regardless of the J‐point morphology or type of ST‐segment elevation in the ER pattern. A horizontal/descending ST‐segment elevation was significantly associated with VF in patients with or without an ER pattern during a coronary spasm (OR = 2.28, 95% CI: 1.07–4.88, p = .03). However, obstructive coronary artery disease was unrelated to the ER pattern (OR = 0.82, 95% CI: 0.27–2.53, p = .73).

Conclusions

An ER pattern is significantly associated with an increased risk of ACE in patients with VSA. An inferior ER pattern with horizontal/descending ST‐segment elevation confers the highest risk for VF during VSA onset. Nevertheless, the ER pattern is not associated with obstructive coronary artery disease.

Heart Disease and Stroke Statistics-2022 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2022 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population and an enhanced focus on social determinants of health, adverse pregnancy outcomes, vascular contributions to brain health, and the global burden of cardiovascular disease and healthy life expectancy.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

The Role of ECG in the Diagnosis and Risk Stratification of Acute Coronary Syndromes: an Old but Indispensable Tool

PURPOSE OF REVIEW

Since its inception in 1902 by Willem Einthoven, the electrocardiogram (ECG) has fundamentally undergone minimal technological advances. Nevertheless, its clinical utility is critical, and it remains an essential tool to diagnose, risk stratify, and guide reperfusion and invasive strategies in patients with suspected acute coronary syndromes. ECG reading can be demanding, with many healthcare professionals lacking the necessary expertise to accurately interpret them. This is exacerbated by the need to constantly revisit old dogmas pertinent to the interpretation of ECGs.

RECENT FINDINGS

Notably, ECG leads record the global electrical activity of the heart toward and away from each electrode rather than local events. The long-held central paradigm that the various ECG leads record local events underneath specific electrodes should therefore be reassessed. For example, ST segment elevation in leads V1 and V2 usually denote antero-apical rather than septal infarction, often a misnomer utilized by the majority of clinicians. The ECG diagnosis of ST-elevation myocardial infarction (STEMI) is sometimes challenging and discerning it from non-ST-elevation myocardial infarction (NSTEMI) is of paramount importance to implement timely acute reperfusion therapy. In fact, when qualifications for emergency reperfusion therapy are based on STEMI ECG criteria, nearly one-third of cases with acute coronary occlusion are missed. Diagnostic ST elevation in the absence of left ventricular (LV) hypertrophy or left bundle-branch block (LBBB) is defined by a specific set of sex-specific criteria for new ST elevation at the J point in contiguous precordial or limb leads. However, other ECG criteria need to be kept in mind. These include, but are not limited to, new or presumably new left bundle branch block (LBBB), which is often considered as an STEMI-equivalent; ST depression in two or more precordial leads (V1-V4), denoting a true inferolateral transmural myocardial infarction; and the infrequent presentation with hyperacute T-wave changes. As our understanding of the pathology of ischemic reperfusion injury has evolved and following the introduction of new imaging modalities such as cardiac magnetic resonance imaging, we need to re-assess the old dogmas pertinent to the interpretation of ECGs and update the terms and classifications.

Relations Between Cardiac Magnetic Resonance Imaging-Derived Left Ventricular Mass, Early Repolarization, and Cardiovascular Events (from the Dallas Heart Study)

Early repolarization pattern (ERP) is associated with increased mortality in case-control studies, but the mechanism and role of left ventricular mass (LVM) remain unclear. Our objectives were to understand (1) whether ERP associates with adverse outcomes in a multiethnic population and (2) to explore the role of LVM in these associations. Participants from the Dallas Heart Study with an electrocardiogram interpretable for ERP, defined as J point elevation ≥1 mm in 2 contiguous leads, were included. Combined all-cause mortality and nonfatal cardiovascular disease (CVD) events and individual components were assessed using Cox proportional hazards modeling after adjustment for demographics, traditional CVD risk factors, electrocardiogram intervals, and cardiac magnetic resonance imaging-derived factors. Cardiac magnetic resonance imaging-defined LVM was then added to the most fully adjusted model. Of the 2,686 participants, 240 (8.9%) demonstrated ERP. Participants with ERP were more likely to be male and Black, with lower body mass index, greater left ventricular end-diastolic volumes, and LVM. Over a median follow-up of 11 years, the combined end point occurred in 326 patients. Multivariable modeling demonstrated ERP was associated with the combined end point (HR [95% CI] 1.61 [1.14 to 2.26]), all-cause mortality (1.67 [1.00 to 2.80]). However, further adjusting for LVM attenuated the associations of ERP with the primary end point (HR [95% CI] 1.22 [0.85 to 1.77]) and secondary end points of mortality (1.39 [0.80 to 2.41]) and nonfatal CVD (1.05 [0.68 to 1.64]). ERP was associated with increased mortality and nonfatal CVD events, which was attenuated after adjusting for LVM, a previously under-recognized clinical phenotype. Previous associations of ERP with adverse cardiovascular outcomes may be partially explained by greater LVM in those with ERP.

Sudden Cardiac Arrest Secondary to Early Repolarization Syndrome

A healthy 41-year-old man sustained cardiac arrest secondary to ventricular fibrillation. An extensive ischemic, structural, and genetic evaluation did not identify an attributable pathologic condition. Electrocardiograms were notable for early repolarization pattern. Here we review the diagnosis, prevalence, and prognostic significance of the early repolarization syndrome on sudden cardiac death. (Level of Difficulty: Intermediate.).

Early Repolarization in Pediatric Athletes: A Dynamic Electrocardiographic Pattern With Benign Prognosis

Background

Early repolarization pattern (ERP) is considered a common training‐related and benign ECG finding in young adult athletes. Few data exist on ERP in the pediatric athletes population. Therefore, we aimed to evaluate the ERP prevalence, characteristics, and prognosis in pediatric athletes aged ≤16 years.

Methods and Results

Eight‐hundred eighty‐six consecutive pediatric athletes engaged in 17 different sports (mean age, 11.7±2.5 years; 7–16 years) were enrolled and prospectively evaluated with medical history, physical examination, resting and exercise ECGs, and transthoracic echocardiography during their preparticipation screening. Known cardiovascular diseases associated with sudden cardiac death was considered exclusion criteria. Athletes were followed up yearly for 4 years. The prevalence of ERP was 117 (13.2%), equally distributed in both sexes (P=0.072), irrespectively of body mass index and classification of sports. The most common ERP localizations were inferolateral and inferior leads (53.8% and 27.3%, respectively). Notching J‐point morphology was the most prevalent (70%), and rapidly ascending ST elevation (96%) was the most common ST‐segment morphology. Athletes with ERP were older (P<0.001) had lower rest and recovery heart rates (P<0.001), increased precordial and limb R‐wave voltages (P<0.001), increased R/S Sokolow index (P<0.001), and longer PR interval (P=0.006) in comparison with the athletes without ERP. Neither major cardiovascular nor arrhythmic events, nor sudden cardiac death were recorded over a median follow‐up of 4.2 years. One hundred seventeen (80.3%) athletes with ERP exhibited a persistent ERP. ERP localization and J‐point morphology changed during follow‐up in 11 (11.7%) and 17 (18%) of athletes, respectively.

Conclusions

ERP is common in pediatric athletes. It was mostly located in the inferolateral leads and associated with concave ascending ST segment with other training‐related ECG changes. The lack of either sudden cardiac death or cardiomyopathies linked to sudden cardiac death over follow‐up suggests that in pediatric athletes, ERP may be considered a benign training‐related ECG phenomenon with a potential dynamic pattern.

Pediatric athletes' ECG and diagnostic performance of contemporary ECG interpretation criteria

BACKGROUND

Electrocardiographic (ECG) pre-participation screening(PPS) can prevent sudden cardiac death(SCD) but the Interpretation of the athlete's ECG is based on specific criteria addressed for adult athletes while few data exist about the pediatric athlete's ECG. We aimed to assess the features of pediatric athletes' ECG and compared the diagnostic performance of 2017 International ECG recommendation, 2010 European Society of Cardiology recommendation and 2013-Seattle criteria in detecting clinical conditions at risk of SCD.

METHODS

886 consecutive pediatric athletes (mean age 11.7 ± 2.5 years; 7-16-years) were enrolled and prospectively evaluated with medical history, physical examination, resting and exercise ECG and transthoracic echocardiography during their PPS.

RESULTS

The most common physiological ECG patterns in pediatric athletes were isolated left ventricular hypertrophy criteria (26.9%), juvenile T-wave pattern (22%) and early repolarization pattern (13.2%). The most frequent borderline abnormalities were left axis deviation (1.8%) and right axis deviation (0.9%) while T-wave inversion (0.8%) especially located in inferior leads (0.7%) was the most prevalent abnormal findings. Seven athletes (0.79%) were diagnosed with a condition related to SCD. Compared to Seattle and ESC, the International improved ECG specificity (International = 98% ESC = 64% Seattle = 95%) with lower sensitivity (ESC and Seattle 86%vs International 57%). The false-positive rate decreases from 36% of ESC to 2.2% of International but the latter showed a higher false-negative rate(0.34%).

CONCLUSION

Pediatric athletes like the adult counterpart exhibit a high prevalence of ECG abnormalities mostly representing training-related ECG adaptation. The International criteria showed a lower false-positive rate but at the cost of loss of sensitivity.

Why Ablation of Sites With Purkinje Activation Is Antiarrhythmic: The Interplay Between Fast Activation and Arrhythmogenesis

Ablation of sites showing Purkinje activity is antiarrhythmic in some patients with idiopathic ventricular fibrillation (iVF). The mechanism for the therapeutic success of ablation is not fully understood. We propose that deeper penetrance of the Purkinje network allows faster activation of the ventricles and is proarrhythmic in the presence of steep repolarization gradients. Reduction of Purkinje penetrance, or its indirect reducing effect on apparent propagation velocity may be a therapeutic target in patients with iVF.

Heart Disease and Stroke Statistics-2021 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2021 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, an enhanced focus on social determinants of health, adverse pregnancy outcomes, vascular contributions to brain health, the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors related to cardiovascular disease.

RESULTS

Each of the 27 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Prediction of ventricular arrhythmias in patients with a spontaneous Brugada type 1 pattern: the key is in the electrocardiogram

AIMS

There is currently no reliable tool to quantify the risks of ventricular fibrillation or sudden cardiac arrest (VF/SCA) in patients with spontaneous Brugada type 1 pattern (BrT1). Previous studies showed that electrocardiographic (ECG) markers of depolarization or repolarization disorders might indicate elevated risk. We aimed to design a VF/SCA risk prediction model based on ECG analyses for adult patients with spontaneous BrT1.

METHODS AND RESULTS

This retrospective multicentre international study analysed ECG data from 115 patients (mean age 45.1 ± 12.8 years, 105 males) with spontaneous BrT1. Of these, 45 patients had experienced VF/SCA and 70 patients did not experience VF/SCA. Among 10 ECG markers, a univariate analysis showed significant associations between VF/SCA and maximum corrected Tpeak-Tend intervals ≥100 ms in precordial leads (LMaxTpec) (P < 0.001), BrT1 in a peripheral lead (pT1) (P = 0.004), early repolarization in inferolateral leads (ER) (P < 0.001), and QRS duration ≥120 ms in lead V2 (P = 0.002). The Cox multivariate analysis revealed four predictors of VF/SCA: the LMaxTpec [hazard ratio (HR) 8.3, 95% confidence interval (CI) 2.4-28.5; P < 0.001], LMaxTpec + ER (HR 14.9, 95% CI 4.2-53.1; P < 0.001), LMaxTpec + pT1 (HR 17.2, 95% CI 4.1-72; P < 0.001), and LMaxTpec + pT1 + ER (HR 23.5, 95% CI 6-93; P < 0.001). Our multidimensional penalized spline model predicted the 1-year risk of VF/SCA, based on age and these markers.

CONCLUSION

LMaxTpec and its association with pT1 and/or ER indicated elevated VF/SCA risk in adult patients with spontaneous BrT1. We successfully developed a simple risk prediction model based on age and these ECG markers.

The Electrocardiogram in the Differential Diagnosis of Cardiologic Conditions Related to the COVID-19 Pandemic

The World Health Organization (WHO) declared Sars-CoV infection and COVID-19 as a pandemic and global emergency. In addition to viral pneumonia and the severe acute respiratory syndrome (Sars), the heart is affected in some patients due to the detection of biomarkers and reported cases of myocarditis and pericarditis. Therefore, the knowledge of electrocardiogram presentation of these actual infections can guide the choice for the best treatment and can help to reduce misdiagnosis, mainly the acute myocardial infarction, which is the main differential diagnosis.

[Particularities of African descent patient's electrocardiogram]

Particularities of African descent patient's electrocardiogram have been described for many years. Variations such as higher QRS voltage, early repolarization pattern, precordial T-wave inversion and anterior ST segment elevation associated with T-wave inversion are more frequently observed. Ignorance of these variations can lead to misdiagnosis or therapeutic negligence. We present the electrocardiographic particularities attributed to the patient of African origin.

Association of early repolarization pattern with cardiovascular outcomes in middle-aged population: A cohort study

BACKGROUND

Large cohort studies provide conflicting evidence regarding the prognostic value of early repolarization pattern (ERP) in the general population, complicated by the complex or heterogeneous definitions of ERP applied in different studies.

HYPOTHESIS

We hypothesized that ERP was associated with increased cardiovascular risk with the definition of ERP recommended by the expert consensus statements.

METHODS

A total of 13673 middle-aged subjects from the prospective, population-based Atherosclerosis Risk in Communities (ARIC) study were included in this analysis. Cox models were used to estimate the hazard ratios (HRs) adjusted for possible confounding factors. ERP was defined as ST-segment elevation ≥0.1mV at the end of the QRS or J wave on the QRS downstroke in two or more contiguous leads.

RESULTS

Compared with those without ERP, subjects with ERP had a significantly increased risk of developing sudden cardiac death (SCD) (HR, 1.48; 95% CI, 1.08-2.04) and death from coronary heart disease (CHD) (HR, 1.45; 95% CI, 1.10-1.92) after a median follow-up of 20.1 years. ERP was significantly predictive of SCD in females, whites, younger people, and subjects with relatively low cardiovascular risk. ERP with ST-segment elevation appeared to indicate poor cardiovascular outcomes. ERP was associated with an absolute risk increase of 93.3 additional SCDs per 100 000 person-years.

CONCLUSIONS

Our findings suggest that ERP was an independent predictor of SCD and CHD death in the middle-aged biracial population.

Vasospastic angina and overlapping cardiac disorders in patients resuscitated from cardiac arrest

BACKGROUND

Vasospastic angina (VSA) reportedly accounts for one form of sudden cardiac arrest (SCA). Intracoronary acetylcholine (ACh) testing is useful for diagnosing VSA although invasive provocation testing after SCA is a clinical challenge. In addition, even if the ACh test is positive, any causal relationship between VSA and SCA is often unclear because patients with VSA may have other underlying cardiac disorders.

METHODS

A total of 20 patients without overt structural heart disease who had been fully resuscitated from SCA were included. All patients underwent the ACh provocation test and scrutiny such as cardiac computed tomography or magnetic resonance imaging. Patients were followed up for all-cause death or recurrent SCA including appropriate implantable cardioverter defibrillator therapy.

RESULTS

An ACh provocation test was performed 20 ± 17 days after cardiac arrest. Fifteen out of 20 (75.0%) patients had a positive ACh test and 2 (10.0%) had adverse events such as ventricular tachycardia and transient cardiogenic shock during the test. In patients with a positive ACh test, 6 of 15 (40.0%) patients had other overlapping cardiac disorders such as long QT syndrome, Brugada syndrome, cardiac sarcoidosis, myocarditis, or cardiomyopathy. Long-term prognosis was not different regardless of a positive ACh test or the presence of other cardiac disorders overlapping with VSA.

CONCLUSIONS

Three-quarters of the patients who had been resuscitated from SCA had a positive ACh test. Further examinations revealed other overlapping cardiac disorders in addition to VSA in 40% of patients with a positive ACh test.

Autonomic Influences Related to Early Repolarization in Patients Without Structural Heart Disease

This cross-sectional study focused on the association between heart rate variability (HRV) and early repolarization pattern (ERP). It included 1236 patients categorized into three groups: ERP type 1: J-point elevation with notched/slurred QRS; ERP type 2: ST elevation without dominant J-wave; and non-ERP group. Analyzing time-domain indexes include standard deviation of NN (normal-to-normal) RR intervals (SDNN), root mean square of successive difference in NN RR intervals (RMSSD), and proportion of consecutive NN intervals that differ by more than 50 ms (PNN50), there were significant differences between any two groups (all P < 0.01). All time-domain indexes showed: ERP type 2 > ERP type 1 > non-ERP. Multivariate logistic regression analysis revealed that SDNN at nighttime and gender were independently associated with the maximum magnitude of J-point elevation ≧ 0.2 mV. The findings strongly suggested that based on electrocardiogram characteristics, parasympathetic tone denoted by HRV may be related to different types of ERP.

Heart Disease and Stroke Statistics-2020 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports on the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2020 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, metrics to assess and monitor healthy diets, an enhanced focus on social determinants of health, a focus on the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors, implementation strategies, and implications of the American Heart Association's 2020 Impact Goals.

RESULTS

Each of the 26 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, healthcare administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Role of electrocardiogram in diagnosis of inherited arrhythmia syndromes

The aim of this paper is to define the role of electrocardiogram (ECG) in diagnosis, prognosis and treatment of inherited arrhythmias syndromes. Brugada Syndrome diagnosis is established in presence of coved type ST-segment elevation (type 1) ≥ 2mm in ≥ 1 of the right precordial leads V1 to V2. Long QT Syndrome is diagnosed when one of factors is present: QTc ≥ 480 ms, QTc ≥ 460 ms in patients with unexplained syncope, pathogenic mutation or risk score > 3. Polymorphic ventricular tachycardia (VT) Torsades de Pointes have specific presentation in ECG with characteristic illusion of the QRS complex twisting around the isoelectric baseline. The early repolarization pattern in patients resuscitated from otherwise unexplained ventricular fibrillation (VF)/polymorphic VT or in a sudden cardiac death (SCD) victims makes diagnosis of Early Repolarization Syndrome. Short QT Syndrome is diagnosed in the presence of a QTc ≤ 340 ms or QTc < 360 ms with one or more of the following factors: a pathogenic mutation, survival of a VT/VF episodes, family history of this disease and SCD in family at age ≤ 40. Catecholaminergic Polymorphic Ventricular Tachycardia has ECG appearance of bidirectional VT or polymorphic ventricular premature beats or VT induced by exercise or catecholamine.

Impact of Ethnicity on the Prevalence of Early Repolarization Pattern in Children: Comparison Between Caucasian and African Populations

The patterns and prevalence of early repolarization pattern (ER) in pediatric populations from ethnic backgrounds other than Caucasian have not been determined. Black African children (ages 4-12) from north-west Madagascar were prospectively recruited and their ECGs compared with those of age- and sex-matched Caucasian ethnicity individuals. ER was defined by ≥ 0.1 mV J-point elevation in at least two contiguous inferior and/or lateral ECG leads. A total of 616 children were included. There was a trend toward a higher frequency of ER in the Africans compared to the Caucasians (23.3% vs. 17.1%, respectively, p = 0.053). The subtype (slurred vs. notched) and location of ER (lateral, inferior, or inferior-lateral) were significantly different in the two groups (p < 0.001 and p = 0.020, respectively). There was no significant difference in the number of high-risk ECG features of ERP (i.e., horizontal/descendent pattern, inferior or inferior-lateral location or J-waves ≥ 2 mm) between African and Caucasian children. On the multivariate analysis, African ethnicity was an independent predictive factor of ER (OR 3.57, 95% CI 2.04-6.25, p < 0.001). African children have an increased risk of ER compared to Caucasian counterparts. Future studies should clarify the clinical and prognostic significance of ER in the pediatric population, and whether ethnicity has an impact on the outcomes.

Occluded or Not?

This report describes the case of a 48-year-old man whose electrocardiogram after cardiopulmonary resuscitation showed up-sloping ST-segment depression at the J point in precordial leads combined with tall symmetrical T waves. This electrocardiographic pattern corresponded to de Winter syndrome and is related to proximal left anterior descending coronary artery occlusion. (Level of Difficulty: Beginner.)

Prolongation of The Activation Time in Ischemic Myocardium is Associated with J-wave Generation in ECG and Ventricular Fibrillation

J-wave pattern has been recognized as an arrhythmic risk marker, particularly in myocardial infarction patients. Mechanisms underlying J-wave development in ischemia remain unknown. In myocardial infarction model, we evaluated activation time delay as a prerequisite of J-wave appearance and predictor of ventricular fibrillation. Body surface ECGs and myocardial unipolar electrograms were recorded in 14 anesthetized pigs. 48 intramural leads were positioned across ventricular free walls and interventricular septum. Myocardial ischemia was induced by ligation of the left anterior descending coronary artery and the recordings were done during 40-minute coronary occlusion. The local activation times were determined as instants of dV/dt minimum during QRS complex in unipolar electrograms. During occlusion, ventricular local activation time prolonged in the middle portion of the left ventricular free wall, and basal and middle portions of septum, while J-waves appeared in precordial leads in 11 animals. In logistic regression and ROC curve analyses, activation time delay at a given time-point was associated with J-wave development, and a longer activation time was associated with ventricular fibrillation appearance. In experimental coronary occlusion, activation delay in ischemic myocardium was associated with generation of the J waves in the body surface ECG and predicted ventricular fibrillation.

Early Repolarization vs. Acute Pericarditis Morphology: A Case Report of Electrocardiographic Mimicry

A 27-year-old male presented to the outpatient clinic with a two-week history of daily episodes of palpitations, chest pain, and shortness of breath. He also complained of fatigue and nausea that continued after he recovered from an upper respiratory infection (URI) one month prior. Of note, he described the chest pain as increasing in intensity when sitting or standing upright. Auscultation revealed regular rate and rhythm with no audible rubs or murmurs. An electrocardiogram (ECG) was performed and showed diffuse ST-segment elevations that the machine interpreted as pericarditis. Based on the patient’s symptoms and ECG findings, he was sent for an evaluation by cardiology. After he failed a trial of non-steroidal anti-inflammatory drugs (NSAIDs), the patient was started on colchicine and his symptoms ultimately resolved within a few weeks. Review of his records showed an ECG performed in the emergency department (ED) a year prior demonstrated morphology consistent with early repolarization (ER). The ECG morphology of ER, acute pericarditis (AP), and even acute myocardial infarction (AMI) can often be similar and difficult to differentiate. In this patient, confusing ER with AP may have led to unnecessary evaluation and treatment by a specialist.

PR depression with multi‑lead ST elevation and ST depression in aVR: Is it always acute pericarditis?

The classic electrocardiographic (ECG) manifestation of stage I of acute pericarditis is diffuse ST elevation and PR depression with ST depression in lead aVR. One of the most common conditions, that is often confused with acute pericarditis, is the benign diffuse ST elevation, termed "early repolarization with ST elevation" (ERSTE). ERSTE often presents with diffuse ST elevation in the inferior and anterolateral leads, with or without terminal QRS notching or slurring. As ERSTE often presents with ST elevation in leads I and II, frequently there is concomitant ST depression in lead aVR, similar to the acute pericarditis ECG pattern. Moreover, PR depression in the inferior leads and/or PR elevation in lead aVR is often seen. Here we describe four patients with ERSTE, all had ST elevation in II with either ST elevation or isoelectric ST in lead I and concomitant ST depression in aVR. Two also had PR depression in the inferior leads. None of the patients had clinical symptoms or signs of acute pericarditis. In conclusion, diffuse ST elevation in the inferolateral leads associated with ST depression in aVR and even with PR segment depression is commonly found in ERSTE and should not be considered as pathognomonic of only acute pericarditis.

Early repolarization pattern as a predictor of atrial fibrillation recurrence following radiofrequency pulmonary vein isolation

BACKGROUND

Early repolarization patterns (ERP) have been found to be associated with poor cardiovascular end points. We aimed to evaluate the ERP prevalence among patients with structurally normal hearts undergoing radiofrequency (RF) pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) ablation and its association with the AF recurrence.

METHODS

All consecutive patients who underwent RF-PVI as index procedure for paroxysmal AF in our center were evaluated.

EXCLUSION CRITERIA

structural heart disease, ongoing use of Class I/III antiarrhythmics, complete-bundle-branch-block. Lateral (I, aVL, V₅ -V₆ ), inferior (II, III, aVF), or infero-lateral (both) ERP were defined in baseline ECG as horizontal/downsloping J-point elevation ≥1 mm in two consecutive leads with QRS slurring/notching. Documented episodes of AF lasting ≥30 s were considered recurrence.

RESULTS

Of 701 cases, 434 patients (305 males, 58 ± 11 years) were included for analysis. ERP observed in 67 patients (15.4%) (Infero-lateral n = 26, inferior n = 23, lateral n = 18) which were significantly younger, demonstrating longer PR-interval and lower heart rates. At a mean follow-up of 22.1 ± 9.7 months, AF recurrences were found in 107 patients (24.6%). In middle-aged patients (≥40-<60 years; n = 206, 79% male), those with an infero-lateral ERP had higher recurrence compared with the ones without (56.3% vs. 19%; p = 0.002). Infero-lateral ERP was significantly predicting recurrence (HR 2.42, 95% CI 1.21-4.82; p = 0.01).

CONCLUSION

Early repolarization patterns was more prevalent in our AF population than in the general population. Infero-lateral ERP in baseline ECG might predict AF recurrence in the follow-up after RF-PVI in middle-aged patients.

The Prognostic Value of Early Repolarization Pattern for the Ventricular Tachyarrhythmias of Acute Myocardial Infarction Patients: A Meta-Analysis

Several studies have indicated that early repolarization (ER) is a risk factor for ventricular tachyarrhythmias (VTAs) in acute myocardial infarction (AMI) patients. The prognostic values of ER detail characteristics except J-point morphology, and inferior leads ER location for VTAs are still unclear. We searched PubMed, Embase, and the Cochrane Library for eligible studies up to March 4, 2019. Studies to investigate the relationship between ER and the incidence of VTAs in AMI patients were extracted. A total of 10 studies with 2,672 participants were included in the analysis. ER significantly predicted the incidence of VTAs (odds ratio [OR] 3.62, 95% confidence intervals [CI] 2.77-4.73), regardless of the type of AMI. The presence of ER before AMI (OR 5.58, 95% CI 3.41 to 9.12) and after AMI (OR 3.02, 95% CI 2.19-4.15) increased the risk of VTAs. The prognostic value of ER for VTAs in the long follow-up (≥30 days) (OR 2.39, 95% CI 1.59-3.59) fell by half compared to the short follow-up duration (<30 days) (OR 4.97, 95% CI 3.48-7.09). Patients with ER displayed a higher risk of developing ventricular fibrillation (VF) (OR 6.94, 95% CI 3.87-12.43) than those without ER. However, neither J-point elevation with OR = 2.48 nor lateral leads' ER location with OR = 3.83 remarkably increased the risk of VTAs in patients with AMI. ER is significantly associated with increasing risk of VTAs, particularly VF, in AMI patients. This relationship is weaker in the 30-day follow-up and is not reinforced by J-point elevation and lateral leads' ER location.

Waveform prototype-based feature learning for automatic detection of the early repolarization pattern in ECG signals

OBJECTIVE

Our aim was to develop an automated detection method, for prescreening purposes, of early repolarization (ER) pattern with slur/notch configuration in electrocardiogram (ECG) signals using a waveform prototype-based feature vector for supervised classification.

APPROACH

The feature vectors consist of fragments of the ECG signal where the ER pattern is located, instead of abstract descriptive variables of ECG waveforms. The tested classifiers included linear discriminant analysis, k-nearest neighbor algorithm, and support vector machine (SVM).

MAIN RESULTS

SVM showed the best performance in Friedman tests in our test data including 5676 subjects representing 45 408 leads. Accuracies of the different classifiers showed results well over 90%, indicating that the waveform prototype-based feature vector is an effective representation of the differences between ECG signals with and without the ER pattern. The accuracy of inferior ER was 92.74% and 92.21% for lateral ER. The sensitivity achieved was 91.80% and specificity was 92.73%.

SIGNIFICANCE

The algorithm presented here showed good performance results, indicating that it could be used as a prescreening tool of ER, and it provides an additional identification of critical cases based on the distances to the classifier decision boundary, which are close to the 0.1 mV threshold and are difficult to label.

Electrophysiological Basis for Early Repolarization Syndrome

During last centuries, Early Repolarization pattern has been interpreted as an ECG manifestation not linked to serious cardiovascular events. This view has been challenged on the basis of sporadic clinical observations that linked the J-wave with ventricular arrhythmias and sudden cardiac death. The particular role of this characteristic pattern in initiating ventricular fibrillation has been sustained by clinical descriptions of a marked and consistent J-wave elevation preceding the onset of the ventricular arrhythmia. Until now, Early Repolarization syndrome patients have been evaluated using ECG and theorizing different interpretations of the findings. Nonetheless, ECG analysis is not able to reveal all depolarization and repolarization properties and the explanation for this clinical events. Recent studies have characterized the epicardial substrate in these patients on the basis of high-resolution data, in an effort to provide insights into the substrate properties that support arrhythmogenicity in these patients. An overview for the current evidence supporting different theories explaining Early Repolarization Syndrome is provided in this review. Finally, future developments in the field directed toward individualized treatment strategies are examined.

Electrocardiography in athletes: normal and abnormal findings

Many sporting organisations recommend a pre-participation ECG to screen for disorders which predispose to sudden cardiac arrest (SCA). The ability of the ECG to perform accurately is dependent on the ECG criteria used and the experience of the operator. There have been several ECG criteria over the last decade, though these were recently superseded with the publication of the 'International Consensus Criteria for ECG Interpretation in Athletes'. These criteria use the latest evidence to improve specificity while maintaining sensitivity for ECG-detectable pathologies associated with SCA. Accordingly, this review describes the normal, borderline and abnormal ECG findings in an asymptomatic athlete aged 12-35 years.