Characteristics of “malignant” vs. “benign” electrocardiographic patterns of early repolarization

A case of early repolarization syndrome in which hyponatremia and coronary vasospasms induced ventricular fibrillation

A 60-year-old man was referred to our hospital presenting with unconsciousness due to severe hyponatremia. The twelve‑lead ECG on admission exhibited prominent J waves in the inferolateral leads. During the treatment for hyponatremia, ventricular fibrillation (VF) occurred and the electrogram (ECG) after the VF incident exhibited marked ST elevation in the inferolateral leads. An Ach provocation test induced vasospasms in the right and left coronary arteries and J wave augmentation, suggesting a high risk for vasospastic angina. Finally, a subcutaneous implantable cardioverter defibrillator was implanted in the patient. We hereby discuss the possible contribution of hyponatremia to VF episodes in early repolarization syndrome based on the present case.

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.

Early repolarization in adolescent athletes: A gender comparison of ECG and echocardiographic characteristics

BACKGROUND

The early repolarization pattern (ERp) is an electrocardiographic finding previously associated with arrhythmic risk in adults. The purpose of this study is to evaluate the prevalence and characteristics of ERp in a group of adolescent athletes according to gender. Furthermore, potential associations with clinical, electrocardiographic, and echocardiographic parameters are explored.

METHODS

In this cross-sectional study young athletes (age < 18 years) were consecutively enrolled during the annual pre-participation evaluation, undergoing also transthoracic echocardiography assessment from January 2015 to March 2020.

RESULTS

The prevalence of ERp was 27% in the whole population. Athletes with ERp were more frequently men practicing endurance sports. Women with ERp showed lower heart rate at rest, greater posterior, and relative ventricular wall thickness than those without ERp. Men with ERp presented higher systolic blood pressure at peak exercise, greater septal wall thickness, and indexed left ventricular mass than those without ERp. Both genders with ERp showed increased QRS voltage and narrower QRS duration. The ERp phenotype in men was more frequently notched with higher amplitude and ascending ST segment. Women's ERp presented more frequently a slurred morphology, especially in the inferior leads, and horizontal ST slope. No differences emerged in the occurrence of arrhythmias at rest and during maximal exercise test between groups, even considering higher risk phenotypes.

CONCLUSIONS

ERp is an ECG finding compatible with normal cardiac adaptations to training in young athletes. ERp demonstrated gender differences regarding phenotypes previously associated with increased cardiovascular risk, not showing any differences in arrhythmias during maximal exercise test.

Early repolarisation among athletes

Objectives

Traditionally, early repolarisation (ER) is considered a benign ECG variant, predominantly found in youths and athletes. However, a limited number of studies have reported an association between ER and the incidental occurrence of ventricular fibrillation or sudden cardiac death. Yet definite, direct comparisons of the incidence of ER in unselected, contemporary populations in athletes as compared with non-athletes and across different sports are lacking. This study therefore aimed to investigate whether ER is more common among athletes as compared with non-athletes, and if ER patterns differ between sport disciplines based on static and dynamic intensity.

Methods

To assess ER we retrospectively analysed ECGs of 2241 adult subjects (2090 athletes, 151 non-athletes), who had a sports medical screening between 2010 and 2014 in an outpatient clinic. The outcome was tested for confounders in a multivariable logistic regression analysis.

Results

ER was found in 502 athletes (24%). We found a 50% higher prevalence of ER in the athlete group compared with the control group (OR 1.5 (SE 0.34), adjusted 95% CI 1.0 to 2.4) in multivariable analysis. A 30% higher prevalence of ER in the inferior leads only (OR 1.3 (SE 0.38), adjusted 95% CI 0.74 to 2.3), a 120% higher prevalence of ER in the lateral leads only (OR 2.2 (SE 1.0), adjusted 95% CI 0.87 to 5.4), and a 20% higher prevalence of ER in the inferior and lateral leads (OR 1.2 (SE 0.49), adjusted 95% CI 0.55 to 2.7) was found in athletes.

Conclusion

Athletes had a 50% higher prevalence of ER and a 30% higher prevalence of ER in the inferior leads specifically. There was no association between training duration or sports discipline and ER.

Epicardial Substrate as a Target for Radiofrequency Ablation in an Experimental Model of Early Repolarization Syndrome

BACKGROUND

Early repolarization syndrome (ERS) is an inherited cardiac arrhythmia syndrome associated with sudden cardiac death. Approaches to therapy are currently very limited. This study probes the mechanisms underlying the electrocardiographic and arrhythmic manifestation of experimental models of ERS and of the ameliorative effect of radiofrequency ablation.

METHODS

Action potentials, bipolar electrograms, and transmural pseudo-ECGs were simultaneously recorded from coronary-perfused canine left ventricular wedge preparations (n=11). The I_to agonist NS5806 (7-10 μmol/L), calcium channel blocker verapamil (3 μmol/L), and acetylcholine (1-3 μmol/L) were used to pharmacologically mimic the effects of genetic defects associated with ERS.

RESULTS

The provocative agents induced prominent J waves in the ECG secondary to accentuation of the action potential notch in epicardium but not endocardium. Bipolar recordings displayed low-voltage fractionated potentials in epicardium because of temporal and spatial variability in appearance of the action potential dome. Concealed phase 2 reentry developed when action potential dome was lost at some epicardial sites but not others, appearing in the bipolar electrogram as discrete high-frequency spikes. Successful propagation of the phase 2 reentrant beat precipitated ventricular tachycardia/ventricular fibrillation. Radiofrequency ablation of the epicardium destroyed the cells displaying abnormal repolarization and thus suppressed the J waves and the development of ventricular tachycardia/ventricular fibrillation in 6/6 preparations.

CONCLUSIONS

Our findings suggest that low-voltage fractionated electrical activity and high-frequency late potentials recorded from the epicardial surface of the left ventricle can identify regions of abnormal repolarization responsible for ventricular tachycardia/ventricular fibrillation in ERS and that radiofrequency ablation of these regions in left ventricular epicardium can suppress ventricular tachycardia/ventricular fibrillation by destroying regions of ER.

An early repolarization pattern and L-IIB type of isolated single coronary artery anomaly in a patient who suffered sudden cardiac arrest: A fatal coexistence

The early repolarization pattern and single coronary artery (SCA) anomaly are rare causes of sudden cardiac arrest. The relationship between the early repolarization pattern and idiopathic ventricular fibrillation has previously been reported. Here, we describe a case of an early repolarization pattern and L-IIB type of isolated SCA anomaly in a patient who suffered a sudden cardiac arrest.

Experimental verification of the value of the Tpeak -Tend interval in ventricular arrhythmia inducibility in an early repolarization syndrome model

INTRODUCTION

In patients with early repolarization patterns on ECG, many researchers have studied to find predictors of fatal arrhythmia. However, there are no satisfying clinical predictors. We evaluated the value of the T_peak -T_end interval on pseudo-ECG in canine myocardial wedge preparation models of early repolarization syndrome.

METHODS AND RESULTS

Transmural pseudo-ECG and endocardial/epicardial action potentials were recorded from coronary-perfused canine left ventricular wedge preparations (n = 34). The I_to agonist NS5806 (8-10 µM), the calcium channel blocker verapamil (3 µM) and acetylcholine (2-3 µM) were used to mimic the disease model. A ventricular arrhythmia induction test was performed. QT_peak , QT_end , T_peak -T_end , and T_peak -T_end /QT_end were measured at 15 to 20 minutes after the provocative agent infusion. Polymorphic ventricular tachycardias (pVT) developed in 23 of the 34 preparations (67%). The maximal values of T_peak -T_end and T_peak -T_end /QT_end were recorded just before pVT induction. At baseline, without the provocative agents, T_peak -T_end and T_peak -T_end /QT_end were not different between pVT-induced and pVT-noninduced preparations. The T_peak -T_end of the pVT-induced preparations was longer than that of non-induced preparations (58 ± 26.8 msec vs 33 ± 6.8 msec, P < .001). The T_peak -T_end /QT_end of pVT- induced preparations was larger than that of noninduced preparations (0.220 ± 0.1017 vs 0.128 ± 0.0312, P < .001). The transmural and epicardial dispersion of repolarization of pVT-induced preparations were larger than those of pVT-noninduced preparations. The transmural dispersion of repolarization showed a positive correlation with T_peak -T_end .

CONCLUSION

T_peak -T_end predicted malignant ventricular arrhythmias in early repolarization syndrome models. T_peak -T_end reflects the repolarization heterogeneity of ventricular myocardium.

The effect of exercise on the ECG criteria for early repolarization pattern

OBJECTIVE

To determine the effect of exercise and heart rate on the early repolarization (ER) pattern; focusing on the new criteria for identification of ER.

METHODS

The ECG measurements on the terminal QRS notch or slur found in early repolarization were quantitated before, during and after exercise; specifically: (i) the amplitude at the onset of the notch (J_o) (ii) the amplitude at the peak of the notch (J_p), (iii) the amplitude at the end of the notch (J_t), (iv) the duration from J_o to J_p (D₁) and (v) the duration from J_o to J_t (D₂).

RESULTS

All individuals (N = 21) fulfilling the criteria for ER showed complete disappearance of ER after 3 min of exercise. After 5 min of recovery, 29% of subjects showed return of the ER. The return of ER was dynamic with QRS notching of varying extent, without ST elevation, being evident first. The relationship between heart rate and ER was significant and nonlinear, best fit by a second-order polynomial, suggesting that changes in heart rate with exercise was a factor influencing the presence of the ER pattern and the parameters that define ER.

CONCLUSION

Each of the newly defined characteristics of the ER are modified and eventually disappear with exercise. The return of ER was dynamic with QRS notching of varying extent being evident first. The changes correlated with variations in heart rate, during both exercise and recovery, suggesting, in part, a role in the underlying mechanism of ER.

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.

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.

ST elevation: Differential diagnosis and caveats. A comprehensive review to help distinguish ST elevation myocardial infarction from nonischemic etiologies of ST elevation

Prompt diagnosis of acute ST segment elevation myocardial infarction (STEMI) by the initial ECG is important in order to perform an urgent coronary angiography as soon as possible and achieve successful revascularization, therewith improving mortality and morbidity. Several diseases and conditions can mimic an acute myocardial infarction (AMI) but may not benefit from a (percutaneous) revascularization strategy. This narrative clinical review will discuss the ECG features of some of the causes of non-ischemic ST segment elevation to facilitate early recognition, prevent wrongful diagnosis and improve treatment outcomes.

A meta-analysis on the prognostic significance of inferolateral early repolarization pattern in Brugada syndrome

Aims

The early repolarization (ER) pattern has been linked to an increased risk for arrhythmic death in various clinical settings. There are limited and conflicting data regarding the prognostic significance of ER pattern in Brugada syndrome (BS). The aim of this meta-analysis was to provide a detailed analysis of the currently available studies regarding the arrhythmic risk in patients with BS and ER pattern.

Methods and results

Current databases were searched until May 2015. A random-effect meta-analysis of the effect of ER pattern on the incidence of arrhythmic events in patients with BS was performed. Five studies were included comprising a total of 1375 patients with BS. An ER pattern was reported in 177 patients (12.8%). During follow-up (44.9-93 months), 143 patients (10.4%) suffered an arrhythmic event. Overall, BS patients with ER pattern displayed an increased risk of arrhythmic events compared to patients without ER (OR 3.29, 95% CI: 2.06 to 5.26, P < 0.00001; Heterogeneity: P = 0.11, I2 = 48%). Three studies provided data regarding ER pattern location. Inferior, lateral, or inferolateral ER pattern location was observed in 20.3%, 32.2%, and 48%, respectively. An inferolateral ER location conferred the higher arrhythmic risk (OR 4.87, 95% CI: 2.64 to 9.01, P< 0.00001; Heterogeneity: P = 0.85, I2 = 0%).

Conclusion

This meta-analysis suggests that the ER pattern is associated with a high risk of arrhythmic events in patients with BS. In particular, BS patients with inferolateral ER (global ER pattern) displayed the highest arrhythmic risk.

Progression of early repolarization patterns at a four year follow-up in a female flight crew population: Implications for aviation medicine

BACKGROUND

To assess the prevalence, the appearance, and the distribution, as well as the fluctuation over time of early repolarization patterns after four years in a female population derived from the French aviation sector.

METHODS

This was a retrospective longitudinal study from 1998 to 2010 of a population of female employees who received a full clinical examination and an electrocardiogram (ECG) upon their recruitment and after a period of four years.

RESULTS

A total of 306 women were included (average of 25.87 ± 3.3 years of age). The prevalence of early repolarization was 9.2%. The most common appearance was J-point slurring for 64.3% (i.e. 20/28 subjects) that occurred in the inferior leads for 28.6% (i.e. 8/28 subjects). After four years, the prevalence was 7.5%, with a regression of this aspect in five of the subjects. There were no changes in the ECG in terms of the distribution and the appearance among the 23 subjects for whom the aspect persisted. Over the course of this four year period all of the subjects remained asymptomatic.

CONCLUSIONS

Early repolarization in this largely physically inactive female population was common, and it fluctuated over time. At present, no particular restrictions can be placed on asymptomatic flight crew who exhibit this feature in the absence of a prior medical history for heart disease.

12-Lead electrocardiogram as a predictor of sudden cardiac death: from epidemiology to clinical practice

Sudden cardiac death (SCD) causes a high burden of premature deaths in the population affecting subjects of all ages. The identification of subjects at high risk for SCD is of great importance as the prevention of many of these events would be possible with the treatment of underlying cardiac diseases and the use of implantable cardioverter-defibrillators (ICD). However, the current selection of patients for ICD therapy is based solely on left ventricular ejection fraction, and thus a substantial portion of patients at high risk does not qualify for the therapy. Role of the standard electrocardiogram (ECG) in SCD risk stratification has been under active research during the last decade and multiple abnormalities of depolarization and repolarization on the ECG associated with an increased risk of SCD have been identified. In this review, we describe the basic pathophysiological principles behind these changes. We also review the current knowledge of the prognostic significance of ECG predictors of SCD in the general population, and in patients with coronary heart disease (CHD), heart failure, cardiomyopathies, and in inheritable arrhythmia syndromes. Also, insights into the novel digital ECG signal processing techniques are provided.

Fever-Induced Brugada Syndrome Is More Common Than Previously Suspected: A Cross-Sectional Study from an Endemic Area

BACKGROUND

Brugada syndrome (BrS) is defined as presenting of type-1 Brugada pattern (BrP). BrS can also be induced by fever. This study demonstrated a highest prevalence of fever-induced BrS ever reported.

METHOD

During May 2014, febrile (oral temperature ≥ 38 °C) and nonfebrile patients underwent standard and high leads (V1 and V2 at 2nd intercostal space) electrocardiogram. Risk factor and cardiac symptoms were recorded. Patients with a persistent of type-1 BrP after fever had subsided were excluded. The prevalence of BrS, type-2 BrP and early repolarization pattern (ERP) were demonstrated.

RESULTS

A total of 401 patients, 152 febrile, and 249 nonfebrile, were evaluated. BrS was identified in six febrile patients (five males and one female) and two males in nonfebrile patients. The study demonstrated higher prevalence of BrS in febrile group compared to nonfebrile group (4.0% vs 0.8%, respectively, P = 0.037). Among fever-induced BrS patients, three patients (50.0%) experienced cardiac symptoms before and at the time of presentation and two patients (33.3%) had history of first-degree relative sudden death. No ventricular arrhythmia was observed. All of type-1 BrP disappeared after fever had subsided. We found no difference in prevalence of type-2 BrP in febrile and nonfebrile group (2.0% vs 2.8%, respectively, P > 0.05) as well as ERP (3.3% vs 6.4%, respectively, P > 0.05).

CONCLUSIONS

Our study showed a highest prevalence of fever induced BrS ever reported. A larger study of prevalence, risk stratification, genetic test and management of fever-induced BrS should be done, especially in an endemic area.