New Electrocardiographic Criteria for Discriminating Between Brugada Types 2 and 3 Patterns and Incomplete Right Bundle Branch Block

Brugada Syndrome and Exercise: Is It Time for a Paradigm Change?

BACKGROUND

Despite the multiple benefits of exercise for health, exercise in the presence of arrhythmic disorders can trigger adverse clinical events, including sudden cardiac death (SCD). The aim of this narrative review is to summarize the most recent recommendations regarding physical activity and exercise in individuals with Brugada Syndrome (BrS).

METHODS

An advanced literature search was performed on the Pubmed and clinicaltrials.gov databases and published articles/clinical trials registered until September 2024 were analyzed. The final analysis included 33 articles.

RESULTS

Despite initial reports suggesting a higher risk of SCD in BrS, the risk is not as high as expected, and there is no evidence that exercise is an independent predictor. Therefore, scientific recommendations have become less restrictive. However, consensus on risk scores is lacking, making the evaluation of BrS a real challenge. The most recent recommendations emphasize individual evaluation, risk stratification, shared decision-making, and general preventive measures, allowing asymptomatic BrS patients as well as genotype positive/phenotype negative patients to participate in competitive sports, excluding sports under extreme conditions. Regarding patients with an implantable cardioverter defibrillator, both leisure and competitive sports may be considered in asymptomatic patients, avoiding contact sports.

CONCLUSIONS

Research on the relationship between exercise and cardiovascular disease is evolving, but evidence-based recommendations for sports in BrS patients are scarce and further studies are needed.

Brugada Syndrome in Sports Cardiology: An Expert Opinion Statement of the Italian Society of Sports Cardiology (SICSport)

Brugada syndrome (BrS) is a genetic disorder marked by a characteristic electrocardiogram (ECG) pattern of ST-segment elevation and T-wave inversion in right precordial leads, which is associated with an increased risk of ventricular fibrillation in the absence of structural heart disease. Despite advancements in understanding its epidemiology, pathophysiology, and treatment, there is considerable variability in how sports cardiologists approach BrS. This expert opinion by the Italian Society of Sports Cardiology (SICSPORT) aim to review the current definition, diagnosis, epidemiology, genetics, risk stratification, and treatment of BrS and provide guidance for sport eligibility provides guidance for sports doctors and cardiologists in assessing competitive sports eligibility in athletes with BrS. A multiparametric approach to diagnosis and risk stratification is recommended, noting that the presence of a Brugada ECG pattern (BrP) does not confirm a BrS diagnosis. The risk of sudden cardiac death (SCD) is low in asymptomatic individuals with type 1 BrP, especially those with a drug-induced pattern. Pharmacological testing is not required for type 2 or 3 patterns without other risk factors. Low-risk individuals do not require therapy, while intermediate or high-risk patients may need pharmacological treatment, ICD implantation, or ablation. Asymptomatic individuals with type 2 or 3 BrP, no family history of SCD, and no other risk factors may be eligible for competitive sports, as well as asymptomatic type 1 BrP without risk factors and negative electrophysiological study. Conversely, sports eligibility should be denied in patients with BrS who have a history of syncope or cardiac arrest (high-risk subjects), regardless of ICD presence.

Predicting and Recognizing Drug-Induced Type I Brugada Pattern Using ECG-Based Deep Learning

BACKGROUND

Brugada syndrome (BrS) has been associated with sudden cardiac death in otherwise healthy subjects, and drug-induced BrS accounts for 55% to 70% of all patients with BrS. This study aims to develop a deep convolutional neural network and evaluate its performance in recognizing and predicting BrS diagnosis.

METHODS AND RESULTS

Consecutive patients who underwent ajmaline testing for BrS following a standardized protocol were included. ECG tracings from baseline and during ajmaline were transformed using wavelet analysis and a deep convolutional neural network was separately trained to (1) recognize and (2) predict BrS type I pattern. The resultant networks are referred to as BrS-Net. A total of 1188 patients were included, of which 361 (30.3%) patients developed BrS type I pattern during ajmaline infusion. When trained and evaluated on ECG tracings during ajmaline, BrS-Net recognized a BrS type I pattern with an AUC-ROC of 0.945 (0.921-0.969) and an AUC-PR of 0.892 (0.815-0.939). When trained and evaluated on ECG tracings at baseline, BrS-Net predicted a BrS type I pattern during ajmaline with an AUC-ROC of 0.805 (0.845-0.736) and an AUC-PR of 0.605 (0.460-0.664).

CONCLUSIONS

BrS-Net, a deep convolutional neural network, can identify BrS type I pattern with high performance. BrS-Net can predict from baseline ECG the development of a BrS type I pattern after ajmaline with good performance in an unselected population.

Prevalence of Brugada electrocardiographic pattern in adult population - A community-based study from Kerala, South India

There is no data for Brugada electrocardiographic pattern (BrEP) from India. In a cross-sectional study of men and women between the ages 20-79 years, electrocardiograms were analyzed following the 2002 consensus. The overall prevalence of BrEP was 1.06 % (95 % CI 0.76, 1.35). There were two cases type I (0.04 %; 95 % CI 0.01, 0.06) and forty-seven type II/III (1.01 %; 95 % CI 1.02, 1.35); the pattern was markedly higher in men. In this study, BrEP was slightly less prevalent compared to South Asia but more than in the west.

Electrocardiographic temporo-spatial assessment of depolarization and repolarization changes after epicardial arrhythmogenic substrate ablation in Brugada syndrome

Aims

In Brugada syndrome (BrS), with spontaneous or ajmaline-induced coved ST elevation, epicardial electro-anatomic potential duration maps (epi-PDMs) were detected on a right ventricle (RV) outflow tract (RVOT), an arrhythmogenic substrate area (AS area), abolished by epicardial-radiofrequency ablation (EPI-AS-RFA). Novel CineECG, projecting 12-lead electrocardiogram (ECG) waveforms on a 3D heart model, previously localized depolarization forces in RV/RVOT in BrS patients. We evaluate 12-lead ECG and CineECG depolarization/repolarization changes in spontaneous type-1 BrS patients before/after EPI-AS-RFA, compared with normal controls.

Methods and results

In 30 high-risk BrS patients (93% males, age 37 + 9 years), 12-lead ECGs and epi-PDMs were obtained at baseline, early after EPI-AS-RFA, and late follow-up (FU) (2.7-16.1 months). CineECG estimates temporo-spatial localization during depolarization (Early-QRS and Terminal-QRS) and repolarization (ST-Tpeak, Tpeak-Tend). Differences within BrS patients (baseline vs. early after EPI-AS-RFA vs. late FU) were analysed by Wilcoxon signed-rank test, while differences between BrS patients and 60 age-sex-matched normal controls were analysed by the Mann-Whitney test. In BrS patients, baseline QRS and QTc durations were longer and normalized after EPI-AS-ATC (151 ± 15 vs. 102 ± 13 ms, P < 0.001; 454 ± 40 vs. 421 ± 27 ms, P < 0.000). Baseline QRS amplitude was lower and increased at late FU (0.63 ± 0.26 vs. 0.84 ± 13 ms, P < 0.000), while Terminal-QRS amplitude decreased (0.24 ± 0.07 vs. 0.08 ± 0.03 ms, P < 0.000). At baseline, CineECG depolarization/repolarization wavefront prevalently localized in RV/RVOT (Terminal-QRS, 57%; ST-Tpeak, 100%; and Tpeak-Tend, 61%), congruent with the AS area on epi-PDM. Early after EPI-AS-RFA, RV/RVOT localization during depolarization disappeared, as Terminal-QRS prevalently localized in the left ventricle (LV, 76%), while repolarization still localized on RV/RVOT [ST-Tpeak (44%) and Tpeak-Tend (98%)]. At late FU, depolarization/repolarization forces prevalently localized in the LV (Terminal-QRS, 94%; ST-Tpeak, 63%; Tpeak-Tend, 86%), like normal controls.

Conclusion

CineECG and 12-lead ECG showed a complex temporo-spatial perturbation of both depolarization and repolarization in BrS patients, prevalently localized in RV/RVOT, progressively normalizing after epicardial ablation.

Can specific ECG markers identify a pharmacologically induced type 1 Brugada pattern? Insights from a large, single-center cohort

BACKGROUND

In patients with a type 2 or 3 Brugada pattern, the pharmacological (IC drugs) induction of a type 1 pattern confirms the diagnosis of Brugada syndrome.

OBJECTIVE

To evaluate the value of various ECG markers in predicting IC drug test results.

METHODS

We retrospectively analysed 443 consecutive patients referred to our Center (from January 2010 to December 2019) to undergo Ajmaline/Flecainide testing; all had a type 2 or 3 Brugada pattern or were relatives with Brugada syndrome. Clinical parameters and ECG markers (r1V1 and SV6 duration and amplitude, QRSV1/QRSV6 duration, V1 and V2 ST amplitude) were independently evaluated for their association to pharmacological test positivity, and a logistic regression model was applied.

RESULTS

The drug test was positive in 151 (34%) patients. On multivariate logistic regression analysis, age > 45 years, female gender, HR >60 bpm, QRSV1/QRSV6 duration >1 and non-isoelectric pattern in V2 were associated with a positive test. The percentage of patients who tested positive increased according to the presence of the above ECG markers (from 11.3% in the absence to 57.6% in the presence of both factors). During long-term follow-up, the clinical event rate was higher in patients with predictive ECG markers and very low in those without.

CONCLUSIONS

In our population we confirmed the ability of QRSV1/QRSV6 duration >1 and of a non-isoelectric pattern in V2 to predict a pharmacologically induced type 1 Brugada pattern. Patients with neither of these ECG markers had a rather low event rate during follow-up.

Deep learning unmasks the ECG signature of Brugada syndrome

One in 10 cases of sudden cardiac death strikes without warning as the result of an inherited arrhythmic cardiomyopathy, such as Brugada Syndrome (BrS). Normal physiological variations often obscure visible signs of this and related life-threatening channelopathies in conventional electrocardiograms (ECGs). Sodium channel blockers can reveal previously hidden diagnostic ECG features, however, their use carries the risk of life-threatening proarrhythmic side effects. The absence of a nonintrusive test places a grossly underestimated fraction of the population at risk of SCD. Here, we present a machine-learning algorithm that extracts, aligns, and classifies ECG waveforms for the presence of BrS. This protocol, which succeeds without the use of a sodium channel blocker (88.4% accuracy, 0.934 AUC in validation), can aid clinicians in identifying the presence of this potentially life-threatening heart disease.

The r'-Wave Algorithm: A New Diagnostic Tool to Predict the Diagnosis of Brugada Syndrome after a Sodium Channel Blocker Provocation Test

A diagnosis of Brugada syndrome (BrS) is based on the presence of a type 1 electrocardiogram (ECG) pattern, either spontaneously or after a Sodium Channel Blocker Provocation Test (SCBPT). Several ECG criteria have been evaluated as predictors of a positive SCBPT, such as the β-angle, the α-angle, the duration of the base of the triangle at 5 mm from the r'-wave (DBT- 5 mm), the duration of the base of the triangle at the isoelectric line (DBT- iso), and the triangle base/height ratio. The aim of our study was to test all previously proposed ECG criteria in a large cohort study and to evaluate an r'-wave algorithm for predicting a BrS diagnosis after an SCBPT. We enrolled all patients who consecutively underwent SCBPT using flecainide from January 2010 to December 2015 in the test cohort and from January 2016 to December 2021 in the validation cohort. We included the ECG criteria with the best diagnostic accuracy in relation to the test cohort in the development of the r'-wave algorithm (β-angle, α-angle, DBT- 5 mm, and DBT- iso.) Of the total of 395 patients enrolled, 72.4% were male and the average age was 44.7 ± 13.5 years. Following the SCBPTs, 24.1% of patients (n = 95) were positive and 75.9% (n = 300) were negative. ROC analysis of the validation cohort showed that the AUC of the r'-wave algorithm (AUC: 0.92; CI 0.85-0.99) was significantly better than the AUC of the β-angle (AUC: 0.82; 95% CI 0.71-0.92), the α-angle (AUC: 0.77; 95% CI 0.66-0.90), the DBT- 5 mm (AUC: 0.75; 95% CI 0.64-0.87), the DBT- iso (AUC: 0.79; 95% CI 0.67-0.91), and the triangle base/height (AUC: 0.61; 95% CI 0.48-0.75) (p < 0.001), making it the best predictor of a BrS diagnosis after an SCBPT. The r'-wave algorithm with a cut-off value of ≥2 showed a sensitivity of 90% and a specificity of 83%. In our study, the r'-wave algorithm was proved to have the best diagnostic accuracy, compared with single electrocardiographic criteria, in predicting the diagnosis of BrS after provocative testing with flecainide.

Brugada Phenocopy Caused by Intracranial Hemorrhage

Brugada syndrome (BrS) is a congenital channelopathy associated with an increased risk of malignant ventricular arrhythmias and sudden cardiac death in individuals without any structural cardiopathy. Brugada phenocopies (BrPs) are clinical entities that present electrocardiographic patterns similar to those of BrS that are elicited only under transitory pathophysiological conditions, with normalization of the ECG pattern after the resolution of those conditions. We present a rare case of BrP due to intracranial hemorrhage. We also present and discuss the diagnostic criteria for BrPs and their application to this case.

Defining electrocardiographic criteria to differentiate non-type 1 Brugada ECG variants from normal incomplete RBBB patterns in the young SCD-SOS cohort

INTRODUCTION

We assessed the prevalence of non-type 1 Brugada pattern (T1BrP) in children and young adults from the Sudden Cardiac Death-Screening Of risk factorS cohort and the diagnostic yield of nonexpert manual and automatic algorithm electrocardiogram (ECG) measurements.

METHODS

Cross-sectional study. We reviewed 14 662 ECGs and identified 2226 with a rSr'-pattern in V1-V2. Among these, 115 were classified by experts in hereditary arrhythmic-syndromes as having or not non-T1BrP, and were compared with measurements of 5 ECG-derived parameters based on a triangle formed by r' -wave (d(A), d(B), d(B)/h, β-angle) and ST-ascent, assessed both automatically and manually by nonexperts. We estimated intra- and interobserver concordance for each criterion, calculated diagnostic accuracy and defined the most appropriate cut-off values.

RESULTS

A rSr'-pattern in V1-V2 was associated with higher PQ interval and QRS duration, male gender, and lower body mass index (BMI). The manual measurements of non-T1BrP criteria were moderately reproducible with high intraobserver and moderate interobserver concordance coefficients (ICC: 0.72-0.98, and 0.63-0.76). Criteria with higher discriminatory capacity were: distance d(B) (0.72; 95% confidence interval [CI]: 0.65-0.80) and ST-ascent (0.87; 95% CI: 0.82-0.92), which was superior to the 4 r'-wave criteria together (area under curve [AUC: 0.74]). We suggest new cut-offs with improved combination of sensitivity and specificity: d(B) ≥ 1.4 mm and ST-ascent ≥ 0.7 mm (sensitivity: 1%-82%; specificity: 71%-84%), that can be automatically measured to allow classification in four morphologies with increasing non-T1BrP probability.

CONCLUSION

rSr'-pattern in precordial leads V1-V2 is a frequent finding and the detection of non-T1BrP by using the aforementioned five measurements is reproducible and accurate. In this study, we describe new cut-off values that may help untrained clinicians to identify young individuals who may require further work-up for a potential Brugada Syndrome diagnosis.

Association of atrial septal defect and Brugada syndrome in a young woman

We report a 25-year-old woman who was diagnosed with atrial septal defect (ASD). An ECG showed only first-degree atrioventricular block and incomplete right bundle branch block. One day after the percutaneous ASD closure, she had a slight fever and an ECG showed a type 1 Brugada pattern. ECG characteristics of ASD are similar to those of a Brugada ECG. This case is rare combination of Brugada syndrome with ASD.

Exercise in the Genetic Arrhythmia Syndromes - A Review

Provide a brief summary of your article (100-150 words; no references or figures/tables). The synopsis appears only in the table of contents and is often used by indexing services such as PubMed. Genetic arrhythmia syndromes are rare, yet harbor the potential for highly consequential, often unpredictable arrhythmias or sudden death events. There has been historical uncertainty regarding the correct advice to offer to affected patients who are reasonably wanting to participate in sporting and athletic endeavors. In some cases, this had led to abundantly cautious disqualifications, depriving individuals from participation unnecessarily. Societal guidance and expert opinion has evolved significantly over the last decade or 2, along with our understanding of the genetics and natural history of these conditions, and the emphasis has switched toward shared decision making with respect to the decision to participate or not, with patients and families becoming better informed, and willing participants in the decision making process. This review aims to give a brief update of the salient issues for the busy physician concerning these syndromes and to provide a framework for approaching their management in the otherwise aspirational or keen sports participant.

The "rSr' ECG pattern" is not always a Brugada ECG pattern

The differential diagnosis of an rSr' pattern in leads V1-V2 on the surface ECG is a common issue in daily practice. This article is protected by copyright. All rights reserved.

Plasma MicroRNAs as noninvasive diagnostic biomarkers in patients with Brugada syndrome

BACKGROUND

Brugada syndrome (BrS) can be diagnosed by a type 1 BrS tracing in a 12-lead electrocardiogram (ECG). However, there are daily variations in the ECGs of BrS patients, which presents a challenge when diagnosing BrS. Although many susceptibility genes have been identified, the SCN5A gene is reportedly the main causative gene of BrS. However, most patients do not have an evidence of genetic predisposition to develop BrS. In addition, the diagnosis and risk stratification for ventricular fibrillation (VF) in patients with BrS presents some problems. Meanwhile, circulating micro RNAs (miRNAs) have drawn increased attention as potential biomarkers of various diseases. We hypothesize that circulating miRNAs may be potential diagnostic biomarkers for BrS.

METHODS

We enrolled 70 Japanese BrS patients and 34 controls for the screening cohort. A total of 2,555 miRNA sequences were detected using the 3D-Gene miRNAs labeling kit and 3D-Gene Human miRNAs Oligo Chip. We compared the expression of the miRNAs between the BrS patients and the controls. We validated whether the miRNA were significantly up- or downregulated in the screening cohort using RT-PCR. We also enrolled 72 Japanese BrS patients and 56 controls to replicate these miRNAs.

RESULTS

Eight miRNAs (hsa-miR-223-3p, hsa-miR-22-3p, hsa-miR-221-3p, hsa-miR-4485-5p, hsa-miR-550a-5p, hsa-miR-423-3p, hsa-miR-23a-3p, and hsa-miR-30d-5p) were downregulated, and one miRNA (hsa-miR-873-3p) was upregulated by more than 3-fold in BrS patients. The multivariate logistic regression analysis determined that hsa-miR-423-3p, hsa-miR-223-3p, and hsa-miR-23a-3p were independently associated with BrS (P < 0.0001). The AUC based on cross validation was 0.871 with a sensitivity and specificity of 83.5% and 81.1%, respectively.

CONCLUSIONS

The plasma miRNAs are potential noninvasive biomarkers of BrS, and the constructed logistic model was useful for discriminating BrS.

The β-angle can help guide clinical decisions in the diagnostic work-up of patients suspected of Brugada syndrome: a validation study of the β-angle in determining the outcome of a sodium channel provocation test

AIMS

In patients with Brugada syndrome (BrS) but without spontaneous Type-1 electrocardiogram, several electrocardiographic characteristics have been studied, including the β-angle. Previous studies suggested that the β-angle might be useful in distinguishing BrS-patients from patients with only suggestive repolarization patterns without performing sodium channel blocker provocation testing. In this study, we aimed to determine the diagnostic value of the β-angle in patients suspected of BrS.

METHODS AND RESULTS

A large cohort (n = 1430) of consecutive patients who underwent provocation testing was evaluated. β-angles were measured in leads V1, V2, and their corresponding positions over the second and third intercostal space. Receiver-operating characteristic curves were constructed and the diagnostic accuracy of previously reported β-angle cut-offs were calculated and evaluated. The importance of the β-angle for predicting the provocation test outcome was determined using a prediction model constructed with logistic regression. The optimum β-angle cut-off in our cohort for ruling out a positive provocation test was 15°; sensitivities were 80-98% and negative predictive values were 79-96% among the right precordial leads. Previously reported β-angle cut-offs performed less well, indicated by lower Youden indices. In the optimism-corrected prediction model [C-statistic: 0.78 (95% CI: 0.75-0.81)], the β-angle had large value (Z-score: 2.1-10.3) and aided construction of a nomogram to predict test outcome.

CONCLUSION

To predict the outcome of provocation testing for BrS, the β-angle alone does not demonstrate strong diagnostic characteristics. However, the β-angle is an important variable to predict provocation test outcome and thus has added value.

ECG in an Athlete With Syncope: Innocuous Incomplete Right Bundle Branch Block or Brugada Pattern?

Abnormalities of an athlete's electrocardiogram may be the result of an underlying heart disease and may carry a risk of sudden death. It is important that electrocardiographic abnormalities are correctly distinguished. We present the case of a young marathon athlete presenting with syncope and incomplete right bundle block pattern suggestive of a type 2 Brugada pattern. (Level of Difficulty: Advanced.).

Novel CineECG enables anatomical 3D localization and classification of bundle branch blocks

AIMS

Ventricular conduction disorders can induce arrhythmias and impair cardiac function. Bundle branch blocks (BBBs) are diagnosed by 12-lead electrocardiogram (ECG), but discrimination between BBBs and normal tracings can be challenging. CineECG computes the temporo-spatial trajectory of activation waveforms in a 3D heart model from 12-lead ECGs. Recently, in Brugada patients, CineECG has localized the terminal components of ventricular depolarization to right ventricle outflow tract (RVOT), coincident with arrhythmogenic substrate localization detected by epicardial electro-anatomical maps. This abnormality was not found in normal or right BBB (RBBB) patients. This study aimed at exploring whether CineECG can improve the discrimination between left BBB (LBBB)/RBBB, and incomplete RBBB (iRBBB).

METHODS AND RESULTS

We utilized 500 12-lead ECGs from the online Physionet-XL-PTB-Diagnostic ECG Database with a certified ECG diagnosis. The mean temporo-spatial isochrone trajectory was calculated and projected into the anatomical 3D heart model. We established five CineECG classes: 'Normal', 'iRBBB', 'RBBB', 'LBBB', and 'Undetermined', to which each tracing was allocated. We determined the accuracy of CineECG classification with the gold standard diagnosis. A total of 391 ECGs were analysed (9 ECGs were excluded for noise) and 240/266 were correctly classified as 'normal', 14/17 as 'iRBBB', 55/55 as 'RBBB', 51/51 as 'LBBB', and 31 as 'undetermined'. The terminal mean temporal spatial isochrone contained most information about the BBB localization.

CONCLUSION

CineECG provided the anatomical localization of different BBBs and accurately differentiated between normal, LBBB and RBBB, and iRBBB. CineECG may aid clinical diagnostic work-up, potentially contributing to the difficult discrimination between normal, iRBBB, and Brugada patients.

Prevalence and Clinical Significance of Latent Brugada Syndrome in Atrial Fibrillation Patients Below 45 Years of Age

Aim: This study aims to describe prevalence and clinical significance of latent Brugada syndrome (BrS) in a young population with atrial fibrillation (AF).

Methods: Between September 2015 and November 2017, among 111 AF patients below 45 years of age, those without pre-existing pathologies and/or known risk factors were selected for the study. Based on baseline 12-lead−24-h Holter electrocardiogram (ECG), previous class 1C antiarrhythmic drug therapy, or ajmaline testing, patients were stratified as latent type 1 BrS or not.

Results: Within the 78 enrolled patients, 13 (16.7%; group 1) revealed a type 1 BrS ECG pattern, while 65 (83.3%; group 2) did not. Mean age was 37 ± 8 vs. 35 ± 7 (p = 0.42), and males were 7 (54%) vs. 54 (83%) (p = 0.02) in the two groups, respectively. Family history of BrS was significantly more common within group 1 patients (2, 15% vs. 0; p = 0.03), and 4 (31%) patients experienced syncope in group 1 vs. 5 (8%) in group 2 (p = 0.02). After a mean follow-up of 42 ± 18 months from the index AF event, more than 80% of the patients, in both study groups, were in sinus rhythm.

Conclusion: In young patients with AF without pre-existing pathologies and/or known risk factors, latent BrS should be suspected. Syncope and a family history of BrS emerge as easily identifiable factors related to BrS. Long-term sinus rhythm maintenance appears satisfactory, either in the presence or not of BrS.

Novel CineECG Derived From Standard 12-Lead ECG Enables Right Ventricle Outflow Tract Localization of Electrical Substrate in Patients With Brugada Syndrome

Background:

In Brugada syndrome (BrS), diagnosed in presence of a spontaneous or ajmaline-induced type-1 pattern, ventricular arrhythmias originate from the right ventricle outflow tract (RVOT). We developed a novel CineECG method, obtained by inverse electrocardiogram (ECG) from standard 12-lead ECG, to localize the electrical activity pathway in patients with BrS.

Methods:

The CineECG enabled the temporospatial localization of the ECG waveforms, deriving the mean temporospatial isochrone from standard 12-lead ECG. The study sample included (1) 15 patients with spontaneous type-1 Brugada pattern, and (2) 18 patients with ajmaline-induced BrS (at baseline and after ajmaline), in whom epicardial potential duration maps were available; (3) 17 type-3 BrS pattern patients not showing type-1 BrS pattern after ajmaline (ajmaline-negative); (4) 47 normal subjects; (5) 18 patients with right bundle branch block (RBBB). According to CineECG algorithm, each ECG was classified as Normal, Brugada, RBBB, or Undetermined.

Results:

In patients with spontaneous or ajmaline-induced BrS, CineECG localized the terminal mean temporospatial isochrone forces in the RVOT, congruent with the arrhythmogenic substrate location detected by epicardial potential duration maps. The RVOT location was never observed in normal, RBBB, or ajmaline-negative patients. In most patients with ajmaline-induced BrS (78%), the RVOT location was already evident at baseline. The CineECG classified all normal subjects and ajmaline-negative patients at baseline as Normal or Undetermined, all patients with RBBB as RBBB, whereas all patients with spontaneous and ajmaline-induced BrS as Brugada. Compared with standard 12-lead ECG, CineECG at baseline had a 100% positive predictive value and 81% negative predictive value in predicting ajmaline test results.

Conclusions:

In patients with spontaneous and ajmaline-induced BrS, the CineECG localized the late QRS activity in the RVOT, a phenomenon never observed in normal, RBBB, or ajmaline-negative patients. The possibility to identify the RVOT as the location of the arrhythmogenic substrate by the noninvasive CineECG, based on the standard 12-lead ECG, opens new prospective for diagnosing patients with BrS.

Fever-Induced Brugada-Pattern Electrocardiogram

BACKGROUND

Brugada syndrome is an increasingly recognized syndrome characterized by a particular electrocardiography (ECG) pattern and clinical criteria and has a high incidence of sudden death in patients with structurally normal hearts. The Brugada ECG pattern can be unmasked by drugs, ischemia, and fever.

CASE REPORT

We present the case of a 47-year-old man who presented to the emergency department with flu-like symptoms and syncope. On arrival, he was febrile and his ECG showed a Brugada pattern. Although this pattern resolved once his fever resolved, the cardiologists were concerned that his syncopal episode might have been due to ventricular tachycardia/fibrillation, and the patient was admitted for implantable cardiac defibrillator placement. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Fever and other stressors can unmask a Brugada pattern on ECG, and if patients have concerning clinical criteria, they should receive emergent cardiology follow-up.

Young athletes' ECG: Incomplete right bundle branch block vs crista supraventricularis pattern

BACKGROUND

Incomplete right bundle branch block (IRBBB) is prevalent among athletes, but its etiology remains to be clearly elucidated and the commonly advocated mechanism, an intraventricular conduction delay, does not explain all cases. In the general population, an apparently similar phenomenon but with different pathophysiology and potential consequences, "crista supraventricularis pattern" (CSP, defined as QRS ≤ 100 ms, S wave <40 ms in I or V6 together with an RSR´ pattern in lead-V1) has been described. Yet, this manifestation has not been studied in athletes. Given that IRBBB can be associated with some serious conditions (including Brugada syndrome, arrhythmogenic cardiomyopathy, or atrial septal defects) the differentiation between IRBB and CSP could enhance the accuracy of the pre-participation screening (PPS). We thus aimed to determine the prevalence of CSP in young athletes.

METHODS

Observational study of standard 12-lead resting ECG in a cohort of children (5-16 years) attending a PPS program (August 2018-May 2019).

RESULTS

6,401 children (mean ± SD age 11.2 ± 2.9 years, 99.2% Caucasian, 93.8% male, 97.2% soccer players) were studied. We found CSP in 850 participants (prevalence = 13.3% [95% confidence interval 12.5-14.1]) whereas 553 (8.6%) had IRBBB. The proportion of athletes showing an S1S2S3 pattern was higher in those with CSP compared with the other QRS morphologies (P < .05).

CONCLUSIONS

CSP might have been overlooked in previous reports of sports PPS for children and misdiagnosed as IRBBB, as the proportion of the former condition was higher. Our findings might add useful information to improve the interpretation of the young athletes' ECG and thus the diagnostic value of PPS.

Diagnosis of type 2 Brugada pattern: insights from a pilot survey

BACKGROUND

Differentiation of Type 2 Brugada Pattern (BP) from incomplete right bundle branch block or normal rSr' pattern can be insidious. The aim of this study was to assess interobserver and intraobserver agreement in the diagnosis of type 2 BP in a cohort of cardiologists with different skills.

METHODS

We collected 14 ECGs with a positive terminal deflection of the QRS complex in lead V1 and V2 at the 4^th intercostal space. We proposed these ECGs, specifying to use 2012 Consensus conference criteria for diagnosis of type 2 BP, to 42 participants: 14 arrhythmologists, 14 general cardiologists and 14 electrophysiology (EP) fellows. The same 14 ECGs, with a different order, were proposed fifteen days later to the same cohort to assess intraobserver variability. Authors analyzed all 14 ECGs in order to assess whether 2012 Consensus Conference criteria for BP were fulfilled. All patients underwent provocative test with IC antiarrhythmics drugs (flecainide) in order to exclude or confirm the diagnosis of Brugada Syndrome (BrS).

RESULTS

Slight interobserver agreement (Fleiss K<0.20) in the diagnosis of type 2 BP was observed in all three categories of cardiologists. Considering five operators per class, intraobserver agreement is variable (k ranging from 0.000 to 0.857), with a slight superiority of arrhytmologists (k minimum value 0.276; k maximum value 0.857).

CONCLUSIONS

This study demonstrated, for the first time, a low interobserver agreement in diagnosis of type 2 BP in categories of cardiologists with different abilities. Reproducibility of type 2 BP diagnosis (intraobserver agreement) is poor, even among experts. These findings highlight the difficulties in analysis of ECG with BrS suspicion and, therefore, underscore the key role of clinical and anamnestic data.

[Brugada syndrome : Risk stratification and prevention of sudden cardiac death]

Brugada syndrome is ion channelopathy defined by coved type ST-elevation in at least one right precordial ECG lead. Patients may suffer from ventricular tachycardia/fibrillation, which may cause syncope or sudden cardiac death. The majority of patients are likely to remain asymptomatic throughout life. A correct ECG diagnosis remains challenging. The implantable cardioverter/defibrillator (ICD) is the only established therapy to protect against sudden cardiac death. Thus, individual risk stratification is of major clinical relevance in primary prevention. The present article gives an update on current risk stratification and novel therapeutic options apart from ICD therapy.

Present Status of Brugada Syndrome: JACC State-of-the-Art Review

The Brugada syndrome is an inherited disorder associated with risk of ventricular fibrillation and sudden cardiac death in a structurally normal heart. Diagnosis is based on a characteristic electrocardiographic pattern (coved type ST-segment elevation ≥2 mm followed by a negative T-wave in ≥1 of the right precordial leads V₁ to V₂), observed either spontaneously or during a sodium-channel blocker test. The prevalence varies among regions and ethnicities, affecting mostly males. The risk stratification and management of patients, principally asymptomatic, still remains challenging. The current main therapy is an implantable cardioverter-defibrillator, but radiofrequency catheter ablation has been recently reported as an effective new treatment. Since its first description in 1992, continuous achievements have expanded our understanding of the genetics basis and electrophysiological mechanisms underlying the disease. Currently, despite several genes identified, SCN5A has attracted most attention, and in approximately 30% of patients, a genetic variant may be implicated in causation after a comprehensive analysis.

Sudden Cardiac Death: Who Is at Risk?

Sudden cardiac death (SCD) is a leading cause of death in the United States. Despite improvements in therapy, the incidence of SCD as a proportion of overall cardiovascular death remains relatively unchanged. This article aims to answer the question, "Who is at risk for SCD?" In the process, it reviews the definition, pathophysiology, epidemiology, and risk factors of SCD. Patients at risk for SCD and appropriate treatment strategies are discussed.

Brugada Syndrome: Progress in Diagnosis and Management

Brugada syndrome (BrS) represents an inherited disorder associated with risk of sudden cardiac death due to VF in patients without structural heart disease. Currently, BrS is diagnosed by typical cove-shaped ST-segment elevation >2 mm in >1 RV precordial lead V1, V2 occurring spontaneously or after a sodium-channel blocker provocation test without any further evidence of malignant arrhythmias. An ICD should always be implanted in symptomatic BrS patients to prevent sudden death, despite high rates of complications with these devices. In asymptomatic people, an electrophysiological study should be performed to evaluate the need for an ICD. The recent discovery of a functional substrate has revolutionised our approach to the pathophysiology and management of BrS. Promising new therapeutic options have emerged in the last 3 years. Ajmaline is able to determine the extension of the substrate by prolonging the duration and fragmentation of abnormal epicardial electrograms. Substrate ablation results in the disappearance of both coved-type ECG and ventricular tachycardia/VF inducibility. These findings are clinically relevant, suggesting that epicardial ablation guided by ajmaline infusion may be an effective therapeutic option in BrS, potentially removing the need for ICD implantation.

A three-dimensional computed model of ST segment abnormality in type 1 Brugada Pattern: A key role of right ventricular outflow tract orientation?

Since its first description, Brugada Syndrome is characterized by definite ECG abnormalities (J wave, elevated ST segment) confined in right precordial leads. Brugada Pattern (BP) could be found in one or more right precordial leads, at conventional or higher intercostal spaces. A recent study, conducted by our group, reported that slightly less than one half of patients with type 1 BP show a definite ST segment depression (≥0.1 mV with duration ≥ 0.08 s) in the inferior leads. With these premises, 4 distinct ST abnormalities phenotypes can be recognizable in Type 1 BP. We speculated the key role of orientation of right ventricular outflow tract in the thorax, particularly the inclination of anterior wall compared to the sternum, contributing to the determination of these various ECG phenotypes. An interactive program, ECGsim, able to simulate ECG appearance in several anatomical and electrical models, confirmed this assumption. This computed model affirmed the strict relationship between ST segment depression in the inferior leads and the ST segment elevation in right precordial leads, typical of type 1 BP. A horizontal right ventricular outflow tract, in fact, gives raise to abnormal BP vector directed both superiorly and anteriorly, explaining, at the same time, typical BP appearance in right precordial leads and ST segment depression in the inferior leads.

The S-wave angle identifies arrhythmogenic right ventricular cardiomyopathy in patients with electrocardiographically concealed disease phenotype

BACKGROUND

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) carries risk of sudden death. We hypothesize that the S-wave angle differentiates ARVD/C with otherwise normal electrocardiograms from controls.

MATERIALS AND METHODS

All patients met Task Force 2010 definite ARVD/C criteria. ARVD/C patients without Task Force depolarization/repolarization criteria (-ECG) were compared to controls. Electrocardiogram measures of QRS duration, corrected QT interval, and measured angle between the upslope and downslope of the S-wave in V2, were assessed.

RESULTS

Definite ARVD/C was present in 155 patients (42.7 ± 17.3 years, 68.4%male). -ECG ARVD/C patients (66 patients) were compared to 66 control patients (41.8 ± 17.6 years, 65.2%male). Only the S-wave angle differentiated -ECG ARVD/C patients from controls (<0.001) with AU the ROC curve of 0.77 (95%CI 0.53 to 0.71) and odds ratio of 28.3 (95%CI 6.4 to 125.5).

CONCLUSION

ARVD/C may lead to development of subtle ECG abnormalities distinguishable using the S-wave angle prior to development of 2010 Taskforce ECG criteria.

Comparisons of clinical impacts on individuals with Brugada electrocardiographic patterns defined by ISHNE criteria or EHRA/HRS/APHRS criteria: a nationwide community-based study

INTRODUCTION

Identifying Brugada electrocardiographic pattern (BrP) early is crucial to prevent sudden cardiac death. Two different diagnostic criteria proposed by International Society for Holter and Noninvasive Electrocardiography (ISHNE) and Heart Rhythm Society/European Heart Rhythm Association/Asia-Pacific Heart Rhythm Society (HRS/EHRA/APHRS) were widely used in clinical practice. The difference in prevalence and prognosis of BrP by applying the two different criteria was never studied before.

METHODS

This study was prospectively conducted in a nationwide large-scale stratified random sampling community-based cohort (HALST) from Han Chinese population in Taiwan from December 2008 to December 2012. We compared the prevalence and prognosis of BrP defined by the two diagnostic criteria.

RESULTS

A total of 5214 adults were enrolled (2530 men) with mean age of 69.3 years. Four had spontaneous type 1 BrP (0.077%). By the HRS/EHRA/APHRS criteria, 68 individuals have type 2 BrP (1.30%) and 101 have type 3 BrP (1.94%) whereas by the ISHNE criteria, 46 individuals exhibited type 2 BrP (0.88%). When applying the ISHNE criteria, the number of individuals with BrP decreased by 71%. However, all-cause mortality and cardiovascular mortality were not different between individuals with or without BrP, irrespective of the criteria used.

CONCLUSIONS

The two different criteria may impact the diagnostic yield of individuals with BrP, but do not affect the prognosis of the individuals with BrP. Key messages Comparing with the use of HRS/EHRA/APHRS criteria, the number of individuals with Brugada ECG patterns was decreased by 71% when applying the ISHNE criteria. The prognosis of individuals with Brugada ECG patterns defined by 2012 ISHNE or 2013 HRS/EHRA/APHRS criteria were not different.

Masquerading bundle branch block obscuring the diagnosis of Brugada syndrome: an electrocardiographic and vectorcardiographic study

We describe the induction of a masquerading bundle branch block in two patients with Brugada syndrome following the administration of Ajmaline. The development of this conduction disturbance prevented the correct electrocardiographic diagnosis. However, the simultaneously obtained vectocardiogram identified both the Brugada pattern and the masquerading bundle branch block.

Evaluation of baseline ECG in patients undergoing Oral Flecainide Challenge test for suspected Brugada Syndrome: An analysis of lead II

Background and Objectives

We analyzed Lead II in patients undergoing an Oral Flecainide Challenge test (FCT), to identify any pointers that could predict a positive FCT and thereby help in recognition of latent BS.

Methods

The following parameters in lead II were retrospectively analyzed from the pre-test ECG in 62 patients undergoing FCT for suspected BS: The presence or absence of S waves, S wave amplitude, duration and upslope duration; J point parameters- Early repolarization, QRS notch, and QRS Slur; ST segment parameters-lack of isoelectric ST segment, ST duration and QT interval.

Results

48 had positive FCT (Group-1) while 14 were negative for FCT(Group-2). Lack of an isoelectric ST segment (50% vs 14.29%, p = 0.018) and slurring of QRS (33.33% vs 0%, p = 0.014) was more common in Group-1 than Group-2. Group-1 had shorter ST segment duration (median 81.5 (IQR 64–103.5) vs 110 (IQR 90–132), p = 0.002) and shorter ST: QT ratio (median 0.28 (IQR 0.22–0.35) vs 0.23 (0.18–0.27), p = 0.007). QRS notch/depressed J point (87.5%), QRS slur (100%), and lack of isoelectric ST segment (92.31%) had high sensitivity for predicting an inducible Type 1 Brugada pattern. Combining two parameters- ST: QT ratio<0.24 and lack of isoelectric ST segment-considerably improved the specificity (73.3%), and the positive predictive value of the test to 76%. The results remained accurate when validated in a small prospective cohort.

Conclusion

Shortened ST segment in Lead II, lack of isoelectric ST segment, slurred QRS and ST/QT ratio <0.24 are predictive of underlying Brugada pattern in baseline ECG.

Efficacy and safety of dextrose-insulin in unmasking non-diagnostic Brugada ECG patterns

BACKGROUND

Typical diagnostic, coved-type 1, Brugada ECG patterns fluctuate spontaneously over time with a high proportion of non-diagnostic ECG patterns. Insulin modulates ion transport mechanisms and causes hyperpolarization of the resting potential. We report our experience with unmasking J-ST changes in response to a dextrose-insulin test.

METHODS

Nine patients, mean age 40.5±19.4years (range: 15-65years), presented initially with a non-diagnostic ECG pattern, which was suggestive of Brugada syndrome (group I). They were compared with 10 patients with normal ECG patterns (group II). Participants received an infusion of 50g of 50% dextrose, followed by 10IU of intravenous regular insulin. Positive changes were defined by conversion to a diagnostic ECG pattern.

RESULTS

The dextrose-insulin test was positive in six of seven (85.7%) patients (kappa 0.79, p=0.02) that was confirmed with a pharmacologic test (kappa 1, p=0.003). One had an inconclusive test, and two with a negative test had an early repolarization ECG pattern. All subjects in group II had a negative test (p<0.01). The maximum changes of the J-ST segment were observed 41.3±31.4minutes (range 3-90minutes) after dextrose-insulin infusion. One patient had monomorphic ventricular bigeminy without spontaneous or induced ventricular fibrillation.

CONCLUSION

Changes in J-ST segment in the Brugada syndrome are influenced by glucose-insulin, and this report reproduces and supports the efficacy and safety of this metabolic test in the differential diagnosis of patients with non-diagnostic ECG patterns.

Spatiotemporal Characteristics of QRS Complexes Enable the Diagnosis of Brugada Syndrome Regardless of the Appearance of a Type 1 ECG

INTRODUCTION

The diagnosis of Brugada syndrome based on the ECG is hampered by the dynamic nature of its ECG manifestations. Brugada syndrome patients are only 25% likely to present a type 1 ECG. The objective of this study is to provide an ECG diagnostic criterion for Brugada syndrome patients that can be applied consistently even in the absence of a type 1 ECG.

METHODS AND RESULTS

We recorded 67-lead body surface potential maps from 94 Brugada syndrome patients and 82 controls (including right bundle branch block patients and healthy individuals). The spatial propagation direction during the last r' wave and the slope at the end of the QRS complex were measured and compared between patients groups. Receiver-operating characteristic curves were constructed for half of the database to identify optimal cutoff values; sensitivity and specificity for these cutoff values were measured in the other half of the database. A spontaneous type 1 ECG was present in only 30% of BrS patients. An orientation in the sagittal plane < 101º during the last r' wave and a descending slope < 9.65 mV/s enables the diagnosis of the syndrome with a sensitivity of 69% and a specificity of 97% in non-type 1 Brugada syndrome patients.

CONCLUSION

Spatiotemporal characteristics of surface ECG recordings can enable a robust identification of BrS even without the presence of a type 1 ECG.

Brugada Syndrome: Clinical, Genetic, Molecular, Cellular, and Ionic Aspects

Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome first described as a new clinical entity in 1992. Electrocardiographically characterized by distinct coved type ST segment elevation in the right-precordial leads, the syndrome is associated with a high risk for sudden cardiac death in young adults, and less frequently in infants and children. The electrocardiographic manifestations of BrS are often concealed and may be unmasked or aggravated by sodium channel blockers, a febrile state, vagotonic agents, as well as by tricyclic and tetracyclic antidepressants. An implantable cardioverter defibrillator is the most widely accepted approach to therapy. Pharmacologic therapy is designed to produce an inward shift in the balance of currents active during the early phases of the right ventricular action potential (AP) and can be used to abort electrical storms or as an adjunct or alternative to device therapy when use of an implantable cardioverter defibrillator is not possible. Isoproterenol, cilostazol, and milrinone boost calcium channel current and drugs like quinidine, bepridil, and the Chinese herb extract Wenxin Keli inhibit the transient outward current, acting to diminish the AP notch and thus to suppress the substrate and trigger for ventricular tachycardia or fibrillation. Radiofrequency ablation of the right ventricular outflow tract epicardium of patients with BrS has recently been shown to reduce arrhythmia vulnerability and the electrocardiographic manifestation of the disease, presumably by destroying the cells with more prominent AP notch. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of BrS as well as the approach to therapy.

New methodologies for measuring Brugada ECG patterns cannot differentiate the ECG pattern of Brugada syndrome from Brugada phenocopy

BACKGROUND

Brugada phenocopies (BrP) are clinical entities characterized by ECG patterns that are identical to true Brugada syndrome (BrS), but are elicited by various clinical circumstances. A recent study demonstrated that the patterns of BrP and BrS are indistinguishable under the naked eye, thereby validating the concept that the patterns are identical.

OBJECTIVE

The aim of our study was to determine whether recently developed ECG criteria would allow for discrimination between type-2 BrS ECG pattern and type-2 BrP ECG pattern.

METHODS

Ten ECGs from confirmed BrS (aborted sudden death, transformation into type 1 upon sodium channel blocking test and/or ventricular arrhythmias, positive genetics) cases and 9 ECGs from confirmed BrP were included in the study. Surface 12-lead ECGs were scanned, saved in JPEG format for blind measurement of two values: (i) β-angle; and (ii) the base of the triangle. Cut-off values of ≥58° for the β-angle and ≥4mm for the base of the triangle were used to determine the BrS ECG pattern.

RESULTS

Mean values for the β-angle in leads V1 and V2 were 66.7±25.5 and 55.4±28.1 for BrS and 54.1±26.5 and 43.1±16.1 for BrP respectively (p=NS). Mean values for the base of the triangle in V1 and V2 were 7.5±3.9 and 5.7±3.9 for BrS and 5.6±3.2 and 4.7±2.7 for BrP respectively (p=NS). The β-angle had a sensitivity of 60%, specificity of 78% (LR+ 2.7, LR- 0.5). The base of the triangle had a sensitivity of 80%, specificity of 40% (LR+ 1.4, LR- 0.5).

CONCLUSIONS

New ECG criteria presented relatively low sensitivity and specificity, positive and negative predictive values to discriminate between BrS and BrP ECG patterns, providing further evidence that the two patterns are identical.

Methods for Improving the Diagnosis of a Brugada ECG Pattern

Brugada syndrome (BrS) is an inherited channelopathy that predisposes individuals to malignant arrhythmias and can lead to sudden cardiac death. The condition is characterized by two electrocardiography (ECG) patterns: the type-1 or "coved" ECG and the type-2 or "saddleback" ECG. Although the type-1 Brugada ECG pattern is diagnostic for the condition, the type-2 Brugada ECG pattern requires differential diagnosis from conditions that produce a similar morphology. In this article, we present a case that is suspicious but not diagnostic for BrS and discuss the application of ECG methodologies for increasing or decreasing suspicion for a diagnosis of BrS.

Expert cardiologists cannot distinguish between Brugada phenocopy and Brugada syndrome electrocardiogram patterns

AIMS

Brugada phenocopies (BrPs) are electrocardiogram (ECG) patterns that are identical to true Brugada syndrome (BrS) but are induced by various clinical conditions. The concept that both ECG patterns are visually identical has not been formally demonstrated. The aim of our study was to determine if experts on BrS were able to accurately distinguish between the BrS and BrP ECG patterns.

METHODS AND RESULTS

Six ECGs from confirmed cases of BrS and six ECGs from previously published cases of BrP were included in the study. Surface 12-lead ECGs were scanned, saved in JPEG format, and sent to 10 international experts on BrS for evaluation (no clinical history provided). Evaluators were asked to label each case as a Brugada ECG pattern or non-Brugada ECG pattern by visual interpretation alone. The overall accuracy was 53 ± 33% for all cases. Within the BrS cases, the mean accuracy was 63 ± 34% and within the BrP cases, the mean accuracy was 43 ± 33%. Intra-observer repeatability was moderate (κ = 0.56) and inter-observer agreement was fair (κ = 0.36) while evaluator accuracy vs. the true diagnosis was only marginally better than chance (κ = 0.05). Similarly, diagnostic operating characteristics were poor (sensitivity 62%, specificity 43%, +LR 1.1, -LR 0.9).

CONCLUSION

Our results provide strong evidence that BrP and BrS ECG patterns are visually identical and indistinguishable. These findings support the use of systematic diagnostic criteria for differentiating BrP vs. BrS as an erroneous diagnosis may have a negative impact on patient morbidity and mortality.

Genetics of inherited primary arrhythmia disorders

A sudden unexplained death is felt to be due to a primary arrhythmic disorder when no structural heart disease is found on autopsy, and there is no preceding documentation of heart disease. In these cases, death is presumed to be secondary to a lethal and potentially heritable abnormality of cardiac ion channel function. These channelopathies include congenital long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, Brugada syndrome, and short QT syndrome. In certain cases, genetic testing may have an important role in supporting a diagnosis of a primary arrhythmia disorder, and can also provide prognostic information, but by far the greatest strength of genetic testing lies in the screening of family members, who may be at risk. The purpose of this review is to describe the basic genetic and molecular pathophysiology of the primary inherited arrhythmia disorders, and to outline a rational approach to genetic testing, management, and family screening.

[Brugada ECG]

The Brugada syndrome (BrS) is characterized by a typical electrocardiogram (ECG) pattern of right precordial ST-segment elevation and the cardinal symptoms syncope and sudden cardiac death as clinical correlate of malignant ventricular arrhythmias in young adults without structural heart disease. The diagnosis of a type 1 Brugada-ECG is based on the documentation of a coved-type (≥ 0.2 mV) ST elevation followed by a negative T wave. The use of the ECG criteria postulated in the consensus of 2012 is helpful to distinguish between saddleback-type 2 (or type 3) J point/ST elevation and incomplete right bundle branch block. Spontaneous or drug-induced type 1 ST elevation can frequently only be detected in a single right precordial lead (V1 or V2), occurs sometimes together with a type 2 (or type 3) pattern in one and the same 12-lead ECG and can sometimes only be seen in modified right precordial leads. The ST elevation is less pronounced in females. Spontaneous and exercise-induced type 1 ST elevation, fragmented QRS complex, prolonged PR interval (> 200 ms), QRS prolongation in V2 (≥ 120 ms) and markers of an increased heterogeneity of ventricular repolarization are associated with an increased arrhythmic risk. The occurrence of spontaneous or dynamic type 1 ST elevation, a macroscopic T wave alternans or pronounced inferior (lateral) J point/ST elevation are signs of acute electrical instability.

Characterization of repolarization in Brugada syndrome patients during exercise testing: Dynamic angle evaluation

BACKGROUND

A new ECG criterion has been studied in Brugada syndrome (BrS) at rest to differentiate type 2 and incomplete right bundle branch block (IRBBB).

METHODS

We assessed this criterion during exercise comparing BrS (46 patients) and IRBBB (17 patients). A beta angle was measured from lead V1 between the upslope of S-wave and the downslope of the r'-wave.

RESULTS

Beta angle was significantly larger in BrS at rest (58±24° vs 25±15°, p<0.001), exercise (47±26° vs 15±11°, p<0.001), and recovery (46±24° vs 21±12°, p<0.001) with a reduction in angle at exercise compared to rest. There was a significant rebound in angle at recovery in the control group to (p<0.001); no such rebound was observed in the BrS group (p=NS).

CONCLUSION

Beta angle study at rest and its evolution at exercise could help discriminate BrS patients from healthy subjects.

Novel Therapeutic Strategies for the Management of Ventricular Arrhythmias Associated with the Brugada Syndrome

INTRODUCTION

Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by prominent J waves appearing as distinct coved type ST segment elevation in the right precordial leads of the ECG. It is associated with a high risk for sudden cardiac death.

AREAS COVERED

We discuss 1) ECG manifestations of BrS which can be unmasked or aggravated by sodium channel blockers, febrile states, vagotonic agents, as well as tricyclic and tetracyclic antidepressants; 2) Genetic basis of BrS; 3) Ionic and cellular mechanisms underlying BrS; 4) Therapy involving devices including an implantable cardioverter defibrillator (ICD); 5) Therapy involving radiofrequency ablation; and 6) Therapy involving pharmacological therapy which is aimed at producing an inward shift in the balance of the currents active during phase 1 of the right ventricular action potential either by boosting calcium channel current (isoproterenol, cilostazol and milrinone) or by inhibition of transient outward current Ito (quinidine, bepridil and the Chinese herb extract Wenxin Keli).

EXPERT OPINION

This review provides an overview of the clinical and molecular aspects of BrS with a focus on approaches to therapy. Available data suggest that agents capable of inhibiting the transient outward current Ito can exert an ameliorative effect regardless of the underlying cause.

Brugada ECG patterns in athletes

Brugada syndrome is responsible for up to 4% of all sudden cardiac deaths worldwide and up to 20% of sudden cardiac deaths in patients with structurally normal hearts. Heterogeneity of repolarization and depolarization, particularly over the right ventricle and the outflow tract, is responsible for the arrhythmogenic substrate. The coved Type I ECG pattern is considered diagnostic of the syndrome but its prevalence is very low. Distinguishing between a saddle back Type 2 Brugada pattern and one of many "Brugada-like" patterns presents challenges especially in athletes. A number of criteria have been proposed to assess Brugada ECG patterns. Proper precordial ECG lead placement is paramount. This paper reviews Brugada syndrome, Brugada ECG patterns, and recently proposed criteria. Recommendations for evaluating a Brugada ECG pattern are provided.

Electrocardiographic methods for diagnosis and risk stratification in the Brugada syndrome

The Brugada syndrome (BrS) is a malignant, genetically-determined, arrhythmic syndrome manifesting as syncope or sudden cardiac death (SCD) in individuals with structurally normal hearts. The diagnosis of the BrS is mainly based on the presence of a spontaneous or Na + channel blocker induced characteristic, electrocardiographic (ECG) pattern (type 1 or coved Brugada ECG pattern) typically seen in leads V1 and V2 recorded from the 4th to 2nd intercostal (i.c.) spaces. This pattern needs to be distinguished from similar ECG changes due to other causes (Brugada ECG phenocopies). This review focuses mainly on the ECG-based methods for diagnosis and arrhythmia risk assessment in the BrS. Presently, the main unresolved clinical problem is the identification of those patients at high risk of SCD who need implantable cardioverter-defibrillator (ICD), which is the only therapy with proven efficacy. Current guidelines recommend ICD implantation only in patients with spontaneous type 1 ECG pattern, and either history of aborted cardiac arrest or documented sustained VT (class I), or syncope of arrhythmic origin (class IIa) because they are at high risk of recurrent arrhythmic events (up to 10% or more annually for those with aborted cardiac arrest). The majority of BrS patients are asymptomatic when diagnosed and considered to have low risk (around 0.5% annually) and therefore not indicated for ICD. The majority of SCD victims in the BrS, however, had no symptoms prior to the fatal event and therefore were not protected with an ICD. While some ECG markers such as QRS fragmentation, infero-lateral early repolarisation, and abnormal late potentials on signal-averaged ECG are known to be linked to increased arrhythmic risk, they are not sufficiently sensitive or specific. Potential novel ECG-based strategies for risk stratification are discussed based on computerised methods for depolarisation and repolarisation analysis, a composite approach targeting several major components of ventricular arrhythmogenesis, and the collection of large digital ECG databases in genotyped BrS patients and their relatives.

Prognostic implications of intraventricular conduction delays in a general population: the Health 2000 Survey

AIMS

We examined the prognostic impact of eight different intraventricular conduction delays (IVCD) in the standard electrocardiogram (ECG) in a community cohort.

METHODS AND RESULTS

Data were collected from 6299 Finnish individuals. During a mean 8.2 years (interquartile range 8.1 to 8.3) of follow-up 640 subjects died (10.2%); 277 (4.4%) were cardiovascular deaths. For both sexes, all-cause and cardiovascular mortality was higher in subjects with IVCD than in those without. In Cox regression analysis after adjustment for age and gender, the hazard ratio for cardiovascular mortality for non-specific IVCD was 4.25 (95% confidence interval [CI] 1.95-9.26, P < 0.0001) and for left bundle branch block (LBBB) 2.11 (95% CI 1.31-3.41, P = 0.002). Right bundle branch block (RBBB) was not related to additional mortality, while incomplete RBBB (IRBBB) presented a hazard ratio of 2.24 (95% CI 1.064-4.77, P = 0.036).

CONCLUSIONS

In the general population, non-specific IVCD, LBBB, and IRBBB were associated with increased relative risk for all-cause and cardiovascular mortality. RBBB did not have an impact on cardiovascular mortality either in subjects with or without previous heart disease.