Brugada Syndrome as a Major Cause of Sudden Cardiac Death in Asians

Multiparametric models for predicting major arrhythmic events in Brugada syndrome: a systematic review and critical appraisal

AIMS

Despite several risk models to predict major arrhythmic events (MAE) in Brugada syndrome (BrS) having been developed, reproducibility and methodology remain a concern. Our aim was to assess the quality of model development and validation, and determine the discriminative performance of available models.

METHODS AND RESULTS

Electronic databases (Medline, Embase, and Central) were searched through September/2024 for studies developing or validating multivariable prediction models for MAE in BrS. Methodological quality and risk of bias (RoB) were assessed using the Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS) checklist and the Prediction Model Risk of Bias Assessment (PROBAST) Tool. Pooled random-effects c-statistics were obtained for each model. A total of 16 studies, including 11 unique multivariable scores, were included. All models had domains classified as high RoB. Common sources of bias were inappropriate inclusion/exclusion criteria, predictor selection, low number of events and underreporting of performance measures. Pooled c-statistics among patients without previous MAE showed good performance for Brugada-Risk [AUC 0.81, 95% confidence interval (CI) 0.71-0.91; I2 64%; three studies], fair for PAT (AUC 0.79, 95% CI 0.45-1.12; I2 95%; two studies), Delise (AUC 0.77, 95% CI 0.72-0.81, I2 39%, three studies), and Sieira (AUC 0.73, 95% CI 0.64-0.82; I2 64%; five studies), and moderate for Shanghai (AUC 0.69, 95% CI 0.61-0,76; I2 13%; three studies).

CONCLUSION

Currently available multiparametric models for prediction of MAE in BrS have important shortcomings in model development and inadequate evaluation. Further validation of current models in external cohorts is required before safe transition to clinical practice.

Commotio Cordis: A Comprehensive Review

Commotio cordis is a rare, however, potentially fatal, cardiovascular phenomenon arising from direct chest wall trauma, causing sudden cardiac arrest and potentially death. It is primarily seen in young athletes who participate in contact and organized sports. Though debated, the cause of commotio cordis is believed to involve specific timing of chest impact during ventricular electrical activity leading to severe arrhythmic events. Due to sudden onset, the first step in management is immediate and effective basic life support with automated external defibrillation, followed by advanced cardiac life support. Future considerations should include secondary prevention measures such as protective padding in contact sports. It is paramount that clinicians are vigilant in recognizing potential cases of commotio cordis in the field and provide immediate care. This review consolidates the current understanding of commotio cordis, emphasizing the importance of awareness and early intervention. Future research is warranted, including retrospective and observational studies to identify high-risk patterns or trends associated with the condition.

Entrectinib-Induced Brugada Syndrome Leading to Ventricular Tachycardia in A Patient with ROS1 Fusion-Positive Lung Adenocarcinoma

A 65-year-old male presented to the emergency room after experiencing syncope while driving, causing a self-inflicted accident. He had previously been diagnosed with stage IV A (cTXN2M1a) lung adenocarcinoma with C-ROS oncogene 1 (ROS1) fusion gene, wherein entrectinib (a multikinase inhibitor of ROS1, 600 mg orally once daily) was initiated as the first-line chemotherapy 12 days prior. He presented with haemodynamically unstable conditions without fever (blood pressure 89/42 mmHg; heart rate, 180/min). The 12-lead electrocardiogram revealed ventricular tachycardia (VT) with a left bundle branch block and right axis deviation. Synchronised electrical cardioversion terminated the sustained VT, and the post-electrocardiogram exhibited coved-type ST-segment elevation in V1 to V3. An emergency coronary angiography showed no abnormal findings. Coved-type ST-segment elevation in V1 to V3 persisted for two days following cessation of entrectinib; however, electrocardiogram findings gradually normalised, with no recurrence of clinical VT. Catheter ablation for VT was initially planned; however, the consultant pulmonologist considered that entrectinib could induce Brugada syndrome (BrS), resulting in sustained VT. Therefore, the plan was suspended and entrectinib was discontinued. Electrophysiological examination with programmed electrical and pilsicainide infusion for risk stratification failed to induce clinical VT, and the patient was considered at low risk for VT recurrence following entrectinib discontinuation. Accordingly, we opted for close observation. At the one-year follow-up, no ventricular arrhythmias were noted. The relationship between entrectinib and drug-induced BrS remains unclear, with few reported cases. Continuous or frequent electrocardiogram monitoring during hospitalisation post entrectinib initiation may help detect entrectinib-induced BrS.

LEARNING POINTS

The relationship between entrectinib and drug-induced Brugada syndrome remains unclear, and reports of entrectinib-induced Brugada syndrome are rare.We performed risk stratification using electrophysiological examinations in a case of entrectinib-induced Brugada syndrome in a patient with ROS1 fusion-positive lung adenocarcinoma.Our results suggest that continuous electrocardiogram monitoring or frequent electrocardiogram recording at least once a day several days following entrectinib initiation may help detect entrectinib-induced Brugada syndrome irrespective of being in or out of hospital.

Risk stratification of elderly patients with Brugada syndrome: Results from a large Japanese cohort of idiopathic ventricular fibrillation

Background

Brugada syndrome (BrS) is an inherited cardiac channelopathy associated with a high risk of sudden cardiac death (SCD) due to ventricular fibrillation (VF). Although implantable cardioverter-defibrillators (ICDs) are the primary therapy for SCD prevention, the risk stratification of elderly patients with BrS remains unclear. This study aimed to evaluate the incidence and risk factors of life-threatening arrhythmias in elderly patients with BrS.

Methods

We analyzed 523 patients with BrS (mean age 51 ± 13 years, 497 men) enrolled in the multicenter prospective Japan Idiopathic Ventricular Fibrillation Study. Patients were categorized into the elderly (>60 years, n = 150) and nonelderly (≤60 years, n = 373) groups. Clinical characteristics, programmed electrical stimulation (PES) results, and outcomes, including cardiac events (CEs: VF, fast ventricular tachycardia, or SCD), were compared. Statistical analyses were performed using Kaplan-Meier curves and Cox proportional hazard models.

Results

During a mean follow-up of 106 ± 62 months, 59 patients (11%) experienced CE. The annual CE incidence was lower in the elderly group than in the nonelderly group (0.7% vs. 1.5%, p = 0.016). History of VF independently predicted CE occurrence in elderly patients (hazard ratio: 23.5, p < 0.001). Asymptomatic elderly patients exhibited a negligible risk of CE. PES did not predict CE occurrence in the elderly group.

Conclusions

Elderly patients with BrS have a better prognosis than nonelderly patients, particularly if they are asymptomatic. A history of VF is a key risk factor for life-threatening arrhythmias in elderly patients with BrS.

Identifying genomic variant associated with long QT syndrome type 2 in an ecuadorian mestizo individual: a case report

Introduction

Long QT syndrome (LQTS) is an autosomal dominant inherited cardiac condition characterized by a QT interval prolongation and risk of sudden death. There are 17 subtypes of this syndrome associated with genetic variants in 11 genes. The second most common is type 2, caused by a mutation in the KCNH2 gene, which is part of the potassium channel and influences the final repolarization of the ventricular action potential. This case report presents an Ecuadorian teen with congenital Long QT Syndrome type 2 (OMIM ID: 613688), from a family without cardiac diseases or sudden cardiac death backgrounds.

Case presentation

A 14-year-old girl with syncope, normal echocardiogram, and an irregular electrocardiogram was diagnosed with LQTS. Moreover, by performing Next-Generation Sequencing, a pathogenic variant in the KCNH2 gene p.(Ala614Val) (ClinVar ID: VCV000029777.14) associated with LQTS type 2, and two variants of uncertain significance in the AKAP9 p.(Arg1654GlyfsTer23) (rs779447911), and TTN p. (Arg34653Cys) (ClinVar ID: VCV001475968.4) genes were identified. Furthermore, ancestry analysis showed a mainly Native American proportion.

Conclusion

Based on the genomic results, the patient was identified to have a high-risk profile, and an implantable cardioverter defibrillator was selected as the best treatment option, highlighting the importance of including both the clinical and genomics aspects for an integral diagnosis.

Brugada Syndrome as an Underlying Diagnosis for a Prehospital Seizure Dispatch

Brugada syndrome is an inherited genetic disorder known to cause a variety of patient complaints but may ultimately cause ventricular fibrillation and sudden cardiac death. We present a patient with witnessed seizure who was ultimately diagnosed with Brugada syndrome. Multiple ventricular arrhythmias complicated the case, which was managed in- and out-of-hospital.

Development of automated patch clamp assays to overcome the burden of variants of uncertain significance in inheritable arrhythmia syndromes

Advances in next-generation sequencing have been exceptionally valuable for identifying variants in medically actionable genes. However, for most missense variants there is insufficient evidence to permit definitive classification of variants as benign or pathogenic. To overcome the deluge of Variants of Uncertain Significance, there is an urgent need for high throughput functional assays to assist with the classification of variants. Advances in parallel planar patch clamp technologies has enabled the development of automated high throughput platforms capable of increasing throughput 10- to 100-fold compared to manual patch clamp methods. Automated patch clamp electrophysiology is poised to revolutionize the field of functional genomics for inheritable cardiac ion channelopathies. In this review, we outline i) the evolution of patch clamping, ii) the development of high-throughput automated patch clamp assays to assess cardiac ion channel variants, iii) clinical application of these assays and iv) where the field is heading.

Statement from the Asia Summit: Current state of arrhythmia care in Asia

On May 27, 2022, the Asia Pacific Heart Rhythm Society and the Heart Rhythm Society convened a meeting of leaders from different professional societies of healthcare providers committed to arrhythmia care from the Asia Pacific region. The overriding goals of the meeting were to discuss clinical and health policy issues that face each country for providing care for patients with electrophysiologic issues, share experiences and best practices, and discuss potential future solutions. Participants were asked to address a series of questions in preparation for the meeting. The format of the meeting was a series of individual country reports presented by the leaders from each of the professional societies followed by open discussion. The recorded presentations from the Asia Summit can be accessed at https://www.heartrhythm365.org/URL/asiasummit-22. Three major themes arose from the discussion. First, the major clinical problems faced by different countries vary. Although atrial fibrillation is common throughout the region, the most important issues also include more general issues such as hypertension, rheumatic heart disease, tobacco abuse, and management of potentially life-threatening problems such as sudden cardiac arrest or profound bradycardia. Second, there is significant variability in the access to advanced arrhythmia care throughout the region due to differences in workforce availability, resources, drug availability, and national health policies. Third, collaboration in the area already occurs between individual countries, but no systematic regional method for working together is present.

Noncoding RNAs and Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes in Cardiac Arrhythmic Brugada Syndrome

Hundreds of thousands of people die each year as a result of sudden cardiac death, and many are due to heart rhythm disorders. One of the major causes of these arrhythmic events is Brugada syndrome, a cardiac channelopathy that results in abnormal cardiac conduction, severe life-threatening arrhythmias, and, on many occasions, death. This disorder has been associated with mutations and dysfunction of about two dozen genes; however, the majority of the patients do not have a definite cause for the diagnosis of Brugada Syndrome. The protein-coding genes represent only a very small fraction of the mammalian genome, and the majority of the noncoding regions of the genome are actively transcribed. Studies have shown that most of the loci associated with electrophysiological traits are located in noncoding regulatory regions and are expected to affect gene expression dosage and cardiac ion channel function. Noncoding RNAs serve an expanding number of regulatory and other functional roles within the cells, including but not limited to transcriptional, post-transcriptional, and epigenetic regulation. The major noncoding RNAs found in Brugada Syndrome include microRNAs; however, others such as long noncoding RNAs are also identified. They contribute to pathogenesis by interacting with ion channels and/or are detectable as clinical biomarkers. Stem cells have received significant attention in the recent past, and can be differentiated into many different cell types including those in the heart. In addition to contractile and relaxational properties, BrS-relevant electrophysiological phenotypes are also demonstrated in cardiomyocytes differentiated from stem cells induced from adult human cells. In this review, we discuss the current understanding of noncoding regions of the genome and their RNA biology in Brugada Syndrome. We also delve into the role of stem cells, especially human induced pluripotent stem cell-derived cardiac differentiated cells, in the investigation of Brugada syndrome in preclinical and clinical studies.

Ethnic and racial differences in Asian populations with ion channelopathies associated with sudden cardiac death

Cardiovascular diseases are associated with several morbidities and are the most common cause of worldwide disease-related fatalities. Studies show that treatment and outcome-related differences for cardiovascular diseases disproportionately affect minorities in the United States. The emergence of ethnic and racial differences in sudden cardiac death (SCD) and related ion channelopathies complicates cardiovascular disease prevention, diagnosis, management, prognosis, and treatment objectives for patients and physicians alike. This review compiles and synthesizes current research in cardiac ion channelopathies and genetic disorders in Asian populations, an underrepresented population in cardiovascular literature. We first present a brief introduction to SCD, noting relevant observations and statistics from around the world, including Asian populations. We then examined existing differences between Asian and White populations in research, treatment, and outcomes related to cardiac ion channelopathies and SCD, showing progression in thought and research over time for each ion channelopathy. The review also identifies research that explored phenotypic abnormalities, device usage, and risk of death in Asian patients. We touch upon the unique genetic risk factors in Asian populations that lead to cardiac ion channelopathies and SCD while comparing them to White and Western populations, particularly in the United States, where Asians comprise approximately 7% of the total population. We also propose potential solutions such as improving early genetic screening, addressing barriers affecting access to medical care and device utilization, physician training, and patient education on risks.

Prediction of the Presence of Ventricular Fibrillation From a Brugada Electrocardiogram Using Artificial Intelligence

BACKGROUND

Brugada syndrome is a potential cause of sudden cardiac death (SCD) and is characterized by a distinct ECG, but not all patients with A Brugada ECG develop SCD. In this study we sought to examine if an artificial intelligence (AI) model can predict a previous or future ventricular fibrillation (VF) episode from a Brugada ECG.

METHODS AND RESULTS

We developed an AI-enabled algorithm using a convolutional neural network. From 157 patients with suspected Brugada syndrome, 2,053 ECGs were obtained, and the dataset was divided into 5 datasets for cross-validation. In the ECG-based evaluation, the precision, recall, and F1score were 0.79±0.09, 0.73±0.09, and 0.75±0.09, respectively. The average area under the receiver-operating characteristic curve (AUROC) was 0.81±0.09. On per-patient evaluation, the AUROC was 0.80±0.07. This model predicted the presence of VF with a precision of 0.93±0.02, recall of 0.77±0.14, and F1score of 0.81±0.11. The negative predictive value was 0.94±0.11 while its positive predictive value was 0.44±0.29.

CONCLUSIONS

This proof-of-concept study showed that an AI-enabled algorithm can predict the presence of VF with a substantial performance. It implies that the AI model may detect a subtle ECG change that is undetectable by humans.

Unmasking a Silent Killer and Understanding Sudden Cardiac Death in Brugada Syndrome: A Traditional Review

Brugada syndrome (BrS) is an intricate and heterogeneous genetic disorder that engenders a formidable risk of life-threatening ventricular arrhythmias (VAs). While initially regarded as an electrophysiological aberration, emergent studies have illuminated the presence of underlying structural anomalies in select BrS cases. Although mutations in the SCN5A gene encoding the α-subunit of the cardiac sodium channel were originally identified as a primary causative factor; they account for only a fraction of the syndrome's multifaceted complexity pointing at genetic heterogeneity as a contributing factor. Remarkably, BrS has been linked to a higher incidence of fatal arrhythmic incidents and sudden cardiac death (SCD) with about 4% of SCD cases thought to be caused by BrS. Patients who spontaneously exhibit type one Brugada ECGs are more likely to experience cardiac events, emphasizing the importance of early risk stratification. To aid in risk stratification, the Shanghai score; a multifactorial risk stratification scoring system that incorporates ECG, clinical history, family history, and genetic test results; is utilized to identify those most susceptible to SCD. Beyond single ECGs, evaluation of arrhythmic findings from 24-hour Holter monitoring, ECG variables, electrophysiologic study (EPS) status in the temporal domain, and EPS data collected over time are all critical factors in risk classification. Among management options avoidance of triggers, early risk stratification, and implantation of an Implantable Cardioverter-Defibrillator (ICD) are recommended for asymptomatic patients. For symptomatic patients, pharmacotherapy and ICD implantation are available, with the latter being a highly effective choice for treating and preventing lethal arrhythmias in BrS.

SCN1B Genetic Variants: A Review of the Spectrum of Clinical Phenotypes and a Report of Early Myoclonic Encephalopathy

Background: Pathogenic variants in SCN1B, the gene encoding voltage-gated sodium channel b1/b1B subunits are associated with a spectrum of epileptic disorders. This study describes a child with early myoclonic encephalopathy and a compound heterozygous variant in the SCN1B gene (p.Arg85Cys and c.3G>C/p.Met1), along with the child’s clinical response to anti-seizure medications (ASMs) and the ketogenic diet. We reviewed the current clinical literature pertinent to SCN1B-related epilepsy. Methods: We described the evaluation and management of a patient with SCN1B-related developmental and epileptic encephalopathy (DEE). We used the Medline and Pubmed databases to review the various neurological manifestations associated with SCN1B genetic variants, and summarize the functional studies performed on SCN1B variants. Results: We identified 20 families and six individuals (including the index case described herein) reported to have SCN1B-related epilepsy. Individuals with monoallelic pathogenic variants in SCN1B often present with genetic epilepsy with febrile seizures plus (GEFS+), while those with biallelic pathogenic variants may present with developmental and epileptic encephalopathy (DEE). Individuals with DEE present with seizures of various semiologies (commonly myoclonic seizures) and status epilepticus at early infancy and are treated with various antiseizure medications. In our index case, adjunctive fenfluramine was started at 8 months of age at 0.2 mg/kg/day with gradual incremental increases to the final dose of 0.7 mg/kg/day over 5 weeks. Fenfluramine was effective in the treatment of seizures, resulting in a 50% reduction in myoclonic seizures, status epilepticus, and generalized tonic-clonic seizures, as well as a 70−90% reduction in focal seizures, with no significant adverse effects. Following the initiation of fenfluramine at eight months of age, there was also a 50% reduction in the rate of hospitalizations. Conclusions: SCN1B pathogenic variants cause epilepsy and neurodevelopmental impairment with variable expressivity and incomplete penetrance. The severity of disease is associated with the zygosity of the pathogenic variants. Biallelic variants in SCN1B can result in early myoclonic encephalopathy, and adjunctive treatment with fenfluramine may be an effective treatment for SCN1B-related DEE. Further research on the efficacy and safety of using newer ASMs, such as fenfluramine in patients under the age of 2 years is needed.