A Case Report of Brugada Syndrome Associated With Physical Trauma

Brugada syndrome is an autosomal dominant channelopathy that usually affects healthy young males without apparent structural heart disease. It is associated with a spectrum of variable and dynamic clinical manifestations, high risk of life-threatening ventricular arrhythmias, and sudden cardiac death. Our patient demonstrated transient and dynamic EKG changes of both type 1 (coved) and type 2 (saddleback) ST elevation, suggestive of the Brugada pattern that was associated with physical chest trauma and stressful situations. While common triggers like fever and certain drugs are well-recognized, this case illustrates the potential for physical stress and trauma to unmask or aggravate Brugada syndrome, albeit without definitive evidence for a causal link. Ultimately, this report underscores the importance of considering a broad differential diagnosis, including Brugada syndrome, in patients presenting with unexplained syncope or characteristic EKG changes, even when traditional triggers are absent.

Ventricular fibrillation induced by fever in structurally normal hearts

Ventricular fibrillation (VF) is a life-threatening arrhythmia that usually happens in patients with structural heart diseases. However, fever-induced ventricular fibrillation in structurally normal hearts was reported, and the four main diseases associated with these cases were Brugada syndrome, long QT syndrome, idiopathic ventricular fibrillation, and non-cardiovascular diseases. In this review, we analyzed this phenomenon and its clinical characteristics.

Brugada Phenocopy Induced by Hypovolemic Hyponatremia

Brugada syndrome (BrS) is a hereditary channelopathy caused by an autosomal dominant mutation in the cardiac sodium channel gene SCN5A alpha subunit. In individuals without structural heart disease, the risk of sudden cardiac death (SCD) increases in this channelopathy with ST-segment elevation in V1-3 precordials. Brugada phenocopy (BrP) is a condition in which transient ST-segment elevations are observed, mimicking BrS electrocardiographic changes, which can occur with electrolyte and metabolic disorder scenarios. In this study, we share a case of BrP that occurred due to hypovolemic hyponatremia and recovered spontaneously with the correction of electrolyte disturbance.

Heat Stroke-Induced Takotsubo Cardiomyopathy With a Concomitant Transient Brugada-Like Electrocardiogram

A 79-year-old man presented with impaired consciousness, fever with a body temperature of 41.1°C, and an electrocardiogram showing significant ST segment elevation in leads V1-6, coved-type ST elevation in leads V1-3, and partial right bundle branch block. Echocardiography revealed notable left ventricle dysfunction with apex-based akinesis. Coronary angiography confirmed severe obstructive lesions but left ventriculography displayed the distinct apical ballooning of takotsubo cardiomyopathy (TC). This case highlights the presence of atypical electrocardiographic patterns in TC influenced by comorbidities, supporting the diagnosis of TC despite concurrent obstructive coronary artery disease.

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

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

Hepatogastric fistula: a complication of pyogenic liver abscess in a patient with the Brugarda syndrome - A rare case report

Hepatogastric fistula following pyogenic liver abscess (PLA) is a rare and fatal complication, and only a handful of cases have been reported without co-existing comorbidities of Brugarda syndrome.

Case presentation

A 22-year-old male presented to the emergency room with a known case of Brugarda pattern ECG with chief complaints of on-and-off abdominal pain and fever for 2 weeks and shortness of breath for one day. On evaluation, echocardiography showed a clot in the inferior vena cava (IVC) and right atrium (RA), and on computed tomography scan of the abdomen revealed a liver abscess with transmural gastric perforation. During, an exploratory laparotomy where a fistula joining the left lobe of the liver and stomach was detected, and an emergency excision was done. The patient was shifted to the ICU and later developed septic shock, which was managed medically.

Clinical discussion

Usually, thrombosis of the portal vein and the hepatic vein is a very common complication of a PLA but vascular complications like IVC, RA thrombosis, and hepatogastric fistula have been reported rarely. Our case is peculiar hepatogastric fistulization along with IVC/RA clots in a patient with Brugarda pattern ECG. The typical clinical manifestation of a patient with hepatogenic fistula is absent in our patient and presented with an on-off type of fever, epigastric pain, and shortness of breath and was managed surgically.

Conclusion

Hepatogasric fistula, thrombosis of the IVC, and RA are a rare complications of PLA. The patient with Brugarda syndrome is at high risk as its clinical manifestation gets exaggerated during sepsis.

Unmasking Idiopathic Brugada ECG Pattern: Inducible Type 1 Brugada Pattern in a Young Patient and Clinical Implications

Brugada syndrome is a rare inherited channelopathy associated with an increased risk of ventricular tachycardia and ventricular fibrillation, leading to syncope and sudden cardiac death. We present a case report of a young patient with an inducible type 1 Brugada pattern on an electrocardiogram (ECG), accompanied by a comprehensive literature review. The 19-year-old patient presented with dizziness and exhibited a type 2 Brugada pattern on admission ECG, which converted to a type 1 pattern following an Ajmaline test. Based on the absence of symptoms, inducible arrhythmias, or cardiac events in the patient's history, implantable cardioverter-defibrillator insertion was deemed unnecessary. Genetic testing was recommended, and screening ECGs were advised for the patient's first-degree relatives. The discussion explores the different types of Brugada patterns, their diagnostic significance, and the controversies surrounding risk stratification and management strategies. The case underscores the importance of maintaining clinical suspicion for Brugada syndrome in young patients and tailoring treatment approaches based on individual characteristics and risk factors.

Cardiac Arrest Due to Brugada Syndrome Associated With Influenza Infection: A Case Report and Literature Review

A 38-year-old Japanese male with no significant medical history but a family history of sudden cardiac death was referred for cardiac arrest. He had a fever (40°C) one day before his visit. His wife reported that he groaned while unconscious, which prompted a referral to the authors' hospital. He was febrile and experienced ventricular fibrillation in the emergency department. After the resolution of ventricular fibrillation, electrocardiography revealed a right bundle branch block with ST-segment elevation in leads V1-3, consistent with a Brugada electrocardiographic pattern; he also tested positive for influenza A infection. Antiarrhythmic and antipyretic agents were administered, and peramivir was initiated; a fatal arrhythmia did not occur. A cardioverter-defibrillator was implanted, and the patient was discharged without complications. Brugada syndrome is a genetic disease that causes fatal cardiac arrhythmias, with fever recognized to induce the Brugada electrocardiographic pattern. The mechanism of the Brugada-type electrocardiographic pattern, right bundle branch block, and ST-segment elevation in the right precordial leads is considered to be the result of an outward shift of ionic currents during early repolarization, causing a marked abbreviation of the action potential in epicardial cells of the right ventricle. Activation and inactivation kinetics for early sodium currents are faster at higher temperatures. To date, there have only been four published reports describing Brugada-like electrocardiographic changes associated with fever related to influenza infection, and this is the first report of cardiac arrest. Since influenza infection can cause high fever and trigger the fetal arrhythmia of Brugada syndrome, it is important to shorten the duration of the fever. Anti-influenza therapy may be considered in patients who have a history of sudden cardiac arrest in the family, as influenza may influence the development of the Brugada ECG pattern in these individuals. The authors also review the literature on Brugada-like electrocardiographic changes induced by influenza infection. Physicians should be aware that Brugada's electrocardiographic pattern and cardiac arrest can be caused by febrile episodes, including those related to influenza infection.

Ventricular Fibrillation in an Afebrile COVID-19 Patient Presenting With Transient Type-I Brugada Pattern

COVID-19 has been associated with an increased risk of both atrial and ventricular arrhythmias. Brugada syndrome (BrS), an inherited sodium channelopathy presenting with a characteristic ECG morphology, confers a baseline risk of ventricular arrhythmias such as ventricular fibrillation (VF), especially during febrile illnesses. However, mimics of BrS, termed Brugada phenocopies (BrP), have been noted in association with fever, electrolyte abnormalities, and toxidromes outside of viral illness. Such presentations manifest the same ECG pattern, the type-I Brugada pattern (type-I BP). Thus, the acute stage of an illness such as COVID-19, when accompanied by a first-time presentation of type-I BP, may not result in a certain diagnosis of BrS versus BrP. Thus, expert recommendations are to anticipate arrhythmia regardless of the presumed diagnosis. Here we demonstrate the importance of these guidelines and a novel report of VF in the setting of a transient type-I BP in afebrile COVID-19. We discuss the potential factors which may have triggered VF, the presentation of isolated "coved" ST elevation in V1, and the difficulty of BrS versus BrP diagnosis in acute illness. In summary, a SARS-CoV-2 positive 65-year-old male without significant cardiac history for BrS presented with type-I BP after two days of shortness of breath. Hypoxemia, hyperkalemia, hyperglycemia, elevated inflammatory markers, and acute kidney injury were present. After treatment, his ECG normalized; however, aborted VF occurred days later while afebrile and normokalemic. Follow-up ECG again revealed a type-I BP, which also became more apparent during an episode of bradycardia, a classic finding in BrS. This case suggests that there is room for larger studies to determine the prevalence and outcomes when type-I BP presents in acute COVID-19. When possible, genetic data should be obtained to confirm BrS, a notable limitation in our case. Regardless, it corroborates guideline-directed clinical management, with heightened vigilance for arrhythmia in such patients until full recovery.

Frontier and hotspot evolution in Brugada syndrome: A bibliometric analysis from 2002 to 2022

BACKGROUND

Brugada syndrome (BrS) is a genetic disorder characterized by a typical electrocardiogram pattern and predisposition to arrhythmias and sudden cardiac death. Despite our considerably evolved understanding of BrS, no bibliometrics have been performed in this research field. We aimed to analyze and visualize the characteristics of the scientific outputs, topical evolutions, and research trends of BrS over the past 2 decades using bibliometric analysis.

METHODS

The literature associated with BrS was retrieved from the Science Citation Index Expanded of the Web of Science Core Collection database. Acquired data were then visually analyzed using CiteSpace and VOSviewer.

RESULTS

3042 qualifying records were included in the final analysis. The publication outputs increased over time. The United States was the leading country in the BrS research. The University of Amsterdam (Netherlands) was the most prolific and influential institution. Pedro Brugada, Arthur Wilde, and Charles Antzelevitch exerted notable publication impact and made the most significant contributions in the field of BrS. Heart Rhythm had the highest outputs and Circulation was the most influential journal. Bundle branch block, ST-segment elevation, mechanism, management, right precordial lead, and guideline were the keywords with the strongest citation burst.

CONCLUSION

Research on BrS is prosperous. Keywords and co-citation analysis revealed that the mechanism, diagnosis, risk stratification, and management of BrS were the research hotspots. Besides, the underlying pathophysiology, novel therapies, and personalized risk assessment might be the emerging trends of future research.

Usefulness of insertable cardiac monitors for risk stratification: current indications and clinical evidence

INTRODUCTION

The 2018 ESC Syncope guidelines expanded the indications for an insertable cardiac monitor (ICM) to patients with unexplained syncope and primary cardiomyopathy or inheritable arrhythmogenic disorders.

AREAS COVERED

This review article discusses the clinical evidence for using an ICM for risk stratification in different patient populations including Brugada syndrome, long QT syndrome, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, cardiac sarcoidosis, and congenital heart disease.

EXPERT OPINION

Clinical data on the usefulness of ICMs in different patient populations is limited but most studies demonstrate early detection of clinically relevant arrhythmias, such as nonsustained ventricular tachycardia or atrial fibrillation. It is important to emphasize that the study populations usually comprise selected populations where conventional diagnostic methods fail to clarify the mechanism of symptoms. The effect of an ICM on prognosis by earlier detection of arrhythmias is difficult to demonstrate in populations with rare disease. Risk stratification in patients with cardiomyopathy or inheritable arrhythmogenic disorders remains a niche indication for ICMs. The most important indication for an ICM remains unexplained syncope in patients at low risk of SCD. Given the device costs and uncertain clinical value of device-detected arrhythmias, it is unclear whether it is also useful in non-syncopal patients.

Association of Cardiac Electrical Disorders With KCND3 Gene Mutation

Globally, cardiac channelopathies leading to electrical disorders are responsible for a significant number of sudden cardiac deaths without structural heart disease. Many genes encoding different ion channels in the heart were identified and their impairment was found to be associated with life-threatening cardiac abnormalities. KCND3, one of the genes expressed both in the heart and brain, is reported to have an association with Brugada syndrome, early-onset atrial fibrillation, early repolarization syndrome, and sudden unexplained death syndrome. KCND3 genetic screening could be a promising tool for functional studies for an understanding of the pathogenesis and genetic determinants of the above-mentioned electrical disorders.

Reentry in cardiac ventricular epicardial tissue due to SCN5A L812Q gene mutation: a computational study

Cardiovascular diseases are the major cause of sudden death. Brugada syndrome is an inherited rare disease, that leads to death due to ventricular fibrillation (VF). Brugada Syndrome is related to mutations in the genes that encode SCN5A, a subunit of sodium ion channel (NaV). This computational study investigates the mechanism of loss of function gene mutation (SCN5A L812Q) in sodium ion channel that leads to spiral wave and further develops into VF in an epicardial tissue with homozygous condition. Study was made on wild type, L812Q heterozygous mutated and homozygous mutated ventricular tissues. Ten Tusscher human ventricular cell model (TP06) was used for the simulation study. VF is developed when a spiral wave that causes ventricular arrhythmia breaks. This leads to the formation of multiple spiral waves that are activated on different regions of the ventricles called wave break. This is observed in the epicardial tissue with homozygous condition as the effect of SCN5A L812Q gene mutation. This indicates that VF occurs in the SCN5A L812Q gene mutated homozygous ventricular epicardial tissue that may further lead to Brugada syndrome.

Molecular Pathology of Sodium Channel Beta-Subunit Variants

The voltage-gated Na⁺ channel regulates the initiation and propagation of the action potential in excitable cells. The major cardiac isoform Na_V1.5, encoded by SCN5A, comprises a monomer with four homologous repeats (I-IV) that each contain a voltage sensing domain (VSD) and pore domain. In native myocytes, Na_V1.5 forms a macromolecular complex with Na_Vβ subunits and other regulatory proteins within the myocyte membrane to maintain normal cardiac function. Disturbance of the Na_V complex may manifest as deadly cardiac arrhythmias. Although SCN5A has long been identified as a gene associated with familial atrial fibrillation (AF) and Brugada Syndrome (BrS), other genetic contributors remain poorly understood. Emerging evidence suggests that mutations in the non-covalently interacting Na_Vβ1 and Na_Vβ3 are linked to both AF and BrS. Here, we investigated the molecular pathologies of 8 variants in Na_Vβ1 and Na_Vβ3. Our results reveal that Na_Vβ1 and Na_Vβ3 variants contribute to AF and BrS disease phenotypes by modulating both Na_V1.5 expression and gating properties. Most AF-linked variants in the Na_Vβ1 subunit do not alter the gating kinetics of the sodium channel, but rather modify the channel expression. In contrast, AF-related Na_Vβ3 variants directly affect channel gating, altering voltage-dependent activation and the time course of recovery from inactivation via the modulation of VSD activation.

Brugada Electrocardiogram Pattern Induced by Recreational Delta-8-Tetrahydrocannabinol (THC): A Case Report

Brugada electrocardiogram (ECG) pattern describes a characteristic right bundle branch block (RBBB) appearance with persistent ST-segment elevation in precordial leads V1 to V3, often associated with Brugada syndrome, a genetic sodium channelopathy, in the absence of ischemic or structural heart disease. Known triggers such as fever, electrolyte abnormalities, medications, or recreational drugs may elicit such an ECG pattern without a clear clinical significance yet creating a dilemma for clinicians providing care in the urgent setting. We present a case of reversible Brugada electrocardiogram pattern (BEP) after recreational use of delta-8-tetrahydrocannabinol (THC) and explore the need for further research on the safety of such an over-the-counter supplement.

Fever and Hyponatremia Unmasking Brugada Pattern Electrocardiogram in a Patient With SARS-CoV-2 Infection

Brugada syndrome is an autosomal dominant genetic disorder that primarily affects myocardial sodium channels and has been associated with an increased risk of ventricular tachyarrhythmias and sudden cardiac death. Here, we report a case of a 58-year-old Hispanic male with a history significant for prior pulmonary tuberculosis infection who presented with pleuritic left-sided chest pain associated with body aches, productive cough, fevers, and chills and was found to be positive for SARS-CoV-2 by real-time reverse-transcription-polymerase chain reaction (rRT-PCR). Electrocardiogram (ECG, EKG) on presentation demonstrated a coved ST-segment elevation in V1-V2, suggesting Brugada pattern type 1 without evidence of ischemic changes. EKG changes normalized once fever and hyponatremia improved.

Brugada Pattern Phenocopy Induced by Diabetic Ketoacidosis

Brugada syndrome is a congenital cardiac channelopathy characterized by ST-segment elevation (≥2 mm) and subsequent inverted T wave in a minimum of two right precordial leads (Brugada type 1 ECG [electrocardiogram] pattern) on ECG. Brugada syndrome is estimated to be responsible for 4%-12% of all sudden cardiac deaths and up to 20% in patients with structurally normal hearts. Development of a temporary Brugada pattern, known as Brugada phenocopy, has been observed in individuals presenting with reversible underlying conditions such as hyperkalemia, hyponatremia, acidosis, ischemia, and pulmonary embolism, among others. Herein we present a case of Brugada phenocopy seen in a patient in diabetic ketoacidosis, which resolved after the electrolyte abnormalities were corrected.

Role of Pharmacogenetics in Adverse Drug Reactions: An Update towards Personalized Medicine

Adverse drug reactions (ADRs) are an important and frequent cause of morbidity and mortality. ADR can be related to a variety of drugs, including anticonvulsants, anaesthetics, antibiotics, antiretroviral, anticancer, and antiarrhythmics, and can involve every organ or apparatus. The causes of ADRs are still poorly understood due to their clinical heterogeneity and complexity. In this scenario, genetic predisposition toward ADRs is an emerging issue, not only in anticancer chemotherapy, but also in many other fields of medicine, including hemolytic anemia due to glucose-6-phosphate dehydrogenase (G6PD) deficiency, aplastic anemia, porphyria, malignant hyperthermia, epidermal tissue necrosis (Lyell's Syndrome and Stevens-Johnson Syndrome), epilepsy, thyroid diseases, diabetes, Long QT and Brugada Syndromes. The role of genetic mutations in the ADRs pathogenesis has been shown either for dose-dependent or for dose-independent reactions. In this review, we present an update of the genetic background of ADRs, with phenotypic manifestations involving blood, muscles, heart, thyroid, liver, and skin disorders. This review aims to illustrate the growing usefulness of genetics both to prevent ADRs and to optimize the safe therapeutic use of many common drugs. In this prospective, ADRs could become an untoward "stress test," leading to new diagnosis of genetic-determined diseases. Thus, the wider use of pharmacogenetic testing in the work-up of ADRs will lead to new clinical diagnosis of previously unsuspected diseases and to improved safety and efficacy of therapies. Improving the genotype-phenotype correlation through new lab techniques and implementation of artificial intelligence in the future may lead to personalized medicine, able to predict ADR and consequently to choose the appropriate compound and dosage for each patient.

Type 2 Brugada Electrocardiogram Pattern Due to Supra-Therapeutic Phenytoin Level

Brugada syndrome (BS) is a hereditary cardiac disease leading to sudden cardiac death. It does not display any structural cardiac abnormalities. It was first described in 1992, as the syndrome of ‘right bundle branch block, persistent ST segment elevation, and sudden death.’ Brugada phenocopy (BP) is a relatively new term used to describe electrocardiogram (ECG) patterns that resemble BS but are due to other reversible causes such as electrolyte abnormalities, fever, cocaine or alcohol intoxication, and side effect of certain medications such as sodium channel blockers, beta blockers, antidepressants, alpha adrenergic blockers, etc. Earlier studies have shown that patients taking sodium channel blocking antiepileptic drugs (AEDs) especially phenytoin can have Brugada type 1 like ECG pattern. Previously, type 2 ECG pattern secondary to supra-therapeutic phenytoin level has not been described. We describe a case with type 2 Brugada ECG pattern due to supra-therapeutic phenytoin level; the ECG pattern completely resolved following lowering the phenytoin to a therapeutic level. These patients need special considerations in ED management, disposition, and follow-up.

iPSC-Cardiomyocyte Models of Brugada Syndrome-Achievements, Challenges and Future Perspectives

Brugada syndrome (BrS) is an inherited cardiac arrhythmia that predisposes to ventricular fibrillation and sudden cardiac death. It originates from oligogenic alterations that affect cardiac ion channels or their accessory proteins. The main hurdle for the study of the functional effects of those variants is the need for a specific model that mimics the complex environment of human cardiomyocytes. Traditionally, animal models or transient heterologous expression systems are applied for electrophysiological investigations, each of these models having their limitations. The ability to create induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), providing a source of human patient-specific cells, offers new opportunities in the field of cardiac disease modelling. Contemporary iPSC-CMs constitute the best possible in vitro model to study complex cardiac arrhythmia syndromes such as BrS. To date, thirteen reports on iPSC-CM models for BrS have been published and with this review we provide an overview of the current findings, with a focus on the electrophysiological parameters. We also discuss the methods that are used for cell derivation and data acquisition. In the end, we critically evaluate the knowledge gained by the use of these iPSC-CM models and discuss challenges and future perspectives for iPSC-CMs in the study of BrS and other arrhythmias.

Peptide-Based Targeting of the L-Type Calcium Channel Corrects the Loss-of-Function Phenotype of Two Novel Mutations of the CACNA1 Gene Associated With Brugada Syndrome

Brugada syndrome (BrS) is an inherited arrhythmogenic disease that may lead to sudden cardiac death in young adults with structurally normal hearts. No pharmacological therapy is available for BrS patients. This situation highlights the urgent need to overcome current difficulties by developing novel groundbreaking curative strategies. BrS has been associated with mutations in 18 different genes of which loss-of-function (LoF) CACNA1C mutations constitute the second most common cause. Here we tested the hypothesis that BrS associated with mutations in the CACNA1C gene encoding the L-type calcium channel (LTCC) pore-forming unit (Ca_vα1.2) is functionally reverted by administration of a mimetic peptide (MP), which through binding to the LTCC chaperone beta subunit (Ca_vβ2) restores the physiological life cycle of aberrant LTCCs. Two novel Ca_vα1.2 mutations associated with BrS were identified in young individuals. Transient transfection in heterologous and cardiac cells showed LoF phenotypes with reduced Ca²⁺ current (I_Ca). In HEK293 cells overexpressing the two novel Ca_vα1.2 mutations, Western blot analysis and cell surface biotinylation assays revealed reduced Ca_vα1.2 protein levels at the plasma membrane for both mutants. Nano-BRET, Nano-Luciferase assays, and confocal microscopy analyses showed (i) reduced affinity of Ca_vα1.2 for its Ca_vβ2 chaperone, (ii) shortened Ca_vα1.2 half-life in the membrane, and (iii) impaired subcellular localization. Treatment of Ca_vα1.2 mutant-transfected cells with a cell permeant MP restored channel trafficking and physiologic channel half-life, thereby resulting in I_Ca similar to wild type. These results represent the first step towards the development of a gene-specific treatment for BrS due to defective trafficking of mutant LTCC.

Brugada Pattern Type 2 Diagnosis Unmasked by Aspiration Pneumonia

Brugada syndrome (BrS) is a rare autosomal dominant mutation affecting sodium channels. Electrocardiography can show two Brugada patterns (BrP). Type 1 BrP usually causes sudden cardiac arrest (SCA). Type 2 BrP can appear during circumstances that result in delayed sodium channel opening, such as fever, pneumonia, or use of sodium channel blockers. Patients with type 2 BrP often have underlying type 1 BrP; this can be confirmed by an ajmaline challenge test. We describe the case of a patient who presented with SCA. He later had an interval type 2 BrP secondary to aspiration pneumonia, followed by type 1 BrP pattern confirmed by an ajmaline challenge test. The patient ultimately underwent implantable cardiac defibrillator placement to prevent future SCA.

Transient Brugada Pattern Induced by Loperamide Abuse

Brugada syndrome (BrS) is classically a malignant, genetically determined, arrhythmic syndrome manifesting as syncope or sudden cardiac death (SCD) in individuals with structurally normal hearts. An exceedingly rare cause of an induced electrocardiogram (ECG) pattern mimicking BrS is secondary to loperamide abuse. The following case describes the onset of a transient Brugada pattern secondary to loperamide abuse in a young healthy male.

Tpeak-Tend, Tpeak-Tend dispersion and Tpeak-Tend/QT in children and its relationship with clinical variables

Aim

To characterize the Tpeak-Tend, the Tpeak-Tend dispersion and Tpeak-Tend/QT in children and its relationship with clinical variables.

Methods

Cross-sectional study in 126 children between 9 and 12 years of the Camilo Cienfuegos School in Santa Clara, Cuba. Clinical and anthropometric variables were obtained to determine their relationship with electrocardiographic parameters: Tpeak-Tend V5, Tpeak-Tend dispersion and Tpeak-Tend/QT ratio V5. In addition, laboratory tests were conducted.

Results

Age and systolic blood pressure are associated with an increased probability of having values of Tpeak-Tend/QT V5 ≥75 percentile for both sexes (OR: 1.72, CI 95%: 1.02-2.91; p= 0.043), (OR: 1.08, CI 95%: 1.01-1.16; p= 0.017) respectively. The body mass index and systolic blood pressure are linearly and significantly correlated with the Tpeak-Tend/QT V5 (r= 0.224; p= 0.012) and (r= 0.220; p= 0.014) respectively.

Conclusions

The age of the patients and the systolic blood pressure figures are factors that increase the probability of having values of the Tpeak-Tend/QT V5 ≥75 percentile. There was a significant linear correlation between the Tpeak-Tend/QT V5 with the body mass index and the systolic blood pressure.

Sudden cardiac death in families with premature cardiovascular disease

Objective

Sudden cardiac death (SCD) in families with premature atherosclerosis (PAS) is generally attributed to lethal arrhythmias during myocardial infarction. Yet, such arrhythmias may also arise from non-ischaemic inherited susceptibility. We aimed to test the hypothesis that Brugada syndrome is prevalent among families with PAS in which SCD occurred.

Methods

We investigated all patients who underwent Ajmaline testing to screen them for Brugada syndrome because of unexplained familial SCD in the Amsterdam University Medical Centers between 2004 and 2017. We divided the cohort into two groups based on a positive family history for PAS. All individuals with a positive Ajmaline test were screened for SCN5A-mutation.

Results

In families with SCD and PAS, the prevalence of positive Ajmaline test was similar to families with SCD alone (22% vs 19%). The number of SCD cases in families with SCD and PAS was higher (2.34 vs 1.63, p<0.001) and SCD occurred at older age in families with SCD and PAS (42 years vs 36 years, p<0.001), while the prevalence of SCN5A mutations was lower (3% vs 18%, p<0.05).

Conclusions

Brugada syndrome has a similar prevalence in families with SCD and PAS as in families with SCD alone, although SCD in families with SCD and PAS occurs in more family members and at older age, while SCN5A mutations in these families are rare. This suggests that the SCD occurring in families with PAS could be related to an underlying genetic predisposition of arrhythmias, with a different genetic origin. It could be considered to screen families with SCD and PAS for Brugada syndrome.

Long-term prognosis of patients withJ-wave syndrome

OBJECTIVE

Limited data are currently available regarding the long-term prognosis of patients with J-wave syndrome (JWS). The aim of this study was to investigate the long-term prognosis of patients with JWS and identify predictors of the recurrence of ventricular fibrillation (VF).

METHODS

This was a multicentre retrospective study (seven Japanese hospitals) involving 134 patients with JWS (Brugada syndrome (BrS): 85; early repolarisation syndrome (ERS): 49) treated with an implantable cardioverter defibrillator. All patients had a history of VF. All patients with ERS underwent drug provocation testing with standard and high intercostal ECG recordings to rule out BrS. The impact of global J waves (type 1 ECG or anterior J waves and inferolateral J waves in two or more leads) on the prognosis was evaluated.

RESULTS

During the 91±66 months of the follow-up period, 52 (39%) patients (BrS: 37; ERS: 15) experienced recurrence of VF. Patients with BrS and ERS with global J waves showed a significantly higher incidence of VF recurrence than those without (BrS: log-rank, p=0.014; ERS: log-rank, p=0.0009). The presence of global J waves was a predictor of VF recurrence in patients with JWS (HR: 2.16, 95% CI 1.21 to 3.91, p=0.0095), while previously reported high-risk electrocardiographic parameters (high-amplitude J waves ≥0.2 mV and J waves associated with a horizontal or descending ST segment) were not predictive of VF recurrence.

CONCLUSIONS

This multicentre long-term study showed that the presence of global J waves was associated with a higher incidence of VF recurrence in patients with JWS.

Meta-Analysis of Risk Stratification of SCN5A With Brugada Syndrome: Is SCN5A Always a Marker of Low Risk?

Background: SCN5A with Brugada syndrome (BrS) is not commonly considered as an independent risk marker for subsequent cardiac events. However, the risk of SCN5A combined with other clinical characteristics has not been fully investigated. Objectives: The aim of this study is to investigate and evaluate risk stratification and related risk factors of SCN5A in BrS. Methods: The databases of PubMed, EMBASE, Cochrane Library, MEDLINE, Chinese National Knowledge Infrastructure (CNKI) and Wanfang Data were searched for related studies published from January 2002 to May 2018 followed by meta-analysis. The BrS patients who underwent SCN5A gene tests were included. The prognosis and risk stratification of SCN5A combined with symptoms and asymptoms diagnosis in BrS, electrophysiology study (EPS) were then investigated and evaluated. Outcomes were defined as ventricular tachycardia/fibrillation (VT/VF), sudden cardiac death (SCD). Results: Eleven suitable studies involving 1892 BrS patients who underwent SCN5A gene tests were identified. SCN5A (+) was not considered to be a significant predictor of future cardiac events (95% CI: 0.89-2.11; P = 0.15; I 2 = 0%). However, SCN5A (+) patients with symptoms at diagnosis revealed a higher prevalence of future VT/VF, SCD compared to SCN5A (-) patients with symptoms at diagnosis. (95% CI: 1.06-3.70; P = 0.03 I 2 = 0%) Among asymptomatic patients, the risk did not significantly differ between SCN5A (+) patients and SCN5A (-) patients. (95% CI: 0.51-4.72; P = 0.45 I 2 = 0 %). In an investigation involving patients in EPS (-) BrS electrocardiogram (ECG), the risk of SCN5A (+) is higher than that of SCN5A (-) (P < 0.001). Conclusions: In BrS patients with symptoms at diagnosis or EPS (-), the meta-analysis suggests that SCN5A (+) are at a higher risk of arrhythmic events than SCN5A (-).

Cardiac conduction defects

Defects in cardiac electric impulse formation or conduction can lead to an irregular beat (arrhythmia) that can cause sudden death without any apparent cause or after stress. In the following sections, we describe the genetic disorders associated with primary cardiac conduction defects, primarily caused by mutations in ion channel genes. Primary indicates that these disorders are not caused by drugs and are not secondary to other disorders like cardiomyopathies (described in the next section).

Integration of "Omics" Strategies for Biomarkers Discovery and for the Elucidation of Molecular Mechanisms Underlying Brugada Syndrome

PURPOSE

The Brugada syndrome (BrS) is a severe inherited cardiac disorder. Given the high genetic and phenotypic heterogeneity of this disease, three different "omics" approaches are integrated in a synergic way to elucidate the molecular mechanisms underlying the pathophysiology of BrS as well as for identifying reliable diagnostic/prognostic markers.

EXPERIMENTAL DESIGN

The profiling of plasma Proteome and MiRNome is perfomed in a cohort of Brugada patients that were preliminary subjected to genomic analysis to assess a peculiar gene mutation profile.

RESULTS

The integrated analysis of "omics" data unveiled a cooperative activity of mutated genes, deregulated miRNAs and proteins in orchestrating transcriptional and post-translational events that are critical determining factors for the development of the Brugada pattern.

CONCLUSIONS AND CLINICAL RELEVANCE

This study provides the basis to shed light on the specific molecular fingerprints underlying BrS development and to gain further insights on the pathogenesis of this life-threatening cardiac disease.

A Case of Brugada Pattern Associated with Adrenal Insufficiency

Brugada syndrome (BrS) is an inherited channelopathy disease, caused by genetic changes in transmembrane ion channels. It has an increased risk of sudden cardiac death (SCD) in the absence of a structural heart disease. We report a case in which the presenting electrocardiogram (EKG) exhibited a type 1 Brugada-like pattern during an adrenal crisis with transformation into a type 2 Brugada-like pattern as the crisis improved.

A case report of Brugada-like ST-segment elevation probably due to coronary vasospasm

RATIONALE

Vasospastic angina is caused by sudden occlusive vasoconstriction of a segment of an epicardial artery, with transient ST-segment elevation on electrocardiography. Brugada Syndrome is an inherited arrhythmogenic cardiac disorder with a diagnostic electrocardiography characterized by coved-type ST-segment elevation in right precordial leads (V1-V3). Those two diseases usually have no correlation. In this report, we discuss an interesting case of a patient who was diagnosed as vasospastic angina according to his coronary angiography, but his electrocardiography showed a Brugada-like ST-segment elevation.

PATIENT CONCERNS

Our patient had a 9-month history of temporary but progressive substernal burning sensation with acid bilges of shoulders and arms, as well as profuse sweating at night.

DIAGNOSES

Although he had no abnormal laboratory test result, no dysfunctional recorded echocardiogram or documented arrhythmia after being admitted to the hospital, his electrocardiography showed a Brugada-like ST-segment elevation. The coronary angiography result confirmed a diagnosis of vasospastic angina.

INTERVENTIONS

The patient was prescribed diltiazem, aspirin, isosorbide mononitrate and rosuvastatin and was strongly advised to quit cigarettes and alcohol.

OUTCOMES

Follow-up at half a year turned out well.

LESSONS

This case links Brugada syndrome to coronary vasospasm. They may share similar mechanisms. Provocation test and gene test needs to be ran to distinguish both. Long-term follow-up is essential for it may bring a warning sign for life threatening ventricular arrhythmias.

Epicardial radiofrequency catheter ablation of Brugada syndrome with electrical storm during ventricular fibrillation: A case report

RATIONALE

Brugada syndrome (BrS) is characterized by ST segment elevation at the J point ≥2 mm in the right precordial electrocardiogram (ECG) leads, in the absence of structural heart disease, electrolyte disturbances, or ischemia. It is a well-described cause of sudden death in young patients, especially in the age of between 30 and 40 years old. Here, we reported an unusual case of electrical storm (ES) of ventricular fibrillation (VF) caused by BrS with complete right bundle-branch block (CRBBB) in a 75-year-old male patient.

PATIENT CONCERNS

A 75-year-old male patient survived sudden cardiac death caused by a ventricular ES. He presented with the cove-shaped ST elevation of 2 mm in lead V1 with typical CRBBB and lacked structural cardiomyopathy and coronary heart disease. The patient suffered ventricular ES again, although the implantable cardioverter defibrillator(ICD) had implanted.

DIAGNOSES

Brugada syndrome with complete right bundle-branch block.

INTERVENTIONS

Implantable cardioverter defibrillator (ICD) implantation was performed. But this therapy could not prevent the recurrence of malignant arrhythmia. Finally, the ES was treated successfully using radiofrequency catheter ablation (RFCA) at the area of the free wall of the right ventricular outflow tract (RVOT) epicardium.

OUTCOMES

During 7 months of follow-up, the patient was asymptomatic and free of arrhythmic events.

LESSONS

As far as we know, the patient is the oldest patient reported to have BrS. RFCA offers an alternative therapy for patients with BrS, especially when ICD shocks are encountered.

Case report: an unusual case of Brugada syndrome combined with a ventricular septal defect: A case report

RATIONALE

Brugada syndrome (BrS) is a cardiac ion channel disease that is caused by an autosomal dominant genetic abnormality. A ventricular septal defect is a common congenital heart disease, in which genetic defects play a significant role.

PATIENT CONCERNS

We report an extremely rare case of a 42-year-old male with congenital heart disease, who suffered recurrent syncope and gastrointestinal bleeding. His electrocardiogram showed an unusual right bundle branch block-like pattern and ST-segment elevation in leads V1-V3.

DIAGNOSES

The patient was eventually diagnosed with Brugada Syndrome Combined with a Ventricular Septal Defect.

INTERVENTIONS

The patient was treated with ICD implants.

OUTCOMES

We extracted his blood and performed whole exome sequencing. Whole exome sequencing revealed mutations in genes, which encode ion channels and proteins important for embryonic heart development. However, a novel mutation in the SCN5A gene was also found.

LESSONS

To our knowledge, this is the first genetically proven case of BrS combined with a ventricular septal defect.

Delayed diagnosis of Brugada syndrome in a patient with aborted sudden cardiac death and initial negative flecainide challenge

A negative flecainide challenge does not rule out Brugada syndrome even in the presence of nonfatal cardiac arrest as the first manifestation of the disease. This should prompt clinicians to ensure long‐term ECG follow‐up and consider repeating a drug test with another sodium channel blocker.

Brugada syndrome, Brugada phenocopy or none?

Brugada syndrome is a form of inherited arrhythmia syndrome characterized by a distinct ST-segment elevation in the right precordial leads. Brugada phenocopies are clinical entities that present with an electrocardiographic pattern identical to Brugada syndrome and may obey to various clinical conditions. We present a case of a suicidal attempt using a high dose of propafenone causing a Brugada-type electrocardiographic pattern. Is this a Brugada syndrome case, a Brugada phenocopy or something else?

Outcomes of Brugada Syndrome Patients with Coronary Artery Vasospasm

Objective To evaluate the outcomes of patients with concomitant Brugada syndrome and coronary artery vasospasm. Methods Patients diagnosed with Brugada syndrome with an implantable cardiac defibrillator were retrospectively investigated, and the coexistence of vasospasm was evaluated. The clinical features and outcomes were evaluated, especially in patients with coexistent vasospasm. A provocation test using acetylcholine was performed in patients confirmed to have no organic stenosis on percutaneous coronary angiography to confirm the presence of vasospasm. Implantable cardiac defibrillator shock status was checked every three months. Statistical comparisons of the groups with and without vasospasm were performed. A univariate analysis was also performed, and the odds ratio for the risk of implantable cardiac defibrillator shock was calculated. Patients Thirty-five patients with Brugada syndrome, of whom six had coexistent vasospasm. Results There were no significant differences in the laboratory data, echocardiogram findings, disease, or the history of taking any drugs between patients with and without vasospasm. There were significant differences in the clinical features of Brugada syndrome, i.e. cardiac events such as resuscitation from ventricular fibrillation or appropriate implantable cardiac defibrillator shock. Four patients with vasospasm had cardiac events such as resuscitation from ventricular fibrillation and/or appropriate defibrillator shock; three of them had no cardiac events with calcium channel blocker therapy to prevent vasospasm. The coexistence of vasospasm was a potential risk factor for an appropriate implantable cardiac defibrillator shock (odds ratio: 13.5, confidence interval: 1.572-115.940, p value: 0.035) on a univariate analysis. Conclusion Coronary artery vasospasm could be a risk factor for cardiac events in patients with Brugada syndrome.

A meta-analytic review of prevalence for Brugada ECG patterns and the risk for death

BACKGROUND

The prevalence of Brugada ECG pattern (BrEP) is different in different regions, and its mean prevalence over the world is unknown. The risk of people with BrEP for death remains unknown. We performed a meta-analysis to determine the prevalence of BrEP and risk ratio (RR) for death.

METHODS

Relevant studies published between July 1, 2000 and August 20, 2016, which contain prevalence and RR for all-cause death and cardiac death, were included. The prevalence and RR are analyzed using meta-analysis.

RESULTS

We finally retrieved 24 studies of the prevalence for BrEP and 5 studies of the RR for all-cause death and cardiac death. The worldwide mean prevalence of BrEP is 0.4%, with highest in Asia (0.9%) and lowest in North America (0.2%). Additionally, the mean prevalence in male is 0.9%, whereas it is 0.1% in female. The RR of BrEP for all-cause death is 0.78 (95% confidence interval 0.45-1.37), and for cardiac death it is 0.92 (95% confidence interval 0.23-3.66).

CONCLUSION

The prevalence of BrEP is about 0.4% around the world with different prevalence in region and sex. Our study shows that BrEP may not be taken as a predictor of all-cause death and cardiac death.

Does Sudden Unexplained Nocturnal Death Syndrome Remain the Autopsy-Negative Disorder: A Gross, Microscopic, and Molecular Autopsy Investigation in Southern China

OBJECTIVE

To look for previously unrecognized cardiac structural abnormalities and address the genetic cause for sudden unexplained nocturnal death syndrome (SUNDS).

METHODS

Data for 148 SUNDS victims and 444 controls (matched 1:3 on sex, race, and age of death within 1 year) were collected from Sun Yat-sen University from January 1, 1998, to December 31, 2014, to search morphological changes. An additional 17 patients with Brugada syndrome (BrS) collected from January 1, 2006, to December 31, 2014, served as a comparative disease cohort. Target-captured next-generation sequencing for 80 genes associated with arrhythmia/cardiomyopathy was performed in 44 SUNDS victims and 17 patients with BrS to characterize the molecular spectrum.

RESULTS

The SUNDS victims had slight but statistically significant increased heart weight and valve circumference compared with controls. Twelve of 44 SUNDS victims (SCN5A, SCN1B, CACNB2, CACNA1C, AKAP9, KCNQ1, KCNH2, KCNJ5, GATA4, NUP155, ABCC9) and 6 of 17 patients with BrS (SCN5A, CACNA1C; P>.05) carried rare variants in primary arrhythmia-susceptibility genes. Only 2 of 44 SUNDS cases compared with 5 of 17 patients with BrS hosted a rare variant in the most common BrS-causing gene, SCN5A (P=.01). Using the strict American College of Medical Genetics guideline-based definition, it was found that only 2 of 44 (KCNQ1) SUNDS and 3 of 17 (SCN5A) patients with BrS hosted a "(likely) pathogenic" variant. Fourteen of 44 SUNDS cases with cardiomyopathy-related variants had a subtle but significantly decreased circumference of cardiac valves, and tended to die on average 5 to 6 years younger compared with the remaining 30 cases (P=.02).

CONCLUSION

We present the first comprehensive autopsy evidence that SUNDS victims may have concealed cardiac morphological changes. SUNDS and BrS may result from different molecular pathological underpinnings. The distinct association between cardiomyopathy-related rare variants and SUNDS warrants further investigation.

QRS fragmentation: its role in sherlocking the arrhythmogenic heart

The electrocardiogram (ECG) is a commonly available basic diagnostic modality in in-patient, out-patient, and emergency departments. In patients with coronary artery disease (CAD), the presence of a fragmented QRS (f-QRS), which is an extra R wave (R′), notching of the single R wave, notching of the S wave in at least two contiguous leads on the 12-lead ECG, is associated with a myocardial scar from previous myocardial injury. Furthermore, the presence of f-QRS has been shown to be associated with adverse outcomes in CAD and non-CAD patients. In the present paper, we will solely focus on the usefulness and utilization of f-QRS in predicting ventricular tachyarrhythmia in many heart diseases, that is, ischemic cardiomyopathy, non-ischemic cardiomyopathy, hypertrophic obstructive cardiomyopathy, Brugada syndrome, and arrhythmogenic right ventricular cardiomyopathy. In the majority of such cases, ventricular tachyarrhythmia results in sudden cardiac death. Diagnosing them beforehand can lead to prevention and/or early treatment of these arrhythmias to prevent potential morbidity and mortality.

Risk factors for cardiac events in patients with Brugada syndrome: A PRISMA-compliant meta-analysis and systematic review

INTRODUCTION

Inconsistent results have been reported about the risk stratification of patients with Brugada syndrome. We have summarized the evidence regarding the strength of association between 6 risk factors (family history of sudden cardiac death [SCD] or syncope, inducible ventricular arrhythmias on electrophysiology study [EPS], spontaneous type 1 Brugada electrocardiogram [ECG], male sex, family history of SCD, and sodium voltage-gated channel alpha subunit 5 [SCN5A] gene mutation) and subsequent cardiac events in Brugada syndrome patients.

METHODS

Pubmed, Ovid, Embase, and the Cochrane Library were searched for studies published between January 1992 and March 2016. Only prospective studies (27 studies, 4494 patients) that reported estimates with 95% confidence intervals (CIs) of cardiac events for the 6 risk factors were included.

RESULTS

Family history of SCD or syncope (risk ratio [RR] 4.97, 95% CI 3.96-6.23, P < 0.001), inducible ventricular arrhythmia on EPS (RR 3.56, 95% CI 1.30-9.74, P = 0.01), and spontaneous type 1 Brugada ECG (RR 4.07, 95% CI 2.23-7.41, P < 0.001) were associated with an increased risk of future cardiac events. Spontaneous type 1 Brugada ECG was associated with an elevated risk of future cardiac events in patients without a family history of SCD.

CONCLUSIONS

Inducible ventricular arrhythmias on EPS, spontaneous type 1 Brugada ECG, and family history of SCD or syncope indicate a high risk of future cardiac events in patients with Brugada syndrome. Spontaneous type 1 Brugada ECG significantly increased the risk of future cardiac events in patients without family history of SCD.

The biophysical characterization of the first SCN5A mutation R1512W identified in Chinese sudden unexplained nocturnal death syndrome

Increasing evidence observed in clinical phenotypes show that abrupt breathing disorders during sleep may play an important role in the pathogenesis of sudden unexplained nocturnal death syndrome (SUNDS). The reported Brugada syndrome causing mutation R1512W in cardiac sodium channel α subunit encoded gene SCN5A, without obvious loss of function of cardiac sodium channel in previous in vitro study, was identified as the first genetic cause of Chinese SUNDS by us. The R1512W carrier was a 38-year-old male SUNDS victim who died suddenly after tachypnea in nocturnal sleep without any structural heart disease. To test our hypothesis that slight acidosis conditions may contribute to the significant loss of function of mutant cardiac sodium channels underlying SUNDS, the biophysical characterization of SCN5A mutation R1512W was performed under both extracellular and intracellular slight acidosis at pH 7.0. The cDNA of R1512W was created using site-directed mutagenesis methods in the pcDNA3 plasmid vector. The wild type (WT) or mutant cardiac sodium channel R1512W was transiently transfected into HEK293 cells. Macroscopic voltage-gated sodium current (INa) was measured 24 hours after transfection with the whole-cell patch clamp method at room temperature in the HEK293 cells. Under the baseline conditions at pH 7.4, R1512W (-175 ± 15 pA/pF) showed about 30% of reduction in peak INa compared to WT (-254 ± 23 pA/pF, P < 0.05). Under the acidosis condition at pH 7.0, R1512W (-130 ± 17 pA/pF) significantly decreased the peak INa by nearly 50% compared to WT (-243 ± 23 pA/pF, P < 0.005). Compared to baseline condition at pH 7.4, the acidosis at pH 7.0 did not affect the peak INa in WT (P > 0.05) but decreased peak INa in R1512W (P < 0.05). This initial functional study for SCN5A mutation in the Chinese SUNDS victim revealed that the acidosis aggravated the loss of function of mutant channel R1512W and suggested that nocturnal sleep disorders-associated slight acidosis may trigger the lethal arrhythmia underlying the sudden death of SUNDS cases in the setting of genetic defect.

[Functional analysis of a novel SCN5A mutation G1712C identified in Brugada syndrome]

OBJECTIVE

To elucidate the molecular and electrophysiological mechanisms of Brugada syndrome through functional analysis of a novel SCN5A gene mutation G1712C.

METHODS

A recombinant plasmid pRc<CMV-hH1 containing the mutant human cardiac sodium channel α subunit (hH1) cDNA was constructed using in vitro PCR-based site-directed mutagenesis technique. LipofectamineTM 3000 was used to transfect the plasmid DNA into HEK293 cell line to induce stable expression of Na⁺ channel β1-subunit, and the positive colonies were selected by screening with G418.The standard liposome method was used to transiently transfect HEK293 cells with either the wild-type or mutant Na⁺ channel subunits (hH1 and mhH1, respectively), and the macroscopic Na⁺ currents were recorded using whole-cell patch-clamp technique. Data acquisition and analysis, generation of voltage commands and curve fitting were accomplished with EPC-10, PatchMaster and IGOR Pro 6.0.

RESULTS

An HEK293 cell line that stably expressed Na⁺ channel β1-subunit was successfully established. After transient transfection with the WT subunit, large Na⁺ currents were recorded from the stable β1-cell line. Transient transfection with the G1712C subunit, however, did not elicit a Na⁺ current in the cells.

CONCLUSION

Compared with normal Na⁺ channel, the wild-type channel exhibits a similar sodium current. The characteristic kinetics of sodium channel of WT-hH1 was identical to that in normal cardiac muscle cell, and the missense mutation (G1712C) in the P-loop region of the domain IV may have caused the failure of sodium channel expression.

Prevalence of Atrial Fibrillation in Patients with Brugada Syndrome in Taiwan

PURPOSE

The aim of this study was to assess the prevalence of atrial fibrillation (AF) in patients with Brugada syndrome (BrS) and their clinical characteristics in Taiwan.

METHODS

The patient group consisted of 47 symptomatic BrS patients consecutively enrolled from 2000 to 2010. The definition of BrS patients with AF was a BrS patient with at least one episode of AF in a 12-lead electrogram or 24-hour holter (permanent, persistent or paroxysmal) during follow-up, or before diagnosis of BrS.

RESULTS

Six BrS patients were identified with AF, and all of them were male. Two experienced sudden cardiac death (SCD), 2 presented with seizure and 4 with syncope. The mean age at onset of BrS was 47 ± 16 years, similar to those BrS patients without AF (45 ± 14, p = 0.67). Compared to those BrS patients without AF, significantly higher percentages of the BrS patients with AF presented with seizure and documented ventricular tachyarrhythmia (p = 0.02 and 0.03, respectively). Five of them had spontaneous Brugada type I electrogram, similar to those BrS patients without AF (p = 0.9). The SCN5A mutation rate is similar between BrS patients with AF and those without AF (p = 0.69). The prevalence of AF in BrS patients in Taiwan was 12.7% (6/47, 95% confidence interval 0.06-0.19) which is not significantly lower than the 20% prevalence found in the Caucasian population (p = 0.16).

CONCLUSIONS

BrS patients with AF had distinct clinical features from those patients without AF in Taiwan.

KEY WORDS

Atrial fibrillation; Brugada syndrome; Taiwan.

Spectrum and prevalence of mutations involving BrS1- through BrS12-susceptibility genes in a cohort of unrelated patients referred for Brugada syndrome genetic testing: implications for genetic testing

OBJECTIVES

The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada syndrome (BrS)-susceptibility genes discovered to date in a single large cohort of unrelated BrS patients.

BACKGROUND

BrS is a potentially lethal heritable arrhythmia syndrome diagnosed electrocardiographically by coved-type ST-segment elevation in the right precordial leads (V1 to V3; type 1 Brugada electrocardiographic [ECG] pattern) and the presence of a personal/family history of cardiac events.

METHODS

Using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing, comprehensive mutational analysis of BrS1- through BrS12-susceptibility genes was performed in 129 unrelated patients with possible/probable BrS (46 with clinically diagnosed BrS [ECG pattern plus personal/family history of a cardiac event] and 83 with a type 1 BrS ECG pattern only).

RESULTS

Overall, 27 patients (21%) had a putative pathogenic mutation, absent in 1,400 Caucasian reference alleles, including 21 patients with an SCN5A mutation, 2 with a CACNB2B mutation, and 1 each with a KCNJ8 mutation, a KCND3 mutation, an SCN1Bb mutation, and an HCN4 mutation. The overall mutation yield was 23% in the type 1 BrS ECG pattern-only patients versus 17% in the clinically diagnosed BrS patients and was significantly greater among young men<20 years of age with clinically diagnosed BrS and among patients who had a prolonged PQ interval.

CONCLUSIONS

We identified putative pathogenic mutations in ∼20% of our BrS cohort, with BrS genes 2 through 12 accounting for <5%. Importantly, the yield was similar between patients with only a type 1 BrS ECG pattern and those with clinically established BrS. The yield approaches 40% for SCN5A-mediated BrS (BrS1) when the PQ interval exceeds 200 ms. Calcium channel-mediated BrS is extremely unlikely in the absence of a short QT interval.