Evaluation of the Necessity for Cardioverter-Defibrillator Implantation in Elderly Patients With Brugada Syndrome

Mannitol and hyponatremia regulate cardiac ventricular conduction in the context of sodium channel loss of function

Scn5a heterozygous null (Scn5a+/-) mice have historically been used to investigate arrhythmogenic mechanisms of diseases such as Brugada syndrome (BrS) and Lev's disease. Previously, we demonstrated that reducing ephaptic coupling (EpC) in ex vivo hearts exacerbates pharmacological voltage-gated sodium channel (Nav)1.5 loss of function (LOF). Whether this effect is consistent in a genetic Nav1.5 LOF model is yet to be determined. We hypothesized that loss of EpC would result in greater reduction in conduction velocity (CV) for the Scn5a+/- mouse relative to wild type (WT). In vivo ECGs and ex vivo optical maps were recorded from Langendorff-perfused Scn5a+/- and WT mouse hearts. EpC was reduced with perfusion of a hyponatremic solution, the clinically relevant osmotic agent mannitol, or a combination of the two. Neither in vivo QRS duration nor ex vivo CV during normonatremia was significantly different between the two genotypes. In agreement with our hypothesis, we found that hyponatremia severely slowed CV and disrupted conduction for 4/5 Scn5a+/- mice, but 0/6 WT mice. In addition, treatment with mannitol slowed CV to a greater extent in Scn5a+/- relative to WT hearts. Unexpectedly, treatment with mannitol during hyponatremia did not further slow CV in either genotype, but resolved the disrupted conduction observed in Scn5a+/- hearts. Similar results in guinea pig hearts suggest the effects of mannitol and hyponatremia are not species specific. In conclusion, loss of EpC through either hyponatremia or mannitol alone results in slowed or disrupted conduction in a genetic model of Nav1.5 LOF. However, the combination of these interventions attenuates conduction slowing.NEW & NOTEWORTHY Cardiac sodium channel loss of function (LOF) diseases such as Brugada syndrome (BrS) are often concealed. We optically mapped mouse hearts with reduced sodium channel expression (Scn5a+/-) to evaluate whether reduced ephaptic coupling (EpC) can unmask conduction deficits. Data suggest that conduction deficits in the Scn5a+/- mouse may be unmasked by treatment with hyponatremia and perinexal widening via mannitol. These data support further investigation of hyponatremia and mannitol as novel diagnostics for sodium channel loss of function diseases.

Opportunities and drawbacks of the subcutaneous defibrillator across different clinical settings

INTRODUCTION

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an established therapy for the prevention of sudden cardiac death (SCD) and an alternative to a transvenous implantable cardioverter-defibrillator system in selected patients. Beyond randomized clinical trials, many observational studies have described the clinical performance of S-ICD across different subgroups of patients.

AREAS COVERED

Our review aimed to describe the opportunities and drawbacks of the S-ICD, focusing on their use in special populations and across different clinical settings.

EXPERT OPINION

The choice to implant S-ICD should be based on the patient's tailored approach, which takes into account the adequate S-ICD screening at rest or during stress, the infective risk, the ventricular arrhythmia susceptibility, the progressive nature of the underlying disease, the work or sports activity, and the risk of lead-related complications.

Lights and shadows of subcutaneous implantable cardioverter-defibrillator in Brugada syndrome

Currently the cornerstone of therapy for ventricular arrhythmic complications and sudden cardiac death prevention in Brugada syndrome (BrS) is an implantable cardioverter-defibrillator (ICD). BrS patient population differs from the majority of patients with an ICD implanted for structural heart disease, and as widely known, transvenous ICD (TV-ICD) systems have been associated with high complication rates in patients with BrS. Technological evolution of these devices has certainly reduced complications due to the device itself, but a careful preimplant screening of these patients is still essential. To date, criteria for an adequate screening process to select suitable candidates for a subcutaneous implantable cardioverter-defibrillator (S-ICD) from patients with BrS are sometimes nonstandardized and often lack important precautions that are instead fundamental to select the most suitable type of ICD for these patients. To better select suitable candidates for an S-ICD from patients with BrS, a full screening process should include screening during or immediately after an exercise test and after a drug provocation challenge test. We report an analysis of the "lights and shadows" of S-ICD for a correct use of this device in patients with BrS.

Brugada syndrome: Eligibility for subcutaneous implantable cardioverter-defibrillator after exercise stress test

INTRODUCTION

Brugada syndrome (BrS) is a channelopathy associated with ventricular arrhythmias and sudden cardiac death. In patients at high risk of sudden death, an implantable cardioverter-defibrillator is indicated. Subcutaneous implantable cardioverter-defibrillators (S-ICDs) are an alternative to transvenous systems, with reduced risk of infection and complications associated with system extraction or explantation.

OBJECTIVE

To test electrocardiographic eligibility for S-ICD placement after exercise stress testing (EST) in patients with BrS.

METHODS

The sample included 35 consecutive patients with BrS. Electrocardiographic eligibility was assessed using the Boston Scientific model 2889 EMBLEM™ S-ICD automated screening tool, in four phases: decubitus and orthostatism, and before and after EST. Those who had at least one acceptable vector in the four measurements were considered eligible.

RESULTS

In this study, 71.4% of patients were male and mean age was 53.86±12 years. In screening prior to EST, 14.3% of patients (n=5) were not eligible for an S-ICD. There was a statistically significant association between ineligibility and presence of complete right bundle branch block and history of syncope. After EST, 16.7% of initially eligible patients no longer had eligible vectors (n=5).

CONCLUSION

In this study, 16.7% of patients previously eligible for an S-ICD were no longer eligible after EST. This result demonstrates the importance of screening after EST in all patients with BrS and with indication for an S-ICD, and may influence decisions concerning which ICD to implant or whether to institute pharmacological measures that avoid inappropriate therapies.

The 10-Year Prognosis and Prevalence of Brugada-Type Electrocardiograms in Elderly Women: A Longitudinal Nationwide Community-Based Prospective Study

BACKGROUND

Brugada syndrome is a disorder associated with sudden cardiac death and characterized by an abnormal electrocardiogram (ECG). Previous studies were predominantly conducted in men, and the data on long-term prognosis are limited. Information about women, especially elderly women, is lacking.

OBJECTIVE

The aim of this study was to investigate the long-term prognosis of the Brugada ECG pattern in elderly women.

METHOD

We investigated the 10-year prognosis of the Brugada ECG pattern in elderly women in a nationwide community-based population in Taiwan. Community-dwelling women older than 55 years were prospectively recruited from December 2008 to March 2013 by a stratified random sampling method. All enrolled individuals were followed up annually until April 2019, and the cause of death was documented by citizen death records.

RESULTS

Among 2597 women, 60 (2.31%) had a Brugada-type ECG, and this prevalence was higher than the mean global prevalence of 0.23%. One woman had a type 1 ECG (0.04%), whereas 15 (0.58%) and 44 (1.70%) women had type 2 and type 3 ECG patterns, respectively. Cox survival analysis revealed that all-cause mortality and cardiac mortality were similar in the individuals with and without a Brugada-type ECG during a mean follow-up of 96.1 ± 20.5 months.

CONCLUSIONS

Our findings suggest that Brugada ECG patterns are not infrequent in elderly women but are not associated with increased risk of mortality in long-term follow-up; these findings may help reduce unnecessary anxiety for physicians, nurses, allied health caregivers, and patients.

Variation of Tpeak-end, corrected Tpeak-end, QT, and corrected QT intervals, Tpeak-end/QT, Tpeak-end/corrected QT ratios and heart rate variability according to decades in the healthy male subjects aged between 30 and 79 years

Background

Heart rate variability (HRV) is a predictor of cardiac autonomic functions. Ventricular repolarization markers can indicate ventricular arrhythmias. We aimed to evaluate variations of HRV and these repolarization markers in five healthy male groups between age 30 and 79 years according to decades.

Materials and Methods

The study group consisted of 500 healthy male subjects between October 2018 and May 2019. The male subjects were divided into five categories according to their ages. Then, electrocardiograms (ECG), transthoracic echocardiograms (TTE), and treadmill exercise test (TET) were performed. T-wave peak-end (Tp-e) interval was defined as the time between the peak point and end of T-wave. Tp-e, corrected Tp-e (cTp-e), QT, and corrected QT (QTc) were measured from the resting ECGs and HRV temporal parameters (SDNN, SDNN Index, SDANN Index, RMSSD, sNN50, and pNN50), and HRV frequency parameters (VLF, LF, HF, and LF/HF) were obtained from 24-hour Holter monitorization recordings. One-way ANOVA test was used for the differences between the groups. Pearson correlation test was used to determine the correlations between the values of all groups.

Results

Considering the repolarization parameters, there are significant differences in five groups in terms of Tp-e interval, but not Tp-e/QT and Tp-e/QTc ratios. Considering the HRV parameters, there were statistically significant differences between the five male healthy groups in terms of HRV temporal parameters and there are no significant differences in terms of HRV frequency parameters.

Conclusion

As the age increases, basal Tp-e interval increases and HRV temporal parameters decrease significantly in the male subjects aged between 30 and 79 years, but HRV frequency parameters do not change.

Brugada Syndrome or Phenocopy? Diagnostic Challenge in Patients with Pectus Excavatum

Brugada syndrome is an autosomal dominant heart disease caused by dysfunctions in the ionic channels, whose carriers present a classic electrocardiographic pattern and predisposition to malignant ventricular arrhythmias. The electrocardiogram alterations may be dynamic, spontaneous, or induced by sodium channel blocking drugs (ajmaline, procainamide, etc.). However, electrocardiographic findings that diagnose Brugada syndrome may occur even in the absence of congenital dysfunction of ionic channels, characterizing “Brugada phenocopy”, therefore the exclusion of secondary causes is fundamental for the correct diagnosis of channelopathy.

Síndrome de Brugada ou Fenocópia? Desafio Diagnóstico em Paciente com Pectus Excavatum

A Síndrome de Brugada é uma doença cardíaca autossômica dominante causada por disfunções nos canais iônicos, cujos portadores apresentam padrão eletrocardiográfico clássico e predisposição a arritmias ventriculares malignas. As alterações do eletrocardiograma podem ser dinâmicas, espontâneas ou induzidas por drogas bloqueadoras dos canais de sódio (ajmalina, procainamida, etc.). No entanto, os achados eletrocardiográficos que diagnosticam Síndrome de Brugada podem ocorrer mesmo na ausência de disfunção congênita dos canais iônicos, caracterizando “fenocópia de Brugada”, portanto a exclusão de causas secundárias é fundamental para o correto diagnóstico da canalopatia.

Low-Voltage Type 1 ECG Is Associated With Fatal Ventricular Tachyarrhythmia in Brugada Syndrome

Background

Epicardial mapping can reveal low‐voltage areas on the right ventricular outflow tract in patients with Brugada syndrome with several ventricular fibrillation (VF) episodes. A type 1 ECG is associated with an abnormal electrogram on right ventricular outflow tract epicardium. This study investigated the clinical significance of the amplitude of type 1 ECGs in patients with Brugada syndrome.

Methods and Results

In 209 patients with Brugada syndrome with a spontaneous type 1 ECG (26 resuscitated from VF, 54 with syncope, and 129 asymptomatic), the amplitude of the ECG in leads exhibiting type 1 was measured among V1 to V3 leads positioned in the standard and upper 1 and 2 intercostal spaces. The number of ECG leads exhibiting type 1 did not differ among groups. The averaged amplitude of type 1 ECG was, however, significantly smaller in the group resuscitated from VF than in the asymptomatic group (P<0.05). Moreover, the minimum amplitude of type 1 ECG was significantly smaller in the group resuscitated from VF than in the group with syncope and the asymptomatic group (P<0.05 and P<0.01, respectively). During follow‐up (56±48 months), VF occurred in 29 patients. Kaplan‐Meier analysis revealed that patients with the minimum amplitude of type 1 ECG lower than or at the median value had a higher incidence of VF (log‐rank test, P<0.01). In multivariate analysis, syncope, past VF episode, and minimum amplitude of type 1 ECG ≤0.8 mV were independent predictors of VF events during follow‐up.

Conclusions

Low‐voltage type 1 ECG is highly and independently related to fatal ventricular tachyarrhythmia in patients with Brugada syndrome.

Age at diagnosis of Brugada syndrome: Influence on clinical characteristics and risk of arrhythmia

BACKGROUND

Despite a strong genetic background, Brugada syndrome (BrS) mainly affects middle-age patients. Data are scarce in the youngest and oldest age groups.

OBJECTIVE

The purpose of this study was to describe the clinical characteristics and variations in rhythmic risk in BrS patients according to age.

METHODS

Consecutive BrS patients diagnosed in 15 French tertiary centers in France were enrolled from 1993 to 2016 and followed up prospectively. All of the clinical and ECG data were double reviewed.

RESULTS

Among the 1613 patients enrolled (age 45 ± 15 years; 69% male), 3 groups were defined according to age (52 patients <17 years; 1285 between 17 and 59 years; and 276 >60 years). In the youngest patients, we identified more female gender (42%), diagnosis by familial screening (63%), previous sudden cardiac death (15%), SCN5A mutation (62%) sinus dysfunction (8%) and aVR sign (37%) (P <.001). The oldest patients had the same clinical characteristics except for gender (40% women; P <.001). During median follow-up of 5.5 [2.1, 10.0] years, 91 patients experienced an arrhythmic event, including 7 (13%) in the youngest patients, 80 (6%) in middle-age patients, and 4 (1%) in the oldest patients. Annual event rates were 2.1%, 1%, and 0.3%, respectively (P <.01).

CONCLUSION

Age on diagnosis changes the clinical presentation of BrS. Although children are identified more during familial screening, they present the highest risk of sudden cardiac death, which is an argument for early and extensive familial screening. The oldest patients present the lowest risk of SCD.

Implantable cardioverter-defibrillator in Brugada syndrome: Long-term follow-up

BACKGROUND

Brugada syndrome (BrS) is associated with sudden cardiac death (SCD). Although implantable cardioverter-defibrillator (ICD) implantation is recommended, the long-term outcomes and follow-up data with regard to ICD complications have led to controversy.

HYPOTHESIS

In the present study, we described the data assimilated in a total of 11 studies, analyzing the outcome in 747 BrS patients receiving ICD.

METHODS

Data were performed and analyzed after a systematic review of literature compiled from a thorough database search (PubMed, Web of Science, Cochrane Library, and Cinahl).

RESULTS

The mean age of patients receiving ICD was (43.1 ± 13.4, 82.5% males, 46.6% spontaneous BrS type I). Around 15.3% of the patients were admitted due to SCD and 10.4% suffered from atrial arrhythmia. Appropriate shocks were documented in 18.1% of the patients over a mean follow-up period of 82.3 months (47.5-110.4). The following complications were recorded: lead failure and fracture (5.4%), lead perforation (0.7%), lead dislodgement (1.7%), infection (3.9%), pain (0.4%), subclavian vein thrombosis (0.3%), pericardial effusion (0.1%), endocarditis (0.1%), psychiatric problems (1.5%), pneumothorax (0.7%). Inappropriate shocks were documented in 18.1% of the patients. The management of inappropriate shocks was achieved by pulmonary vein isolation (0.5%), drug treatment with sotalol (1.3%) or sotalol with beta-blocker (0.3%) and hydroquinidine (0.1%).

CONCLUSIONS

ICD therapy in BrS is associated with relevant ICD-related complications including a substantial risk of inappropriate shocks more frequently in symptomatic BrS patients.

Update on Brugada Syndrome 2019

Brugada syndrome (BrS) was first described in 1992 as an aberrant pattern of ST segment elevation in right precordial leads with a high incidence of sudden cardiac death (SCD) in patients with structurally normal heart. It represents 4% ∼ 12% of all SCD and 20% of SCD in patients with structurally normal heart. The extremely wide genetic heterogeneity of BrS and other inherited cardiac disorders makes this new area of genetic arrhytmology a fascinating one. This review shows the state of art in diagnosis, management, and treatment of BrS focusing all the aspects regarding genetics and Preimplant Genetic Diagnosis (PGD) of embryos, overlapping syndromes, risk stratification, familial screening, and future perspectives. Moreover the review analyzes key points like electrocardiogram (ECG) criteria, the role of electrophysiological study (the role of ventricular programmed stimulation and the need of universal accepted protocol) and the importance of a correct risk stratification to clarify when implantable cardioverter defibrillator or a close follow-up is needed. In recent years, cardiovascular studies have been focused on personalized risk assessment and to determine the most optimal therapy for an individual. The BrS syndrome has also benefited of these advances although there remain several key points to be elucidated. We will review the present knowledge, progress made, and future research directions on BrS.

Meta-Analysis of Clinical Outcome After Implantable Cardioverter-Defibrillator Implantation in Patients With Brugada Syndrome

OBJECTIVES

This study sought to summarize the clinical outcome of implantable cardioverter-defibrillator (ICD) therapy in patients with Brugada syndrome.

BACKGROUND

Brugada syndrome is characterized by cardiac conduction abnormalities and a high risk of ventricular arrhythmias that may result in sudden cardiac death. A complete overview of clinical outcome, appropriate and inappropriate interventions, and complications after ICD therapy in patients with Brugada syndrome is lacking.

METHODS

The online MEDLINE database was searched for published reports and yielded 828 studies on outcome and complications after ICD therapy in patients with Brugada syndrome. After careful evaluation, 22 studies including a total of 1,539 patients were included in the meta-analysis.

RESULTS

In total, 1,539 patients (mean age 45 years, 18% women) underwent ICD implantation for primary (79%) or secondary (21%) prevention of sudden cardiac death. During a mean follow-up of 4.9 years, the appropriate and inappropriate ICD intervention rates were 3.1 and 3.3 per 100 person-years, respectively. The cardiac mortality rate was 0.03 per 100 person-years and noncardiac mortality rate was 0.3 per 100 person-years. ICD-related complications per 100 person-years consisted of lead malfunction (1.6), psychological complication (1.3), infection (0.6), lead dislocation (0.4), and any complication (0.6).

CONCLUSIONS

Patients with Brugada syndrome judged to be at high risk for ventricular arrhythmia may significantly benefit from ICD therapy, which is associated with an appropriate ICD intervention rate of 3.1 per 100 person-years and low cardiac and noncardiac mortality rates. Inappropriate ICD interventions and ICD-related complications may lead to considerable morbidity.

Feasibility evaluation of long-term use of beta-blockers and calcium antagonists in patients with Brugada syndrome

Aims

Beta-blockers (BBs) and calcium antagonists (CAs) are reported to aggravate ST-segment elevation in some patients with Brugada syndrome (BrS). The feasibility of their long-term use in BrS still remains unknown. We investigated the safety of long-term use of BB and CA in BrS patients.

Methods and results

Of the 360 consecutive BrS patients, 29 [5: a history of ventricular fibrillation (VF), 17: syncope, 7: asymptomatic] took BB and/or CA (BB: 22, CA: 8) for more than 1 year for the treatment of co-morbidities such as atrial tachyarrhythmia, vasospastic angina, and neurally mediated syncope. The electrocardiographic changes and clinical outcome after the treatment were evaluated. Eleven patients showed type 1 electrocardiogram (ECG) at baseline. BBs and CAs were used within normal dosage range in all patients. After starting a BB and/or CA, type 1 ECG was still observed in 9 patients. There were no significant differences in the ECG parameters such as the amplitude of J-point, QRS duration, and corrected QT intervals before and after starting BB and/or CA. During follow-up of 89 ± 65 months after initiation of the drugs, 1 patient experienced a VF recurrence without significant changes of ECG parameters 2 years after BB therapy was started.

Conclusion

Long-term intake of BB or CA within normal dosage range was not associated with the aggravation of ECG parameters and clinical outcome in patients with BrS. The use of BBs and CAs is acceptable under careful observation.

Age of First Arrhythmic Event in Brugada Syndrome

Background

Data on the age at first arrhythmic event (AE) in Brugada syndrome are from limited patient cohorts. The aim of this study is 2-fold: (1) to define the age at first AE in a large cohort of patients with Brugada syndrome, and (2) to assess the influence of the mode of AE documentation, sex, and ethnicity on the age at first AE.

Methods and Results

A survey of 23 centers from 10 Western and 4 Asian countries gathered data from 678 patients with Brugada syndrome (91.3% men) with first AE documented at time of aborted cardiac arrest (group A, n=426) or after prophylactic implantable cardioverter–defibrillator implantation (group B, n=252). The vast majority (94.2%) of the patients were 16 to 70 years old at the time of AE, whereas pediatric (<16 years) and elderly patients (>70 years) comprised 4.3% and 1.5%, respectively. Peak AE rate occurred between 38 and 48 years (mean, 41.9±14.8; range, 0.27–84 years). Group A patients were younger than in Group B by a mean of 6.7 years (46.1±13.2 versus 39.4±15.0 years; P <0.001). In adult patients (≥16 years), women experienced AE 6.5 years later than men ( P =0.003). Whites and Asians exhibited their AE at the same median age (43 years).

Conclusions

SABRUS (Survey on Arrhythmic Events in Brugada Syndrome) presents the first analysis on the age distribution of AE in Brugada syndrome, suggesting 2 age cutoffs (16 and 70 years) that might be important for decision-making. It also allows gaining insights on the influence of mode of arrhythmia documentation, patient sex, and ethnic origin on the age at AE.

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.

Incidence of Atrial Tachyarrhythmias in Patients With Early Repolarization Syndrome

Atrial tachyarrhythmias (ATAs) occur in a significant proportion of Brugada syndrome (BrS) patients and are often an important cause of inappropriate shocks. The aim of this retrospective study was to evaluate the incidence of ATAs and ATA-induced inappropriate shocks in early repolarization syndrome (ERS) patients as compared to BrS patients.We analyzed data from 20 consecutive patients who were diagnosed with ERS and compared them with patients diagnosed with BrS (n = 31). Clinical and ICD interrogation data were collected and analyzed for all events with ICD shocks.Three patients had a history of atrial fibrillation (AF) prior to ICD implantation. One patient had AV reentrant tachycardia and was successfully ablated before ICD implantation. ATAs were newly diagnosed in 4 patients with no prior history of AF. There were no significant differences in gender, age, or left atrial diameter between ATA development. Four (20%) of 20 consecutive patients received inappropriate ICD shocks for ATAs. One suffered from repeat inappropriate shocks triggered by paroxysmal AF and received catheter ablation for AF.ATAs were not infrequent in patients with ERS and seemed to be related to inappropriate ICD therapy. Careful ICD programming is required to reduce ATA-related inappropriate ICD shock in patients with ERS.

The Brugada Syndrome - From Gene to Therapy

It is almost a quarter of century that a pioneering work of 2 researchers named Brugada brought the entire scientific community to understanding the molecular, clinical, and electrophysiological aspects of a distinctive syndrome. It affects mainly young adults with syncope and/or sudden cardiac death caused by polymorphic ventricular tachycardia or ventricular fibrillation in the absence of any sign of cardiac degeneration or alteration. Although the involvement of the epicardial layer of the right ventricular outflow tract, and the requirement of pharmacologic challenge for unveiling concealed forms, have been fully characterized, many areas of uncertainties remain to be elucidated, such as the unpredictable usefulness of programmed ventricular stimulation, the role of radiofrequency catheter ablation for reducing ST-segment elevation, and the value of risk stratification in patients diagnosed with upper displacement of right precordial leads. How much Brugada syndrome is an intense field of research is witnessed by 4 different consensus committees that took place in a relatively short period of time considering the recent discovery of this intricate arrhythmogenic disease. The main focus of this review is to describe the milestones in Brugada syndrome from its first phenotypic and genotypic appraisals to recent achievements in electrical therapies proposed for the management of this fascinating rhythm disturbance that, despite new diagnostic and therapeutic learnings, still predisposes to sudden cardiac death.

Brugada syndrome: diagnosis, risk stratification, and management

PURPOSE OF REVIEW

Asymptomatic patients with Brugada syndrome (BrS) have a small, but not trivial, risk of cardiac events. Their risk stratification and its impact on their management are controversial. The review focuses on the clinical aspects of BrS with special emphasis on the asymptomatic patient.

RECENT FINDINGS

Emerging data suggest that drug and fever-induced type I Brugada patterns are more common than previously appreciated. Although preliminary, these data may imply that asymptomatic patients with induced Brugada pattern are at an even lower risk than currently estimated.The latest data regarding induced ventricular arrhythmias during electrophysiological studies support its use as an indication for an implantable cardioverter defibrillator; however, this issue remains highly controversial.Several new risk markers, such as presence of the Brugada pattern in infero-lateral leads or the concomitant finding of an early repolarization pattern, have recently been proposed.

SUMMARY

Most asymptomatic BrS patients are at low risk of cardiac events. The presence of new risk markers in this population may prompt consideration of primary prevention measures; however, data supporting this approach are still limited.

Clinical Features of Genetic Cardiac Diseases Related to Potassium Channelopathies

Genetic cardiac diseases related to potassium channelopathies are a group of relatively rare syndromes that includes long QT syndrome, short QT syndrome, Brugada syndrome, and early repolarization syndrome. Patients with these syndromes share a propensity for the development of life-threatening ventricular arrhythmias in the absence of significant cardiac structural abnormalities. Familial atrial fibrillation has also been associated with potassium channel dysfunction but differs from the other syndromes by being a rare cause of a common condition. This article focuses on the clinical features, diagnosis, and management of these syndromes.

Brugada Syndrome: Defining the Risk in Asymptomatic Patients

Since the first description of the Brugada syndrome (BS) in 1992, scientific progress in the understanding of this disease has been enormous; at the same time more and more individuals with the disease have been diagnosed. The profile of patients with BS has changed with more asymptomatic individuals and less expressive clinical features. Asymptomatic BS individuals are at lower arrhythmic risk than those presenting with syncope or sudden cardiac death (SCD). The event incidence rate is around 0.5 % per year; this figure is relevant due to the fact that individuals have a long life expectancy and are otherwise healthy. As a result of the risk of SCD, risk stratification is of utmost importance. As the implantation of a cardioverter defibrillator is the main treatment for those patients at higher risk, benefits and long-term potential risks have to be adequately considered. Some risk factors, such as spontaneous type 1 electrocardiogram (ECG) pattern, are widely accepted, whilst for others contradictory data are present. Furthermore, novel risk factors are now available that might help in the management of BS. The presence of a spontaneous type 1 ECG pattern, history of sinus node dysfunction and inducible ventricular arrhythmias during programmed electrical stimulation of the heart allow us to risk stratify these patients.