Syncope in Brugada syndrome: prevalence, clinical significance, and clues from history taking to distinguish arrhythmic from nonarrhythmic causes

Risk stratification for the occurrence of ventricular fibrillation in patients with early repolarization syndrome

BACKGROUND

Several signs of malignant early repolarizations have been proposed in patients with early repolarization syndrome (ERS). However, reports have challenged the efficacy of these signs in predicting future ventricular fibrillation (VF) in patients with ERS.

OBJECTIVE

This study aimed to assess the predictive value of various electrocardiogram (ECG) markers for future VF events in patients with ERS.

METHODS

We retrospectively evaluated the clinical characteristics of 44 patients with ERS to identify risk factors for VF during follow-up.

RESULTS

After the initial event, 16 patients experienced VF (VF group), whereas 28 did not (non-VF group). The VF group had a longer QRS interval, more fragmented QRS (fQRS), and a higher T/R voltage ratio than the non-VF group. Wide J waves were more prevalent in the VF group; however, other J-wave markers did not differ between the groups. Positive late potentials recorded on signal-averaged ECGs were more frequent in the VF group. Whereas none of the patients showed spontaneous Brugada syndrome on ECG, the VF group frequently exhibited pilsicainide-induced ST-segment elevation. These ECG markers were significantly associated with the occurrence of VF during follow-up. Patients with multiple ECG factors, including QRS abnormalities (wide QRS or fQRS), wide J waves, and a high T/R ratio, had a worse prognosis than patients without multiple factors, effectively stratifying patient risk.

CONCLUSION

The occurrence of VF in patients with ERS may be associated with conduction abnormalities such as QRS widening, fQRS, high T/R ratio, positive late potentials, and pilsicainide test results. Therefore, ECG factors could be useful in identifying high-risk patients.

Long-term follow-up of patients with Brugada syndrome: Foremost risk factors associated with overall arrhythmic events

Brugada syndrome (BS) is characterized by ST segment elevation in right precordial leads (V1-V3), ventricular tachycardia (VT), ventricular fibrillation (VF), and sudden cardiac death (SCD) in individuals without structural heart disease. The aim of this study is to contribute to the controversial issue of finding the most valuable marker that can predict poor prognosis during follow-up in patients with a diagnosis of BS. A total of 68 patients diagnosed with BS or had Brugada-type ECG change between January 1997 and July 2012 at the Department of Cardiology of Başkent University Faculty of Medicine, Ankara, Turkey, were included in this cohort study. Patients were screened every 6 months for arrhythmia-related syncope, SCD, appropriate and inappropriate defibrillation (shock), AF development and death; collectively defined as "arrhythmic events" and were the primary endpoints. Patients with and without arrhythmic events were compared. The mean age was 34.9 ± 12.2 years (9-71 years), and 52 (76.5%) patients were male. Mean follow-up was 49.6 ± 37.6 months (4-188 months). Univariate analysis showed that male sex (P = .004), type 1 electrocardiographic pattern (P = .008), SCD (P = .036), VT/VF history (P = .046), requirement for electrophysiological studies (P = .034), implantable cardioverter-defibrillator placement (P = .014) were found to demonstrate significant differences in patients with and without arrhythmic events. In multivariable analyzes, spontaneous type 1 ECG presence (HR = 8.54, 95% CI: 0.38-26.37; P = .003) and VT/VF history (HR = 9.21, 95% CI: 0.004-1.88; P = .002) were found to be independently associated with arrhythmic events. We found the presence of spontaneous type 1 ECG and a history of VT/VF to be associated with increased likelihood of overall arrhythmic events in BS. Given the higher risk of poor prognosis, we recommend additional measures in patients with BS who have these features.

Long-term clinical outcomes of patients with drug-induced type 1 Brugada electrocardiographic pattern: A nationwide cohort registry study

BACKGROUND

There are limited real-world data on the extended prognosis of patients with drug-induced type 1 Brugada electrocardiogram (ECG).

OBJECTIVE

We assessed the clinical outcomes and predictors of life-threatening arrhythmias in patients with drug-induced type 1 Brugada ECG.

METHODS

This multicenter retrospective study, conducted at 21 Italian and Swiss hospitals from July 1997 to May 2021, included consecutive patients with drug-induced type 1 ECG. The primary outcome, a composite of appropriate ICD therapies and sudden cardiac death, was assessed along with the clinical predictors of these events.

RESULTS

A total of 606 patients (mean age 49.7 ± 14.7 years; 423 [69.8%] men) were followed for a median of 60.3 months (interquartile range 23.0-122.4 months). Nineteen patients (3.1%) experienced life-threatening arrhythmias, with a median annual event rate of 0.5% over 5 years and 0.25% over 10 years. The SCN5A mutation was the only predictor of the primary outcome (hazard ratio 4.54; P = .002), whereas a trend was observed for unexplained syncope (hazard ratio 3.85; P = .05). In patients who were asymptomatic at presentation, the median annual rate of life-threatening arrhythmias is 0.24% over 5 years and increases to 1.2% if they have inducible ventricular fibrillation during programmed ventricular stimulation.

CONCLUSION

In patients with drug-induced type 1 Brugada ECG, the annual risk of life-threatening arrhythmias is low, with the SCN5A mutation as the only independent predictor. Unexplained syncope correlated with worse clinical outcomes. Ventricular fibrillation inducibility at programmed ventricular stimulation significantly increases the median annual rate of life-threatening arrhythmias from 0.24% to 1.2% over 5 years.

Arrhythmia detection using an implantable loop recorder after a negative electrophysiology study in Brugada syndrome: Observations from a multicenter international registry

BACKGROUND

Risk stratification in Brugada syndrome (BrS) remains controversial. In this respect, the role of the electrophysiology study (EPS) has been a subject of debate. In some centers, it is common practice to use an implantable loop recorder (ILR) after a negative EPS to help in risk stratification. However, the diagnostic value of this approach has never been specifically addressed.

OBJECTIVE

The aim of this study was to describe the baseline characteristics and the main findings of a diagnostic workup strategy with an ILR after a negative EPS in BrS.

METHODS

We conducted a retrospective international registry including patients with BrS and negative EPS (ie, noninducible ventricular tachycardia or ventricular fibrillation) before ILR monitoring.

RESULTS

The study included 65 patients from 8 referral hospitals in The Netherlands, Spain, and the United Kingdom (mean age, 39 ± 16 years; 72% male). The main indication for ILR monitoring was unexplained syncope/presyncope (66.2%). During a median follow-up of 39.0 months (Q1 25.0-Q3 47.6 months), 18 patients (27.7%) experienced 21 arrhythmic events (AEs). None of the patients died during follow-up. Bradyarrhythmias were the most common finding (47.6%), followed by atrial tachyarrhythmias (38.1%). Only 3 patients presented with ventricular arrhythmias. AEs were considered incidental in 12 patients (66.7%). In 11 patients (61.1%), AEs led to specific changes in treatment.

CONCLUSION

The use of ILR after a negative EPS in BrS is a safe strategy that reflected the high negative predictive value of EPS for ventricular arrhythmia in this syndrome. In addition, it allowed the detection of AEs in a significant proportion of patients, with therapeutic implications in most of them.

Clinical Management of Brugada Syndrome: Commentary From the Experts

Although there is consensus on the management of patients with Brugada Syndrome with high risk for sudden cardiac arrest, asymptomatic or intermediate-risk patients present clinical management challenges. This document explores the management opinions of experts throughout the world for patients with Brugada Syndrome who do not fit guideline recommendations. Four real-world clinical scenarios were presented with commentary from small expert groups for each case. All authors voted on case-specific questions to evaluate the level of consensus among the entire group in nuanced diagnostic and management decisions relevant to each case. Points of agreement, points of controversy, and gaps in knowledge are highlighted.

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.

Type of syncope and outcome in Brugada syndrome: A systematic review and meta‐analysis

Introduction

Brugada syndrome is an inherited arrhythmic disease associated with major arrhythmic events (MAE). The importance of primary prevention of sudden cardiac death (SCD) in Brugada syndrome is well recognized; however, ventricular arrhythmia risk stratification remains challenging and controversial. We aimed to assess the association of type of syncope with MAE via systematic review and meta-analysis.

Methods

We comprehensively searched the databases of MEDLINE and EMBASE from inception to December 2021. Included studies were cohort (prospective or retrospective) studies that reported the types of syncope (cardiac, unexplained, vasovagal, and undifferentiated) and MAE. Data from each study were combined using the random-effects, generic inverse variance method of DerSimonian and Laird to calculate the odds ratio (OR) and 95% confidence intervals (CIs).

Results

Seventeen studies from 2005 to 2019 were included in this meta-analysis involving 4355 Brugada syndrome patients. Overall, syncope was significantly associated with an increased risk of MAE in Brugada syndrome (OR = 3.90, 95% CI: 2.22-6.85, p < .001, I ² = 76.0%). By syncope type, cardiac (OR = 4.48, 95% CI: 2.87-7.01, p < .001, I ² = 0.0%) and unexplained (OR = 4.71, 95% CI: 1.34-16.57, p = .016, I ² = 37.3%) syncope was significantly associated with increased risk of MAE in Brugada syndrome. Vasovagal (OR = 2.90, 95% CI: 0.09-98.45, p = .554, I ² = 70.9%) and undifferentiated syncope (OR = 2.01, 95% CI: 1.00-4.03, p = .050, I ² = 64.6%, respectively) were not.

Conclusion

Our study demonstrated that cardiac and unexplained syncope was associated with MAE risk in Brugada syndrome populations but not in vasovagal syncope and undifferentiated syncope. Unexplained syncope is associated with a similar increased risk of MAE compared to cardiac syncope.

Red Flags in Syncope: Clues for the Diagnosis of Idiopathic Ventricular Fibrillation

Idiopathic ventricular fibrillation is responsible for ≈5%-7% of aborted cardiac arrest, mainly striking subjects in their forties. Syncope caused by short-coupled rapid polymorphic ventricular tachycardia is frequently noted in a patient's past history. However, a diagnosis of neurally mediated syncope, the most frequent cause of syncope in the young, is often erroneously made. Clinical clues suggest that syncope has an arrhythmic rather than a neurally mediated origin. In addition, the presence of premature ventricular contractions on an electrocardiogram recorded shortly after a syncopal event has utmost importance in establishing the cause of syncope. Although such extrasystoles are frequently benign, especially when associated with a long coupling interval, they also may suggest a malignant origin when closely coupled to the preceding complex with short coupling intervals (usually <350 ms). These arrhythmias mainly originate from the Purkinje system (usually the right ventricle in men and the left ventricle in women) and favorably respond to quinidine as well as to ablation therapy targeting Purkinje-fibers ectopic activity.

Risk stratification of sudden cardiac death in Brugada syndrome: an updated review of literature

Brugada syndrome is a rare but serious inherited heart disease that causes sudden cardiac death by polymorphic ventricular tachycardia or ventricular fibrillation. It is an autosomal dominant genetic disease that usually occurs in patients in their forties with a structurally normal heart. Electrically, it manifests by ST elevation segment ≥ 2 mm of at least one right precordial lead (V1 and/or V2). Stratification of sudden cardiac death in Brugada syndrome is not always easy and constitutes a real challenge for the practitioner. In this review, we will present the current state of knowledge for arrhythmic risk stratification and the prevention of sudden cardiac death that can result from this syndrome.

Brugada Syndrome

Brugada syndrome (BrS) is an "inherited" condition characterized by predisposition to syncope and cardiac arrest, predominantly during sleep. The prevalence is ∼1:2,000, and is more commonly diagnosed in young to middle-aged males, although patient sex does not appear to impact prognosis. Despite the perception of BrS being an inherited arrhythmia syndrome, most cases are not associated with a single causative gene variant. Electrocardiogram (ECG) findings support variable extent of depolarization and repolarization changes, with coved ST-segment elevation ≥2 mm and a negative T-wave in the right precordial leads. These ECG changes are often intermittent, and may be provoked by fever or sodium channel blocker challenge. Growing evidence from cardiac imaging, epicardial ablation, and pathology studies suggests the presence of an epicardial arrhythmic substrate within the right ventricular outflow tract. Risk stratification aims to identify those who are at increased risk of sudden cardiac death, with well-established factors being the presence of spontaneous ECG changes and a history of cardiac arrest or cardiogenic syncope. Current management involves conservative measures in asymptomatic patients, including fever management and drug avoidance. Symptomatic patients typically undergo implantable cardioverter defibrillator insertion, with quinidine and epicardial ablation used for patients with recurrent arrhythmia. This review summarizes our current understanding of BrS and provides clinicians with a practical approach to diagnosis and management.

Ventricular arrhythmia management in patients with genetic cardiomyopathies

Genetic cardiomyopathies are associated with increased risk for cardiac arrhythmias and sudden cardiac death. The management of ventricular arrhythmias (VAs) in patients with these conditions can be nuanced due to particular disease-based considerations, yet data specifically addressing management in these patients are limited. Here we describe the current evidence-based approach to the management of ventricular rhythm disorders in patients with genetic forms of cardiomyopathy, namely, hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, left ventricular noncompaction, and Brugada syndrome, including recommendations from consensus guideline statements when available.

The evidence for the implantable loop recorder in patients with inherited arrhythmia syndromes: a review of the literature

Risk stratification of patients with inherited arrhythmia syndromes (IASs) can be challenging. Recent guidelines acknowledge a place for considering the implantable loop recorder (ILR) to outrule malignant arrhythmia as a cause of syncope in certain inherited arrhythmia patients who are at low risk of sudden cardiac death. In this comprehensive literature review, we evaluate the available evidence for the use of the ILR in the IASs and in relatives of victims of sudden arrhythmic death syndrome.

Brugada syndrome: update and future perspectives

Brugada syndrome (BrS) is an inherited cardiac disorder, characterised by a typical ECG pattern and an increased risk of arrhythmias and sudden cardiac death (SCD). BrS is a challenging entity, in regard to diagnosis as well as arrhythmia risk prediction and management. Nowadays, asymptomatic patients represent the majority of newly diagnosed patients with BrS, and its incidence is expected to rise due to (genetic) family screening. Progress in our understanding of the genetic and molecular pathophysiology is limited by the absence of a true gold standard, with consensus on its clinical definition changing over time. Nevertheless, novel insights continue to arise from detailed and in-depth studies, including the complex genetic and molecular basis. This includes the increasingly recognised relevance of an underlying structural substrate. Risk stratification in patients with BrS remains challenging, particularly in those who are asymptomatic, but recent studies have demonstrated the potential usefulness of risk scores to identify patients at high risk of arrhythmia and SCD. Development and validation of a model that incorporates clinical and genetic factors, comorbidities, age and gender, and environmental aspects may facilitate improved prediction of disease expressivity and arrhythmia/SCD risk, and potentially guide patient management and therapy. This review provides an update of the diagnosis, pathophysiology and management of BrS, and discusses its future perspectives.

Role of subcutaneous implantable loop recorder for the diagnosis of arrhythmias in Brugada syndrome: A United Kingdom single-center experience

BACKGROUND

Experience with implantable loop recorders (ILRs) in Brugada syndrome (BrS) is limited.

OBJECTIVE

The purpose of this study was to evaluate the indications and yield of ILR monitoring in a single-center BrS registry.

METHODS

Demographic, clinical and follow-up data of BrS patients with ILR were collected.

RESULTS

Of 415 BrS patients recruited consecutively, 50 (12%) received an ILR (58% male). Mean age at ILR implantation was 44 ± 15 years. Thirty-one (62%) had experienced syncopal or presyncopal episodes, and 23 (46%) had palpitations. During median follow-up of 28 months (range 1-68), actionable events were detected in 11 subjects (22%); 7 had recurrences of syncope/presyncope, with 4 showing defects in sinus node function or atrioventricular conduction. New supraventricular tachyarrhythmias were recorded in 6 subjects; a run of fast nonsustained ventricular tachycardia was detected in 1 patient. Patients implanted with an ILR were less likely to show a spontaneous type 1 pattern or depolarization electrocardiographic (ECG) abnormalities compared to those receiving a primary prevention implantable-cardioverter defibrillator. Age at implantation, gender, Shanghai score, and ECG parameters did not differ between subjects with and those without actionable events. ILR-related complications occurred in 3 cases (6%).

CONCLUSION

In a large cohort of BrS patients, continuous ILR monitoring yielded a diagnosis of tachy- or bradyarrhythmic episodes in 22% of cases. Recurrences of syncope were associated with bradyarrhythmic events. Use of ILR can be helpful in guiding the management of low-/intermediate-risk BrS patients and ascertaining the cause of unexplained syncope.

Brugada syndrome and syncope: a practical approach for diagnosis and treatment

Syncope in patients with Brugada electrocardiogram pattern may represent a conundrum in the decision algorithm because incidental benign forms, especially neurally mediated syncope, are very frequent in this syndrome similarly to the general population. Arrhythmic syncope in Brugada syndrome typically results from a self-terminating sustained ventricular tachycardia or paroxysmal ventricular fibrillation, potentially leading to sudden cardiac death. Distinguishing syncope due to malignant arrhythmias from a benign form is often difficult unless an electrocardiogram is recorded during the episode. We performed a review of the existing literature and propose a practical approach for diagnosis and treatment of the patients with Brugada syndrome and syncope.

Implantable loop recorders in patients with heart disease: comparison between patients with and without syncope

OBJECTIVE

Patients with heart disease are at increased risk for sudden cardiac death. Guidelines recommend an implantable loop recorder (ILR) for symptomatic patients when symptoms are sporadic and possibly arrhythmia-related. In clinical practice, an ILR is mainly used in patients with unexplained syncope. We aimed to compare the clinical value of an ILR in patients with heart disease and a history of syncope versus those with non-syncopal symptoms.

METHODS

In this observational single-centre study, we included symptomatic patients with heart disease who received an ILR. The primary endpoint was an actionable event which was defined as an arrhythmic event leading to a change in clinical management. The secondary endpoint was an event leading to device implantation.

RESULTS

One hundred and twenty patients (mean age 47±17 years, 49% men) were included. The underlying disease substrate was inherited cardiomyopathy (31%), congenital heart disease (28%), channelopathy (23%) and other (18%). Group A consisted of 43 patients with prior syncope and group B consisted of 77 patients with palpitations and/or near-syncope. The median follow-up duration was 19 months (IQR 8-36). The 3-year cumulative event rate was similar between groups with regard to the primary endpoint (38% vs 39% for group A and B, respectively, logrank p=0.54). There was also no difference in the 3-year cumulative rate of device implantation (21% vs 13% for group A and B, respectively, logrank p=0.65).

CONCLUSION

In symptomatic patients with heart disease, there is no difference in the yield of an ILR in patients presenting with or without syncope.

Syncope and electrocardiogram

INTRODUCTION

Suspected transient loss of consciousness (T-LOC) and syncope are common causes of hospitalization in older patients. Arrhythmias are the most common cardiac causes of syncope. Although a number of instrumental diagnostic procedures are usually routinely performed in patients with suspected syncope, a 12 leads electrocardiogram (ECG) is the only instrumental test recommended for the initial evaluation of these patients.

EVIDENCE ACQUISITION

In this paper current literature on this topic will be reviewed, including ECG diagnostic criteria and findings suggestive of cardiac syncope.

EVIDENCE SYNTHESIS

The ECG may disclose an arrhythmia associated with a high likelihood of syncope, avoiding further evaluations and permitting institution of specific treatment in 7% of patients referred to emergency department. When the cause of syncope remains uncertain after initial evaluation the next step is to assess the risk of major cardiovascular events or sudden cardiac death. An abnormal ECG selected patients with high probabiliry of cardiac syncope. ECG diagnostic criteria and ECG findings suggesting arrhythmic syncope are presented. Indications and potential clinical implications of ECG monitoring will be discussed too.

CONCLUSIONS

A careful, well-conducted medical history focused on the suspected syncopal event is crucial for the diagnosis. In this setting, the ECG is a mandatory diagnostic tool which, although normal in the majority of patients of syncope, has the potential to identify patients with high likelihood of cardiac syncope due to arrhythmic or cardiopulmonary disorder.

Electrophysiological Study Prognostic Value and Long-Term Outcome in Drug-Induced Type 1 Brugada Syndrome: The IBRYD Study

OBJECTIVES

This study aimed to retrospectively assess long-term outcome and the prognostic role of electrophysiological study (EPS) for risk stratification of drug-induced type 1 Brugada syndrome (BrS) patients.

BACKGROUND

BrS is a hereditary cardiac disease, predisposing to sudden cardiac death. Few real-world data are available on long-term outcomes of drug-induced type 1 BrS patients, and questions about risk stratification still remain unanswered.

METHODS

The IBRYD (Italian Brugada Syndrome) study is a multicenter observational retrospective study. A total of 226 drug-induced type 1 BrS patients were enrolled from 9 Italian tertiary referral institutions. Primary endpoint was a composite of appropriate implantable cardioverter-defibrillator (ICD) therapy and sudden cardiac death. The authors further assessed clinical predictors to ICD implantation, as well as for arrhythmia induction at EPS, along with EPS as potential risk factor for the outcomes of interest.

RESULTS

142 patients (62.8%) received an ICD due to syncope and/or inducible ventricular tachyarrhythmias at EPS. During a median follow-up of 106 months, 11 patients (4.9%) experienced primary outcome events. The ICD therapy median annual incidence over 8 years was 0.38% (interquartile range: 0% to 1.47%). Ventricular tachyarrhythmia inducibility during EPS was not predictive of arrhythmic events in ICD recipients versus non-ICD patients and in symptomatic versus asymptomatic subgroups, showing a low positive predictive value (9.6% and 8.9%, respectively) versus a high negative predictive value (96.6% and 95%, respectively). The authors reported 29 ICD-related complications and 4.9% inappropriate shocks.

CONCLUSIONS

Drug-induced type 1 BrS patients have a very low arrhythmic risk. Clinical decision for implantation is supported by syncope and/or EPS positivity, though they fail to stratify high-risk patients. A better risk-to-benefit ratio should be pursued, considering both arrhythmic risk and ICD-related complications.

High-risk atrioventricular block in Brugada syndrome patients with a history of syncope

BACKGROUND

Determining the etiology of syncope is challenging in Brugada syndrome (BrS) patients. Implantable cardioverter defibrillator placement is recommended in BrS patients who are presumed to have arrhythmic syncope. However, arrhythmic syncope in BrS patients can occur in the setting of atrioventricular block (AVB), which should be managed by cardiac pacing. The clinical characteristics of BrS patients with high-risk AVB remain unknown.

METHODS

This study included 223 BrS patients with a history of syncope from two centers. The clinical characteristics of patients with high-risk AVB (Mobitz type II second-degree AVB, high-degree AVB, or third-degree AVB) were investigated.

RESULTS

During the 99 ± 78 months of follow-up, we identified six BrS patients (2.7%) with high-risk AVB. Three of the six patients (50%) with AVB presented with syncope associated with prodromes or specific triggers. Four patients (67%) were found to have paroxysmal third-degree AVB during the initial evaluation for BrS and syncope, while two patients developed third-degree AVB during the follow-up period. The incidence of first-degree AVB was significantly higher in AVB patients than in non-AVB patients (83% vs. 15%; p = .0005). There was no significant difference in the incidence of ventricular fibrillation between AVB and non-AVB patients (AVB [17%], non-AVB [12%]; p = .56).

CONCLUSION

High-risk AVB can occur in BrS patients with various clinical presentations. Although rare, the incidence is worth considering, especially in BrS patients with first-degree AVB.

Prediction of ventricular arrhythmias in patients with a spontaneous Brugada type 1 pattern: the key is in the electrocardiogram

AIMS

There is currently no reliable tool to quantify the risks of ventricular fibrillation or sudden cardiac arrest (VF/SCA) in patients with spontaneous Brugada type 1 pattern (BrT1). Previous studies showed that electrocardiographic (ECG) markers of depolarization or repolarization disorders might indicate elevated risk. We aimed to design a VF/SCA risk prediction model based on ECG analyses for adult patients with spontaneous BrT1.

METHODS AND RESULTS

This retrospective multicentre international study analysed ECG data from 115 patients (mean age 45.1 ± 12.8 years, 105 males) with spontaneous BrT1. Of these, 45 patients had experienced VF/SCA and 70 patients did not experience VF/SCA. Among 10 ECG markers, a univariate analysis showed significant associations between VF/SCA and maximum corrected Tpeak-Tend intervals ≥100 ms in precordial leads (LMaxTpec) (P < 0.001), BrT1 in a peripheral lead (pT1) (P = 0.004), early repolarization in inferolateral leads (ER) (P < 0.001), and QRS duration ≥120 ms in lead V2 (P = 0.002). The Cox multivariate analysis revealed four predictors of VF/SCA: the LMaxTpec [hazard ratio (HR) 8.3, 95% confidence interval (CI) 2.4-28.5; P < 0.001], LMaxTpec + ER (HR 14.9, 95% CI 4.2-53.1; P < 0.001), LMaxTpec + pT1 (HR 17.2, 95% CI 4.1-72; P < 0.001), and LMaxTpec + pT1 + ER (HR 23.5, 95% CI 6-93; P < 0.001). Our multidimensional penalized spline model predicted the 1-year risk of VF/SCA, based on age and these markers.

CONCLUSION

LMaxTpec and its association with pT1 and/or ER indicated elevated VF/SCA risk in adult patients with spontaneous BrT1. We successfully developed a simple risk prediction model based on age and these ECG markers.

Incorporating Latent Variables Using Nonnegative Matrix Factorization Improves Risk Stratification in Brugada Syndrome

Background

A combination of clinical and electrocardiographic risk factors is used for risk stratification in Brugada syndrome. In this study, we tested the hypothesis that the incorporation of latent variables between variables using nonnegative matrix factorization can improve risk stratification compared with logistic regression.

Methods and Results

This was a retrospective cohort study of patients presented with Brugada electrocardiographic patterns between 2000 and 2016 from Hong Kong, China. The primary outcome was spontaneous ventricular tachycardia/ventricular fibrillation. The external validation cohort included patients from 3 countries. A total of 149 patients with Brugada syndrome (84% males, median age of presentation 50 [38–61] years) were included. Compared with the nonarrhythmic group (n=117, 79%), the spontaneous ventricular tachycardia/ ventricular fibrillation group (n=32, 21%) were more likely to suffer from syncope (69% versus 37%, P=0.001) and atrial fibrillation (16% versus 4%, P=0.023) as well as displayed longer QTc intervals (424 [399–449] versus 408 [386–425]; P=0.020). No difference in QRS interval was observed (108 [98–114] versus 102 [95–110], P=0.104). Logistic regression found that syncope (odds ratio, 3.79; 95% CI, 1.64–8.74; P=0.002), atrial fibrillation (odds ratio, 4.15; 95% CI, 1.12–15.36; P=0.033), QRS duration (odds ratio, 1.03; 95% CI, 1.002–1.06; P=0.037) and QTc interval (odds ratio, 1.02; 95% CI, 1.01–1.03; P=0.009) were significant predictors of spontaneous ventricular tachycardia/ventricular fibrillation. Increasing the number of latent variables of these electrocardiographic indices incorporated from n=0 (logistic regression) to n=6 by nonnegative matrix factorization improved the area under the curve of the receiving operating characteristics curve from 0.71 to 0.80. The model improves area under the curve of external validation cohort (n=227) from 0.64 to 0.71.

Conclusions

Nonnegative matrix factorization improves the predictive performance of arrhythmic outcomes by extracting latent features between different variables.

A Primary Prevention Clinical Risk Score Model for Patients With Brugada Syndrome (BRUGADA-RISK)

OBJECTIVES

The goal of this study was to develop a risk score model for patients with Brugada syndrome (BrS).

BACKGROUND

Risk stratification in BrS is a significant challenge due to the low event rates and conflicting evidence.

METHODS

A multicenter international cohort of patients with BrS and no previous cardiac arrest was used to evaluate the role of 16 proposed clinical or electrocardiogram (ECG) markers in predicting ventricular arrhythmias (VAs)/sudden cardiac death (SCD) during follow-up. Predictive markers were incorporated into a risk score model, and this model was validated by using out-of-sample cross-validation.

RESULTS

A total of 1,110 patients with BrS from 16 centers in 8 countries were included (mean age 51.8 ± 13.6 years; 71.8% male). Median follow-up was 5.33 years; 114 patients had VA/SCD (10.3%) with an annual event rate of 1.5%. Of the 16 proposed risk factors, probable arrhythmia-related syncope (hazard ratio [HR]: 3.71; p < 0.001), spontaneous type 1 ECG (HR: 3.80; p < 0.001), early repolarization (HR: 3.42; p < 0.001), and a type 1 Brugada ECG pattern in peripheral leads (HR: 2.33; p < 0.001) were associated with a higher risk of VA/SCD. A risk score model incorporating these factors revealed a sensitivity of 71.2% (95% confidence interval: 61.5% to 84.6%) and a specificity of 80.2% (95% confidence interval: 75.7% to 82.3%) in predicting VA/SCD at 5 years. Calibration plots showed a mean prediction error of 1.2%. The model was effectively validated by using out-of-sample cross-validation according to country.

CONCLUSIONS

This multicenter study identified 4 risk factors for VA/SCD in a primary prevention BrS population. A risk score model was generated to quantify risk of VA/SCD in BrS and inform implantable cardioverter-defibrillator prescription.

Brugada syndrome and syncope: A systematic review

INTRODUCTION

Distinguishing syncope due to malignant arrhythmias from an incidental benign form in Brugada syndrome (BrS) is often difficult. Through systematic literature review, we evaluated the role of syncope in predicting subsequent malignant arrhythmias in BrS.

METHODS

A comprehensive literature search was performed on PubMed (MeSH search terms "Brugada syndrome" and "syncope"). Overall, 9 studies for a total of 1347 patients were included. Patients were stratified as affected by suspected arrhythmic syncope (SAS), undefined syncope (US) or neurally-mediated syncope (NMS).

RESULTS

Overall, 15.7% of the 279 patients with SAS had malignant arrhythmic events during a mean follow-up of 67 months, corresponding to 2.8 events per 100/person year. At the same time, 7% of the 527 patients affected by US had malignant arrhythmias during a mean follow-up of 39 months, corresponding 2.2 events per 100/person year. Conversely, 0.7% of 541 patients with NMS had malignant arrhythmic events at follow-up, corresponding to 0.13 events per 100/person year (p = .0001 NMS versus SAS and US pooled).

CONCLUSION

In BrS population, the risk of arrhythmic events in the follow-up may be stratified according to the clinical evaluation. The "relatively" low predictive value of the clinical diagnosis of SAS warrants for a more accurate multi-parametric assessment, to restrict the number of candidates for implantable cardioverter-defibrillator therapy.

Improved Risk Stratification of Patients With Brugada Syndrome by the New Japanese Circulation Society Guideline - A Multicenter Validation Study

BACKGROUND

The new guideline (NG) published by the Japanese Circulation Society (JCS) places emphasis on previous arrhythmic syncope and inducibility of ventricular fibrillation (VF) by ≤2 extrastimuli during programmed electrical stimulation (PES) for deciding the indication of an implantable cardioverter-defibrillator in patients with Brugada syndrome (BrS). This study evaluated the usefulness of the NG and compared it with the former guideline (FG) for risk stratification of patients with BrS.Methods and Results:This was a multicenter (7 Japanese hospitals) retrospective study involving 234 patients with BrS who underwent PES at baseline (226 males; mean age at diagnosis: 44.9±13.4 years). At diagnosis, 46 patients (20%) had previous VF, 100 patients (43%) had previous syncope, and 88 patients (37%) were asymptomatic. We evaluated the difference in the incidence of VF in each indication according to the new and FGs. During the follow-up period (mean: 6.9±5.2 years), the incidence of VF was higher in patients with Class IIa indication according to the NG (NG: 16/45 patients [35.6%] vs. FG: 16/104 patients [15.4%]), while the incidence of VF in patients with other than class I or IIa indication was similarly low in both guidelines (NG: 2/143 patients [1.4%] vs. FG: 2/84 patients [2.4%]).

CONCLUSIONS

This study validated the usefulness of the NG for risk stratification of BrS patients.

Brugada Syndrome: Clinical Features, Risk Stratification, and Management

In 1992, the Brugada brothers published a patient series of aborted sudden death, who were successfully resuscitated from ventricular fibrillation (VF). These patients had a characteristic coved ST-segment elevation in the right precordial leads on their 12-lead electrocardiogram with no apparent structural heart abnormality. This disease was referred to as “right bundle branch block, persistent ST-segment elevation, and sudden death syndrome.” The term Brugada syndrome (BrS) was first coined for this new arrhythmogenic entity in 1996. BrS is more prevalent in Southeast Asian ethnic groups and was considered a familial disease due to the presence of syncope and/or sudden deaths in several members of the same family, however, the genetic alteration was only noted in 1998. The genetic characterization of BrS has proven to be challenging. The most common and well-established BrS genotype involves loss-of-function mutations in the SCN5A gene, but only represents between 15% and 30% of the diagnosed patients. Patients with BrS can present with a range of symptoms which can include syncope, seizures, and nocturnal agonal breathing due to polymorphic ventricular tachycardia or VF. If these arrhythmias are sustained, sudden cardiac death may result. Despite the significant progress on the understanding of BrS over the last two decades, there remain a number of uncertainties and challenges; we present an update review on the subject.

Prognostic significance of a low T/R ratio in Brugada syndrome

OBJECTIVES

To determine the prognostic value of a low T/R ratio, defined as the amplitude ratio between the T waves and the R waves, in patients (pts) with a spontaneous type-1 Brugada pattern (SBT1).

BACKGROUND

Abnormalities of myocardial repolarization may play a key role in the initiation of ventricular fibrillation (VF) in Brugada syndrome (BrS). Recent studies have shown that the height of the T waves and the T/R ratio are inversely proportional to sudden cardiac arrest (SCA) risk in early repolarization syndrome and hypertrophic cardiomyopathy.

METHODS

In an international retrospective study, we reviewed 115 pts. (105 males, 91.3%). 45 had VF and/or SCA (38.7 ± 11.5 years old, all males), while 70 (49.3 ± 12.0 years, 10 women) remained free of ventricular arrhythmia. 6 ECG markers plus the T/R ratio in leads V5 & II were studied.

RESULTS

The T/R ratio among leads II & V5 was significantly lower in the VF/SCA group (0.24 [0.14; 0.38]vs. 0.34 [0.24; 0.45]; p = 0.006). 44.4% of pts. in the VF/SCA group had a lowest T/R ratio among leads II & V5 ≤ 0.17 compared to 11.4% in the non-VF/SCA group (p < 0.001). In multivariate analysis, a lowest T/R ratio among leads II & V5 ≤ 0.17 was independently associated with VF/SCA (OR 6.10, 95% CI 1.92-19.40; p = 0.002). Type 1 Brugada pattern in the peripheral leads (OR 10.78) and early repolarization (OR 3.60) were other independent markers of VF/SCA.

CONCLUSION

A low T/R ratio among leads II & V5 is an independent marker for VF/SCA risk in patients with type-1 Brugada pattern.

Outcome of Insertable Cardiac Monitors in Symptomatic Patients with Brugada Syndrome at Low Risk of Sudden Cardiac Death

INTRODUCTION

There is limited data on the experience with insertable cardiac monitors (ICMs) in patients with Brugada syndrome.

OBJECTIVE

To evaluate the outcome of ICM in symptomatic patients with Brugada syndrome who are at suspected low risk of sudden cardiac death (SCD).

METHODS

We conducted a prospective single-center cohort study including all symptomatic patients with Brugada syndrome who received an ICM (Reveal LINQ) between July 2014 and October 2019. The main indication for monitoring was to exclude ventricular arrhythmias as the cause of symptoms and to establish a symptom-rhythm relationship.

RESULTS

A total of 20 patients (mean age, 39 ± 12 years; 55% male) received an ICM during the study period. Nine patients (45%) had a history of syncope (presumed nonarrhythmogenic), and 5 patients had a recent syncope (<6 months). During a median follow-up of 32 months (interquartile range, 11-36 months), 3 patients (15%) experienced an episode of nonsustained ventricular arrhythmia. No patient died suddenly or experienced a sustained ventricular arrhythmia, and no patient had a recurrence of syncope. Overall, 17 patients (85%) experienced symptoms during follow-up, of whom 10 patients had an ICM-detected arrhythmia. In 4 patients (20%), the ICM-detected arrhythmia was an actionable event. ICM-guided management included antiarrhythmic drug therapy for symptomatic ectopic beats (n = 3), pulmonary vein isolation, and oral anticoagulation for atrial fibrillation (n = 1), electrophysiological study for risk stratification (n = 1), and pacemaker implantation for atrioventricular block (n = 1).

CONCLUSIONS

An ICM can be used to exclude ventricular arrhythmias in symptomatic patients with Brugada syndrome at low risk of SCD. Furthermore, an ICM-detected arrhythmia changed clinical management in 20% of patients.

The role of clinical assessment and electrophysiology study in Brugada syndrome patients with syncope

BACKGROUND

Cardiogenic syncope in Brugada syndrome (BrS) increases the risk of major events. Nevertheless, clinical differentiation between cardiogenic and vasovagal syncope can be challenging. We characterized the long-term incidence of major events in a large cohort of BrS patients who presented with syncope.

METHODS

From a total of 474 patients, syncope was the initial manifestation in 135 (28.5%) individuals (43.9 ± 13.9 years, 71.1% male). The syncope was classified prospectively as cardiogenic, vasovagal, or undefined if unclear characteristics were present. Clinical, electrocardiographic, genetic, and electrophysiologic features were analyzed. Cardiogenic syncope, sustained ventricular arrhythmias, and sudden death were considered major events in follow-up.

RESULTS

In 66 patients (48.9%), the syncope was cardiogenic; in 51 (37.8%), vasovagal and in 18 (13.3%); undefined. The electrophysiology study (EPS) inducibility was more frequent in patients with cardiogenic syncope and absent in all patients with undefined syncope (28 [53.8%] vs 5 [12.2%] vs 0 [0%]; P < .01). During follow-up (7.7 ± 5.6 years), only patients with cardiogenic syncope presented major events (16 [11.9%]). Among patients with inducible EPS, 7 (21.2%) presented major events (P = .04). The negative predictive value of the EPS for major events was 92.4%. The incidence rate of major events was 2.6% person-year. Parameters associated with major events included cardiogenic syncope (hazard ratio [HR] 6.3; 95% CI 1.1-10.4; P = .05), spontaneous type 1 electrocardiogram (HR 3.7; 95% CI 1.3-10.5; P = .01), and inducible EPS (HR 2.8; 95% CI 1.1-8.8; P = .05).

CONCLUSIONS

An accurate syncope classification is crucial in BrS patients for risk stratification. In patients with syncope of unclear characteristics, the EPS may be helpful to prevent unnecessary implantable cardioverter defibrillators.

Brugada Syndrome: Clinical Care Amidst Pathophysiological Uncertainty

Brugada syndrome (BrS) is a complex clinical entity with ongoing conjecture regarding its genetic basis, underlying pathophysiology, and clinical management. Within this paradigm of uncertainty, clinicians are faced with the challenge of caring for patients with this uncommon but potentially fatal condition. This article reviews the current understanding of BrS and highlights the "known unknowns" to reinforce the need for flexible clinical practice in parallel with ongoing scientific discovery.

Insertable cardiac monitors: current indications and devices

INTRODUCTION

Recurrent unexplained syncope is a well-established indication for an insertable cardiac monitor (ICM). Recently, the indications for an ICM have been expanded.

AREAS COVERED

This review article discusses the current indications for ICMs and gives an overview of the latest generation of commercially available ICMs.

EXPERT COMMENTARY

The 2018 ESC Syncope guidelines have expanded the indications for an ICM to patients with inherited cardiomyopathy, inherited channelopathy, suspected unproven epilepsy, and unexplained falls. ICMs are also increasingly used for the detection of subclinical atrial fibrillation (AF) in patients with cryptogenic stroke. Whether treatment of subclinical AF (SCAF) with oral anticoagulation prevents recurrent stroke is yet unknown. The current generation of ICMs are smaller, easier to implant, have better diagnostics, and are capable of remote monitoring. The Reveal LINQ (Medtronic) is the smallest ICM and has the most extensive performance and clinical data. The BioMonitor 2 (Biotronik) is the largest ICM but has excellent R-wave amplitudes, longest longevity, and reliable remote monitoring. The Confirm Rx (Abbott) is capable to provide mobile data transmission enabled by a smartphone app. Future generation of ICMs will incorporate heart failures indices to facilitate remote monitoring of heart failure patients.

Gender Differences in Prognosis and Risk Stratification of Brugada Syndrome: A Pooled Analysis of 4,140 Patients From 24 Clinical Trials

Background: Male gender has been consistently shown to be a risk factor for a greater number of arrhythmic events in patients with Brugada Syndrome (BrS). However, there have been no large-scale comprehensive pooled analyses to statistically and systematically verify this association. Therefore, we conducted a pooled analysis on gender differences in prognosis and risk stratification of BrS with a largest sample capacity at present.

Methods: We searched PubMed, Embase, Medline, Cochrane Library databases, Chinese National Knowledge Infrastructure, and Wanfang Data for relevant studies published from 2002 to 2017. The prognosis and risk stratification of BrS and risk factors were then investigated and evaluated according to gender.

Results: Twenty-four eligible studies involving 4,140 patients were included in the analysis. Male patients (78.1%) had a higher risk of arrhythmic events than female patients (95% confidence interval: 1.46–2.91, P < 0.0001). Among the male population, there were statistical differences between symptomatic patients and asymptomatic patients (95% CI: 2.63–7.86, P < 0.00001), but in the female population, no statistical differences were found. In the female subgroup, electrophysiological study (EPS) positive patients had a tendency toward a higher risk of arrhythmic events than EPS-negative patients (95% CI: 0.93–29.77, P = 0.06).

Conclusions: Male patients are at a higher risk of arrhythmic events than female patients. Within the male population, symptomatic patients have a significantly higher risk profile compared to asymptomatic patients, but no such differences are evident within the female population. Consequently, in the female population, the risk of asymptomatic patterns cannot be underestimated.

[Syncopes and channelopathies]

Syncope can be the first manifestation of cardiac channelopathies, namely Brugada syndrome, long QT syndrome, short QT syndrome and catecholaminergic polymorphic ventricular tachycardia (CPVT). Patients affected by these rare diseases are at increased risk for sudden cardiac death due to ventricular tachyarrhythmias and require specific therapy and follow-up. As syncope is common in the general population, only few cases are caused by an underlying channelopathy. Nevertheless, the diagnosis should be considered in young patients with structurally normal hearts, especially if the history of syncope is typical for an arrhythmogenic cause, in the presence of characteristic echocardiogram (ECG) patterns, and if there is a family history of channelopathies or sudden cardiac death. On the other hand, syncope plays an important role in the management of patients with diagnosed channelopathies, as they may indicate an increased risk for sudden cardiac death. The predictive value and consequences for treatment vary between the different channelopathies. However, data on this issue are scarce due to the low prevalence of these diseases. This review highlights typical findings in the medical history and diagnostic tests that may point towards an underlying channelopathy in patients with syncope. It also discusses the prognostic and therapeutic implications of a history of syncope in patients with known channelopathies.

Athletes with channelopathy may be eligible to play

The European and Bethesda recommendations roughly state that any athlete with channelopathy is not eligible to participate in sports on a presumed risk of potentially life-threatening ventricular tachycardia or fibrillation. However, eligibility decision-making on a presumed risk of ventricular tachycardia or fibrillation is debatable. Channelopathies are primary electrical cardiac disorders and are usually transmitted as an autosomal dominant trait. Some of the channelopathies are potentially fatal in relation to exercise and predispose to life-threatening cardiac arrhythmias including ventricular tachycardia or fibrillation. Exercise, swimming, body heating and electrolyte depletion can all act as a trigger of ventricular tachycardia or fibrillation in channelopathy. However, new research mentioned a very low incidence of ventricular tachycardia or fibrillation in athletes with channelopathy challenging the decision of disqualification. Recently, the American recommendations for sports participation in athletes with a cardiovascular disorder have updated their eligibility decision-making.In this manuscript we describe the signature features of the electrocardiogram changes in channelopathies and we argue that new research data should allow for the introduction of more liberal eligibility decision-making for sports participation in athletes with channelopathy, not only in the United States but also in European countries.

Syncope and the risk of sudden cardiac death: Evaluation, management, and prevention

Syncope is a clinical syndrome defined as a relatively brief self-limited transient loss of consciousness (TLOC) caused by a period of inadequate cerebral nutrient flow. Most often the trigger is an abrupt drop of systemic blood pressure. True syncope must be distinguished from other common non-syncope conditions in which real or apparent TLOC may occur such as seizures, concussions, or accidental falls. The causes of syncope are diverse, but in most instances, are relatively benign (e.g., reflex and orthostatic faints) with the main risks being accidents and/or injury. However, in some instances, syncope may be due to more worrisome conditions (particularly those associated with cardiac structural disease or channelopathies); in such circumstances, syncope may be an indicator of increased morbidity and mortality risk, including sudden cardiac death (SCD). Establishing an accurate basis for the etiology of syncope is crucial in order to initiate effective therapy. In this review, we focus primarily on the causes of syncope that are associated with increased SCD risk (i.e., sudden arrhythmic cardiac death), and the management of these patients. In addition, we discuss the limitations of our understanding of SCD in relation to syncope, and propose future studies that may ultimately address how to improve outcomes of syncope patients and reduce SCD risk.

Brugada syndrome: A general cardiologist's perspective

Brugada syndrome (BrS) is one of the commonest inherited primary arrhythmia syndromes typically presenting with arrhythmic syncope or sudden cardiac death (SCD) due to polymorphic ventricular tachycardia and ventricular fibrillation precipitated by vagotonia or fever in apparently healthy adults, less frequently in children. The prevalence of the syndrome (0.01%-0.3%) varies among regions and ethnicities, being the highest in Southeast Asia. BrS is diagnosed by the "coved type" ST-segment elevation≥2mm followed by a negative T-wave in ≥1 of the right precordial leads V₁-V₂. The typical electrocardiogram in BrS is often concealed by fluctuations between normal, non-diagnostic and diagnostic ST-segment pattern in the same patient, thus hindering the diagnosis. Presently, the majority of BrS patients is incidentally diagnosed, and may remain asymptomatic for their lifetime. However, BrS is responsible for 4-12% of all SCDs and for ~20% of SCDs in patients with structurally normal hearts. Arrhythmic risk is the highest in SCD survivors and in patients with spontaneous BrS electrocardiogram and arrhythmic syncope, but risk stratification for SCD in asymptomatic subjects has not yet been fully defined. Recent achievements have expanded our understanding of the genetics and electrophysiological mechanisms underlying BrS, while radiofrequency catheter ablation may be an effective new approach to treat ventricular tachyarrhythmias in BrS patients with arrhythmic storms. The present review summarizes our contemporary understanding and recent advances in the inheritance, pathophysiology, clinical assessment and treatment of BrS patients.

Brugada Syndrome:Risk Stratification And Management

The Brugada syndrome (BrS) is an arrhythmogenic disease associated with an increased risk of ventricular fibrillation and sudden cardiac death. The risk stratification and management of BrS patients, particularly of asymptomatic ones, still remains challenging. A previous history of aborted sudden cardiac death or arrhythmic syncope in the presence of spontaneous type 1 ECG pattern of BrS phenotype appear to be the most reliable predictors of future arrhythmic events. Several other ECG parameters have been proposed for risk stratification. Among these ECG markers, QRS-fragmentation appears very promising. Although the value of electrophysiological study still remains controversial, it appears to add important information on risk stratification, particularly when incorporated in multiparametric scores in combination with other known risk factors. The present review article provides an update on the pathophysiology, risk stratification and management of patients with BrS.

The Diagnosis, Risk Stratification, and Treatment of Brugada Syndrome

BACKGROUND

Brugada syndrome (BrS) is among the more common familial arrhythmia syndromes, with an estimated prevalence of 1 to 5 per 10 000 persons. It is characterized by a right ventricular conduction delay, dynamic or persistent ST-segment elevations in the precordial leads V1-3 , and an elevated risk of syncope and sudden cardiac death in young adults without structural heart disease.

METHODS

This article is based on original and review articles on BrS that appeared in English from 2010 onward and were retrieved by a selective search in PubMed, with special attention to international consensus publications on inherited arrhythmogenic diseases.

RESULTS

According to the new diagnostic criteria, the diagnosis of BrS requires typical ECG changes in only one precordial lead. This will likely increase sensitivity, but may also lead to an increase in asymptomatic patients. Established risk markers include sudden cardiac arrest and a spontaneous type 1 ECG with arrhythmic syncope. Patients with these findings benefit from the implantation of a cardioverter-defibrillator. There is no validated algorithm for risk stratification of asymptomatic patients. Because of the low prevalence of BrS, there have been no randomized controlled trials (RCTs) in this disease, and all recommendations are based on expert opinion. BrS is usually inherited in an autosomal dominant manner. Recently discovered gene polymorphisms modify the risk of BrS, challenging the conception of BrS as a monogenetic disease. Electro-anatomic mapping studies have revealed, for the first time, an arrhythmogenic substrate over the right ventricular outflow tract in BrS patients.

CONCLUSION

BrS is one important differential diagnosis to consider in patients presenting with syncope or sudden cardiac arrest. The goal of current research is to achieve a deeper understanding of the genetic and electrophysiological changes underlying BrS. Further insights in these areas will probably enable better risk stratification of asymptomatic BrS patients in the future.