Programmed Ventricular Stimulation for Risk Stratification in the Brugada Syndrome: A Pooled Analysis

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.

The BrAID study protocol: integration of machine learning and transcriptomics for brugada syndrome recognition

BACKGROUND

Type 1 Brugada syndrome (BrS) is a hereditary arrhythmogenic disease showing peculiar electrocardiographic (ECG) patterns, characterized by ST-segment elevation in the right precordial leads, and risk of Sudden Cardiac Death (SCD). Furthermore, although various ECG patterns are described in the literature, different individual ECG may show high-grade variability, making the diagnosis problematic. The study aims to develop an innovative system for an accurate diagnosis of Type 1 BrS based on ECG pattern recognition by Machine Learning (ML) models and blood markers analysis trough transcriptomic techniques.

METHODS

The study is structured in 3 parts: (a) a retrospective study, with the first cohort of 300 anonymized ECG obtained in already diagnosed Type 1 BrS (75 spontaneous, 150 suspected) and 75 from control patients, which will be processed by ML analysis for pattern recognition; (b) a prospective study, with a cohort of 11 patients with spontaneous Type 1 BrS, 11 with drug-induced Type 1 BrS, 11 suspected BrS but negative to Na + channel blockers administration, and 11 controls, enrolled for ECG ML analysis and blood collection for transcriptomics and microvesicles analysis; (c) a validation study, with the third cohort of 100 patients (35 spontaneous and 35 drug-induced BrS, 30 controls) for ML algorithm and biomarkers testing.

DISCUSSION

The BrAID system will help clinicians improve the diagnosis of Type 1 BrS by using multiple information, reducing the time between ECG recording and final diagnosis, integrating clinical, biochemical and ECG information thus favoring a more effective use of available resources. Trial registration Clinical Trial.gov, NCT04641585. Registered 17 November 2020, https://clinicaltrials.gov/ct2/show/NCT04641585.

Brugada syndrome

Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome that causes a heightened risk for ventricular tachyarrhythmias and sudden cardiac death. BrS is characterised by a coved ST-segment elevation in right precordial leads. The prevalence is estimated to range between 1 in 5,000 to 1 in 2,000 in different populations, with the highest being in Southeast Asia and in males. More than 18 genes associated with BrS have been discovered and recent evidence has suggested a complex polygenic mode of inheritance with multiple common and rare genetic variants acting in concert to produce the BrS phenotype. Diagnosis of BrS in patients currently relies on presentation with a type-1 Brugada pattern on ECG either spontaneously or following a drug provocation test using a sodium channel blocker. Risk assessment in patients diagnosed with BrS is controversial, especially with regard to the predictive value of programmed electrical stimulation and novel ECG parameters, such as QRS fragmentation. The first line of BrS therapy remains an implantable cardioverter defibrillator (ICD), although radiofrequency catheter ablation has been shown to be an effective option in patients with contraindications for an ICD. True BrS can be unmasked on ECG in susceptible individuals by monitoring factors such as fever, and this has been recently evident in several patients infected with the 2019 novel coronavirus (COVID-19). Aggressive antipyretic therapy and regular ECG monitoring until fever resolves are current recommendations to help reduce the arrhythmic risk in these COVID-19 patients. In this review, we summarise the current knowledge on the epidemiology, pathophysiology, genetics, clinical diagnosis, risk stratification and treatment of patients with BrS, with special emphasis on COVID-19 comorbidity.

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.

Validation of multiparametric approaches for the prediction of sudden cardiac death in patients with Brugada syndrome and electrophysiological study

INTRODUCTION AND OBJECTIVES

Multiparametric scores have been designed for better risk stratification in Brugada syndrome (BrS). We aimed to validate 3 multiparametric approaches (the Delise score, Sieira score and the Shanghai BrS Score) in a cohort with Brugada syndrome and electrophysiological study (EPS).

METHODS

We included patients diagnosed with BrS and previous EPS between 1998 and 2019 in 23 hospitals. C-statistic analysis and Cox proportional hazard regression models were used.

RESULTS

A total of 831 patients were included (mean age, 42.8±13.1; 623 [75%] men; 386 [46.5%] had a type 1 electrocardiogram (ECG) pattern, 677 [81.5%] were asymptomatic, and 319 [38.4%] had an implantable cardioverter-defibrillator). During a follow-up of 10.2±4.7 years, 47 (5.7%) experienced a cardiovascular event. In the global cohort, a type 1 ECG and syncope were predictive of arrhythmic events. All risk scores were significantly associated with events. The discriminatory abilities of the 3 scores were modest (particularly when these scores were evaluated in asymptomatic patients). Evaluation of the Delise and Sieira scores with different numbers of extra stimuli (1 or 2 vs 3) did not substantially improve the event prediction c-index.

CONCLUSIONS

In BrS, classic risk factors such as ECG pattern and previous syncope predict arrhythmic events. The predictive capabilities of the EPS are affected by the number of extra stimuli required to induce ventricular arrhythmias. Scores combining clinical risk factors with EPS help to identify the populations at highest risk, although their predictive abilities remain modest in the general BrS population and in asymptomatic patients.

A Deep Learning-enabled Electrocardiogram Model for the Identification of a Rare Inherited Arrhythmia: Brugada Syndrome

BACKGROUND

Brugada syndrome is a major cause of sudden cardiac death in young people with a distinctive electrocardiogram (ECG) feature. We aimed to develop a deep learning-enabled ECG model for automatic screening Brugada syndrome to identify these patients at an early time, thus allowing for life-saving therapy.

METHODS

A total of 276 ECGs with a type 1 Brugada ECG pattern (276 type 1 Brugada ECGs and another randomly retrieved 276 non-Brugada type ECGs for one to one allocation) were extracted from the hospital-based ECG database for a two-stage analysis with a deep learning model. After trained network for identifying right bundle branch block pattern, we transferred the first-stage learning to the second task to diagnose the type 1 Brugada ECG pattern. The diagnostic performance of the deep learning model was compared to that of board-certified practicing cardiologists. The model was further validated in the independent ECG dataset, collected from the hospitals in Taiwan and Japan.

RESULTS

The diagnoses by the deep learning model (AUC: 0.96, sensitivity: 88.4%, specificity: 89.1%) were highly consistent with the standard diagnoses (Kappa coefficient: 0.78). However, the diagnoses by the cardiologists were significantly different from the standard diagnoses, with only moderate consistency (Kappa coefficient: 0.63). In the independent ECG cohort, the deep learning model still reached a satisfactory diagnostic performance (AUC 0.89, sensitivity: 86.0%, specificity: 90.0%).

CONCLUSIONS

We presented the first deep learning-enabled ECG model for diagnosing Brugada syndrome, which appears to be a robust screening tool with a diagnostic potential rivaling trained physicians.

Comparative Effectiveness of Implantable Defibrillators for Asymptomatic Brugada Syndrome: A Decision-Analytic Model

Background Optimal management of asymptomatic Brugada syndrome (BrS) with spontaneous type I electrocardiographic pattern is uncertain. Methods and Results We developed an individual-level simulation comprising 2 000 000 average-risk individuals with asymptomatic BrS and spontaneous type I electrocardiographic pattern. We compared (1) observation, (2) electrophysiologic study (EPS)-guided implantable cardioverter-defibrillator (ICD), and (3) upfront ICD, each using either subcutaneous or transvenous ICD, resulting in 6 strategies tested. The primary outcome was quality-adjusted life years (QALYs), with cardiac deaths (arrest or procedural-related) as a secondary outcome. We varied BrS diagnosis age and underlying arrest rate. We assessed cost-effectiveness at $100 000/QALY. Compared with observation, EPS-guided subcutaneous ICD resulted in 0.35 QALY gain/individual and 4130 cardiac deaths avoided/100 000 individuals, and EPS-guided transvenous ICD resulted in 0.26 QALY gain and 3390 cardiac deaths avoided. Compared with observation, upfront ICD reduced cardiac deaths by a greater margin (subcutaneous ICD, 8950; transvenous ICD, 6050), but only subcutaneous ICD improved QALYs (subcutaneous ICD, 0.25 QALY gain; transvenous ICD, 0.01 QALY loss), and complications were higher. ICD-based strategies were more effective at younger ages and higher arrest rates (eg, using subcutaneous devices, upfront ICD was the most effective strategy at ages 20-39.4 years and arrest rates >1.37%/year; EPS-guided ICD was the most effective strategy at ages 39.5-51.3 years and arrest rates 0.47%-1.37%/year, and observation was the most effective strategy at ages >51.3 years and arrest rates <0.47%/year). EPS-guided subcutaneous ICD was cost-effective ($80 508/QALY). Conclusions Device-based approaches (with or without EPS risk stratification) can be more effective than observation among selected patients with asymptomatic BrS. BrS management should be tailored to patient characteristics.

Role of the rabbit whole-heart model for electrophysiologic safety pharmacology of non-cardiovascular drugs

Plenty of non-cardiovascular drugs alter cardiac electrophysiology and may ultimately lead to life-threatening arrhythmias. In clinical practice, measuring the QT interval as a marker for the repolarization period is the most common tool to assess the electrophysiologic safety of drugs. However, the sole measurement of the QT interval may be insufficient to determine the proarrhythmic risk of non-cardiovascular agents. Several other markers are considered in pre-clinical safety testing to determine potential harm on cardiac electrophysiology. Besides measuring typical electrophysiologic parameters such as repolarization duration, whole-heart models allow the determination of potential predictors for proarrhythmia. Spatial and temporal heterogeneity as well as changes of shape of the action potential can be easily assessed. In addition, provocation manoeuvers (either by electrolyte imbalances or programmed pacing protocols) may induce sustained arrhythmias and thereby determine ventricular vulnerability to arrhythmias. Compared with the human heart, the rabbit heart possesses a similar distribution of ion currents that govern cardiac repolarization, resulting in a rectangular action potential configuration in both species. In addition, similar biophysical properties of rabbit and human cardiac ion channels lead to a comparable pharmacologic response in human and rabbit hearts. Of note, arrhythmia patterns resemble in both species due to the similar effective size of human and rabbit hearts. Thus, the rabbit heart is particularly suitable for testing the electrophysiologic safety of drugs. Several experimental setups have been developed for studying cardiac electrophysiology in rabbits, ranging from single cell to tissue preparations, whole-heart setups, and in vivo models.

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.

Common variants in SCN10A gene associated with Brugada syndrome

BACKGROUND

Genome-wide association studies indicate that SCN10A plays an important role in cardiac electrophysiology. Common and rare SCN10A variants are suggested to contribute to Brugada Syndrome (BrS), an inherited channelopathy resulting from genetic-determined loss-of-function in cardiac sodium channel. This study sought to characterize the role of SCN10A common variants in BrS.

METHODS AND RESULTS

Clinical and genetic analyses were performed in 197 patients diagnosed with BrS. Baseline ECG parameters were evaluated in patients carrying each of four common variants associated with BrS. Cellular electrophysiological study was performed in SCN5A-SCN10A co-transfected TSA201 cells to investigate the possible electrophysiological characteristics of the allele of rs6795970, which displayed the most significant association with BrS. Four SCN10A common variants (rs7630989, rs57326399, rs6795970, rs12632942) displayed significant association with BrS susceptibility. There were no evident associations between baseline ECG parameters in BrS patients and the different genotypes of the four variants. Rs6795970 (V1073) was strongly associated with a risk for BrS, which suggests the different electrophysiological characters between these two alleles. Functional study showed a positive shift in steady-state activation (V1/2: -62.2 ± 2.6 vs. -53.5 ± 1.6 for A1073 and V1073 group, respectively; P < 0.05) and slower recovery from inactivation in mutant SCN5A-SCN10A co-transfected cells with, which contribute to the slow conduction in BrS patients with rs6795970.

CONCLUSIONS

SCN10A common variants are associated with increased susceptibility to BrS. An allele rs6795970 (V1073) increases the risk for BrS. The electrophysiological changes in a positive shift in steady-state activation and slower recovery from inactivation by SCN10A-V1073 contribute to this variant associated BrS.

Diagnosis, family screening, and treatment of inherited arrhythmogenic diseases in Europe: results of the European Heart Rhythm Association Survey

The spectrum of inherited arrhythmogenic diseases (IADs) includes disorders without overt structural abnormalities (i.e. primary inherited arrhythmia syndromes) and structural heart diseases (i.e. arrhythmogenic ventricular cardiomyopathy, hypertrophic cardiomyopathy). The aim of this European Heart Rhythm Association (EHRA) survey was to evaluate current clinical practice and adherence to 2015 European Society of Cardiology Guidelines regarding the management of patients with IADs. A 24-item centre-based online questionnaire was presented to the EHRA Research Network Centres and the European Cardiac Arrhythmia Genetics Focus Group members. There were 46 responses from 20 different countries. The survey revealed that 37% of centres did not have any dedicated unit focusing on patients with IADs. Provocative drug challenges were widely used to rule-out Brugada syndrome (BrS) (91% of centres), while they were used in a minority of centres during the diagnostic assessment of long-QT syndrome (11%), early repolarization syndrome (12%), or catecholaminergic polymorphic ventricular tachycardia (18%). While all centres advised family clinical screening with electrocardiograms for all first-degree family members of patients with IADs, genetic testing was advised in family members of probands with positive genetic testing by 33% of centres. Sudden cardiac death risk stratification was straightforward and in line with current guidelines for hypertrophic cardiomyopathy, while it was controversial for other diseases (i.e. BrS). Finally, indications for ventricular mapping and ablation procedures in BrS were variable and not in agreement with current guidelines in up to 54% of centres.

Indication and prognostic significance of programmed ventricular stimulation in asymptomatic patients with Brugada syndrome

AIMS

To establish the indication for programmed ventricular stimulation (PVS) for asymptomatic patients with Brugada syndrome (BrS), we evaluated the prognostic significance of PVS based on abnormal electrocardiogram (ECG) markers.

METHODS AND RESULTS

One hundred and twenty-five asymptomatic patients with BrS were included. We performed PVS at two sites of the right ventricle with up to three extrastimuli [two pacing cycle lengths and minimum coupling interval (MCI) of 180 ms]. We followed the patients for 133 months and evaluated ventricular fibrillation (VF) events. Fragmented QRS (fQRS) and Tpeak-Tend (Tpe) interval were evaluated as ECG markers for identifying high-risk patients. Fragmented QRS and long Tpe interval (≥100 ms) were observed in 66 and 37 patients, respectively. Ventricular fibrillation was induced by PVS in 60 patients. During follow-up, 10 patients experienced VF events. Fragmented QRS, long Tpe interval, and PVS-induced VF with an MCI of 180 ms or up to two extrastimuli were associated with future VF events (fQRS: P = 0.015, Tpe ≥ 100 ms: P = 0.038, VF induction: P < 0.001). However, PVS-induced VF with an MCI of 200 ms was less specific (P = 0.049). The frequencies of ventricular tachyarrhythmia events during follow-up were 0%/year with no ECG markers and 0.1%/year with no VF induction. The existence of two ECG factors with induced VF was strongly associated with future VF events (event rate: 4.4%/year, P < 0.001), and the existence of one ECG factor with induced VF was also associated (event rate: 1.3%/year, P = 0.011).

CONCLUSION

We propose PVS with a strict protocol for asymptomatic patients with fQRS and/or long Tpe interval to identify high-risk patients.

A case series of Brugada syndrome with a novel mutation in the ankyrin-B gene: an unusual unmasking in acute myocarditis

BACKGROUND

Brugada syndrome (BrS) is a genetically heterogeneous channelopathy that may lead to sudden death. We report a novel mutation of the ankyrin-B gene that is probably related to the occurrence of BrS in two brothers.

CASE SUMMARY

First, we present the case of a 27-year-old male who was admitted to the hospital with acute myocarditis. The patient showed left ventricular dysfunction and was given carvedilol. Six days later, while asymptomatic and afebrile, the patient exhibited an electrocardiogram (ECG) with repolarization 'saddleback' ST changes in V2. A procainamide provocative test was performed with a response for Type 1 Brugada ECG pattern. Genetic testing revealed a novel mutation, c.5418T>A (+/-) (p.His1806Gln), in the ankyrin-B gene encoding. His 34 years old brother had an ECG J point elevation in leads V1 and V2 of 1 mm not fulfilling diagnostic criteria for Brugada ECG pattern. He also experienced arrhythmia-related syncope. Flecainide provocation test changed ECG towards a Type 1 Brugada pattern. A subcutaneous implantable defibrillator (ICD) was implanted. Patient 1 remains asymptomatic while Patient 2 experienced an appropriate ICD shock during follow-up.

DISCUSSION

In this case series, two brothers with BrS exhibited the same mutation of the ankyrin-B gene. Ankyrin-B is associated with the stability of plasma membrane proteins in the voltage-gated ion channels. Our finding provides a foundation for further investigation of this mutation in relation to BrS. Moreover, the timing of its presentation raises concerns as to whether myocarditis or beta-blockers are associated with the presentation of BrS ECG.

Robustness and relevance of predictive score in sudden cardiac death for patients with Brugada syndrome

AIMS

Risk stratification of sudden cardiac arrest (SCA) in Brugada syndrome (Brs) remains the main challenge for physicians. Several scores have been suggested to improve risk stratification but never replicated. We aim to investigate the accuracy of the Brs risk scores.

METHODS AND RESULTS

A total of 1613 patients [mean age 45 ± 15 years, 69% male, 323 (20%) symptomatic] were prospectively enrolled from 1993 to 2016 in a multicentric database. All data described in the risk score were double reviewed for the study. Among them, all patients were evaluated with Shanghai score and 461 (29%) with Sieira score. After a mean follow-up of 6.5 ± 4.7 years, an arrhythmic event occurred in 75 (5%) patients including 16 SCA, 11 symptomatic ventricular arrhythmia, and 48 appropriate therapies. Predictive capacity of the Shanghai score (n = 1613) and the Sieira (n = 461) score was, respectively, estimated by an area under the curve of 0.73 (0.67-0.79) and 0.71 (0.61-0.81). Considering Sieira score, the event rate at 10 years was significantly higher with a score of 5 (26.4%) than with a score of 0 (0.9%) or 1 (1.1%) (P < 0.01). No statistical difference was found in intermediate-risk patients (score 2-4). The Shanghai score does not allow to better stratify the risk of SCA.

CONCLUSIONS

In the largest cohort of Brs patient ever described, risk scores do not allow stratifying the risk of arrhythmic event in intermediate-risk patient.

Catheter Ablation for Brugada Syndrome

We report a case of catheter ablation of Brugada syndrome in a patient with refractory ventricular fibrillation despite quinidine therapy. We performed epicardial substrate mapping, which identified an area of abnormal fractionated, prolonged electrogram in the anterior right ventricular outflow tract. Warm saline infusion into the pericardial space induced further delay of the local electrogram, consistent with Brugada syndrome physiology. Coronary angiography confirmed that the area was distant from major coronary arteries. Ablation was performed in this area, which eliminated local abnormal electrograms and led to the disappearance of coved-type ST elevation in V1–V2. No ventricular fibrillation had recurred by five months of follow-up.

Standard ECG in Brugada Syndrome as a Marker of Prognosis: From Risk Stratification to Pathophysiological Insights

Background

The 12‐lead ECG plays a key role in the diagnosis of Brugada syndrome (BrS). Since the spontaneous type 1 ECG pattern was first described, several other ECG signs have been linked to arrhythmic risk, but results are conflicting.

Methods and Results

We performed a systematic review to clarify the associations of these specific ECG signs with the risk of syncope, sudden death, or equivalents in patients with BrS. The literature search identified 29 eligible articles comprising overall 5731 patients. The ECG findings associated with an incremental risk of syncope, sudden death, or equivalents (hazard ratio ranging from 1.1–39) were the following: localization of type 1 Brugada pattern (in V2 and peripheral leads), first‐degree atrioventricular block, atrial fibrillation, fragmented QRS, QRS duration >120 ms, R wave in lead aVR, S wave in L1 (≥40 ms, amplitude ≥0.1 mV, area ≥1 mm²), early repolarization pattern in inferolateral leads, ST‐segment depression, T‐wave alternans, dispersion of repolarization, and Tzou criteria.

Conclusions

At least 12 features of standard ECG are associated with a higher risk of sudden death in BrS. A multiparametric risk assessment approach based on ECG parameters associated with clinical and genetic findings could help improve current risk stratification scores of patients with BrS and warrants further investigation.

Registration

URL: https://www.crd.york.ac.uk/prospero/. Unique identifier: CRD42019123794.

Precision Medicine Approaches to Cardiac Arrhythmias: JACC Focus Seminar 4/5

In the initial 3 papers in this Focus Seminar series, the fundamentals and key concepts of precision medicine were reviewed, followed by a focus on precision medicine in the context of vascular disease and cardiomyopathy. For the remaining 2 papers, we focus on precision medicine in the context of arrhythmias. Specifically, in this fourth paper we focus on long QT syndrome, Brugada syndrome, and atrial fibrillation. The final (fifth) paper will deal with catecholaminergic polymorphic ventricular tachycardia. These arrhythmias represent a spectrum of disease ranging from common to relatively rare, with very different genetic and environmental causative factors, and with differing clinical manifestations that range from almost no consequences to lethality in childhood or adolescence if untreated. Accordingly, the emerging precision medicine approaches to these arrhythmias vary significantly, but several common themes include increased use of genetic testing, avoidance of triggers, and personalized risk stratification to guide the use of arrhythmia-specific therapies.

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.

Clinical significance of inferolateral early repolarisation and late potentials in children with Brugada Syndrome

INTRODUCTION

The clinical utility of inferolateral early repolarisation (ER) and late potentials (LP) in children with Brugada Syndrome (BrS) has not been previously evaluated. The aim of this study was to determine the prevalence of electrocardiographic (ECG) abnormalities in children with BrS, and to investigate their relationship with clinical outcomes.

METHODS

43 patients with BrS and 47 controls aged ≤18 undergoing systematic clinical and ECG evaluation, including signal-averaged ECG (SAECG) and pharmacological provocation testing, between 2003 and 2019 were included.

RESULTS

Four patients with BrS (9%) presented with a spontaneous type 1 Brugada pattern; the remaining 39 (91%) were diagnosed following ajmaline provocation testing. Twelve BrS patients (28%) had late potentials (LP) on SAECG compared to 1 (2%) in controls (p = 0.001). LP were more common in 5 patients with a high-risk phenotype (60% vs 24%) but this was not statistically significant. Twelve patients with BrS (28%) had inferolateral early repolarisation (ER) and 2 (5%) had fractionated QRS (f-QRS), but there were no statistically-significant differences with controls in these parameters. A significant arrhythmia (non-sustained ventricular tachycardia or atrial fibrillation) was seen in 4 patients (9%).

CONCLUSIONS

This study shows a high prevalence of SAECG abnormalities in children with BrS compared with controls, but this was not significantly associated with a high-risk phenotype.

Brugada syndrome clinical update

Brugada syndrome (BrS) was initially described in southeast Asians with a structurally normal heart presenting with polymorphic ventricular tachycardia and fibrillation. This condition is marked by J-point elevation ≥ 2 mm with coved-type ST segment elevation followed by negative T wave inversions in at least one precordial lead (V1 or V2) when other etiologies have been excluded. These changes on electrocardiogram (EKG) can either be spontaneous or manifest after sodium channel blockade. The worldwide prevalence of BrS is about 0.4%; however, it is higher in the Asian population at 0.9%. This article will review the current hypotheses regarding the pathophysiology, spectrum of clinical presentation, strategies for prevention of sudden cardiac death and the treatment for recurrent arrhythmias in BrS.

Long-term prognosis in patients with non-type 1 Brugada electrocardiogram: Results from a large Japanese cohort of idiopathic ventricular fibrillation

Background

Brugada syndrome (BrS) is diagnosed in patients with ST‐segment elevation with spontaneous, drug‐induced, or fever‐induced type 1 morphology. Prognosis in type 2 or 3 Brugada electrocardiogram (Br‐ECG) patients remains unknown. The purpose of this study is to evaluate long‐term prognosis in non‐type 1 Br‐ECG patients in a large Japanese cohort of idiopathic ventricular fibrillation (The Japan Idiopathic Ventricular Fibrillation Study [J‐IVFS]).

Methods

From 567 patients with Br‐ECG in J‐IVFS, a total of 28 consecutive non‐type 1 patients who underwent programmed electrical stimulation (PES) (median age: 58 years, all male, previous sustained ventricular tachyarrhythmias [VTs] 1, syncope 11, asymptomatic 16) were enrolled. Cardiac events (CEs: sudden cardiac death or sustained VT/ventricular fibrillation) during the follow‐up period were examined.

Results

During a median follow‐up of 136 months, four patients (14%) had CEs. None of patients with PES‐ have experienced CEs. There was no statistically significant clinical risk factor for the development of CEs. Using the Kaplan–Meier method, the event‐free rate significantly decreased in a group with all 3 risk factors (symptom, wide QRS complex in lead V₂, and positive PES) (p = .01).

Conclusions

Our study revealed long‐term prognosis in patients with non‐type 1 Br‐ECG. The combination analysis of these risk factors may be useful for the risk stratification of CEs in non‐type 1 Br‐ECG patients. The present study suggests that the patients with all these parameters showed high risk for CEs and need to be carefully followed.

Risk stratification in asymptomatic patients with Brugada syndrome: Utility of multiple risk factor combination rather than programmed electrical stimulation

BACKGROUND

The prognostic value of programmed electrical stimulation (PES) in Brugada syndrome (BrS) remains controversial. Asymptomatic BrS patients generally have a better prognosis than those with symptoms. The purpose of this study was to evaluate the value of nonaggressive PES with up to two extra stimuli and predict clinical factors for risk stratification in asymptomatic BrS patients.

METHODS

The study enrolled 193 consecutive asymptomatic BrS patients with type 1 ECG (mean age: 50 ± 13 years, 180 males) who underwent PES using a nonaggressive uniform protocol. Cardiac events (CEs: sudden cardiac death or ventricular tachyarrhythmia) during the follow-up period were examined.

RESULTS

During a mean follow-up of 101 ± 48 months, seven asymptomatic patients (3.6%) had a CE. The incidence of CEs was not different between patients with and without inducible ventricular tachyarrhythmia by PES (p = .51). The clinical significance of risk factor combinations, including spontaneous type 1 ECG, family history of sudden cardiac death, QRS duration in lead V₂ , and presence of J wave, was evaluated. Using the Kaplan-Meier method according to the number of risk factors, the prevalence of CE in patients with three or four risk factors was determined to be significantly higher than in those with one risk factor (p = .02 and p = .004, respectively).

CONCLUSIONS

The present study suggests that inducibility of ventricular tachyarrhythmia does not predict future CEs in asymptomatic BrS patients. Combination analysis of the other four clinical risk parameters may be effective for risk assessment.

Long-term prognosis of women with Brugada syndrome and electrophysiological study

BACKGROUND

A male predominance in Brugada syndrome (BrS) has been widely reported, but scarce information on female patients with BrS is available.

OBJECTIVE

The purpose of this study was to investigate the clinical characteristics and long-term prognosis of women with BrS.

METHODS

A multicenter retrospective study of patients diagnosed with BrS and previous electrophysiological study (EPS) was performed.

RESULTS

Among 770 patients, 177 (23%) were female. At presentation, 150 (84.7%) were asymptomatic. Females presented less frequently with a type 1 electrocardiographic pattern (30.5% vs 55.0%; P <.001), had a higher rate of family history of sudden cardiac death (49.7% vs 29.8%; P <.001), and had less sustained ventricular arrhythmias (VAs) on EPS (8.5% vs 15.1%; P = .009). Genetic testing was performed in 79 females (45% of the sample) and was positive in 34 (19%). An implantable cardioverter-defibrillator was inserted in 48 females (27.1%). During mean (± SD) follow-up of 122.17 ± 57.28 months, 5 females (2.8%) experienced a cardiovascular event compared to 42 males (7.1%; P = .04). On multivariable analysis, a positive genetic test (18.71; 95% confidence interval [CI] 1.82-192.53; P = .01) and atrial fibrillation (odds ratio 21.12; 95% CI 1.27-350.85; P = .03) were predictive of arrhythmic events, whereas VAs on EPS (neither with 1 or 2 extrastimuli nor 3 extrastimuli) were not.

CONCLUSION

Women with BrS represent a minor fraction among patients with BrS, and although their rate of events is low, they do not constitute a risk-free group. Neither clinical risk factors nor EPS predicts future arrhythmic events. Only atrial fibrillation and positive genetic test were identified as risk factors for future arrhythmic events.

Clinical characteristics and long-term clinical course of patients with Brugada syndrome without previous cardiac arrest: a multiparametric risk stratification approach

AIMS

Risk stratification in Brugada syndrome (BrS) still represents an unsettled issue. In this multicentre study, we aimed to evaluate the clinical characteristics and the long-term clinical course of patients with BrS.

METHODS AND RESULTS

A total of 111 consecutive patients (86 males; aged 45.3 ± 13.3 years) diagnosed with BrS were included and followed-up in a prospective fashion. Thirty-seven patients (33.3%) were symptomatic at enrolment (arrhythmic syncope). An electrophysiological study (EPS) was performed in 59 patients (53.2%), and ventricular arrhythmias were induced in 32 (54.2%). A cardioverter defibrillator was implanted in 34 cases (30.6%). During a mean follow-up period of 4.6 ± 3.5 years, appropriate device therapies occurred in seven patients. Event-free survival analysis (log-rank test) showed that spontaneous type-1 electrocardiogram pattern (P = 0.008), symptoms at presentation (syncope) (P = 0.012), family history of sudden cardiac death (P < 0.001), positive EPS (P = 0.024), fragmented QRS (P = 0.004), and QRS duration in lead V2 > 113 ms (P < 0.001) are predictors of future arrhythmic events. Event rates were 0%, 4%, and 60% among patients with 0-1 risk factor, 2-3 risk factors, and 4-5 risk factors, respectively (P < 0.001). Current multiparametric score models exhibit an excellent negative predictive value and perform well in risk stratification of BrS patients.

CONCLUSIONS

Multiparametric models including common risk factors appear to provide better risk stratification of BrS patients than single factors alone.

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.

Comparable clinical characteristics in Brugada syndrome patients harboring SCN5A or novel SCN10A variants

AIMS

The Brugada syndrome (BrS) is an inherited disease associated with an increased risk of sudden cardiac death. Often, the genetic cause remains undetected. Perhaps due at least in part because the NaV1.8 protein is expressed more in both the central and peripheral nervous systems than in the heart, the SCN10A gene is not included in diagnostic arrhythmia/sudden death panels in the vast majority of cardiogenetics centres.

METHODS AND RESULTS

Clinical characteristics were assessed in patients harboring either SCN5A or novel SCN10A variants. Genetic testing was performed using Next Generation Sequencing on genomic DNA. Clinical characteristics, including the arrhythmogenic substrate, in BrS patients harboring novel SCN10A variants and SCN5A variants are comparable. Clinical characteristics, including gender, age, personal history of cardiac arrest/syncope, spontaneous BrS electrocardiogram pattern, family history of sudden death, and arrhythmic substrate are not significantly different between probands harboring SCN10A or SCN5A variants.

CONCLUSION

Future studies are warranted to further characterize the role of these specific SCN10A variants.

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: 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.

Novel SCN5A p.V1429M Variant Segregation in a Family with Brugada Syndrome

Brugada syndrome (BrS) is diagnosed by the presence of an elevated ST-segment and can result in sudden cardiac death. The most commonly found mutated gene is SCN5A, which some argue is the only gene that has been definitively confirmed to cause BrS, while the potential causative effect of other genes is still under debate. While the issue of BrS genetics is currently a hot topic, current knowledge is not able to result in molecular confirmation of over half of BrS cases. Therefore, it is difficult to develop research models with wide potential. Instead, the clinical genetics first need to be better understood. In this study, we provide crucial human data on the novel heterozygous variant NM_198056.2:c.4285G>A (p.Val1429Met) in the SCN5A gene, and demonstrate its segregation with BrS, suggesting a pathogenic effect. These results provide the first disease association with this variant and are crucial clinical data to communicate to basic scientists, who could perform functional studies to better understand the molecular effects of this clinically-relevant variant in BrS.

Inherited cardiac arrhythmias

The main inherited cardiac arrhythmias are long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome. These rare diseases are often the underlying cause of sudden cardiac death in young individuals and result from mutations in several genes encoding ion channels or proteins involved in their regulation. The genetic defects lead to alterations in the ionic currents that determine the morphology and duration of the cardiac action potential, and individuals with these disorders often present with syncope or a life-threatening arrhythmic episode. The diagnosis is based on clinical presentation and history, the characteristics of the electrocardiographic recording at rest and during exercise and genetic analyses. Management relies on pharmacological therapy, mostly β-adrenergic receptor blockers (specifically, propranolol and nadolol) and sodium and transient outward current blockers (such as quinidine), or surgical interventions, including left cardiac sympathetic denervation and implantation of a cardioverter-defibrillator. All these arrhythmias are potentially life-threatening and have substantial negative effects on the quality of life of patients. Future research should focus on the identification of genes associated with the diseases and other risk factors, improved risk stratification and, in particular for Brugada syndrome, effective therapies.

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.

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

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

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.

Wide QRS complex and the risk of major arrhythmic events in Brugada syndrome patients: A systematic review and meta-analysis

BACKGROUND

Brugada syndrome (BrS) is an inherited arrhythmic disease associated with an increased risk of major arrhythmic events (MAE). Previous studies reported that a wide QRS complex may be useful as a predictor of MAE in BrS patients. We aimed to assess the correlation of wide QRS complex with MAE by a systematic review and meta-analysis.

METHODS

We comprehensively searched the databases of MEDLINE and EMBASE from inception to June 2019. Included studies were cohort and case control studies that reported QRS duration and the relationship between wide QRS complex (>120 milliseconds) and MAE (sudden cardiac death, sudden cardiac arrest, ventricular fibrillation, sustained ventricular tachycardia, or appropriate shock). Data from each study were combined using the random-effects model.

RESULTS

Twenty-two studies from 2007 to 2018 were included in this meta-analysis involving 4,814 BrS patients. The mean age was 46.1 ± 12.8 years. The patients were predominately men (77.6%). Wide QRS duration was an independent predictor of MAE (pooled risk ratio 1.55, 95% confidence interval: 1.04-2.30, P = .30, I 2 = 38.4%). QRS duration was wider in BrS who had history of MAE (weight mean difference = 8.12 milliseconds, 95% confidence interval: 5.75-10.51 milliseconds).

CONCLUSIONS

Our study demonstrated that QRS duration is wider in BrS who had history of MAE, and a wide QRS complex is associated with 1.55 times higher risk of MAE in BrS populations. Wide QRS complex can be considered for risk stratification in prediction of MAE in patients with BrS, especially when considering implantable cardioverter-defibrillator placement in asymptomatic patients.

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.

Pathogenesis and management of Brugada syndrome in schizophrenia: A scoping review

CONTEXT

Excess cardiovascular morbidity and an increased prevalence of sudden cardiac death (SCD) contributes to premature mortality in schizophrenia. Brugada syndrome (BrS) is an important but underrecognized cause of SCD. It is more commonly seen in schizophrenia than in general population controls.

METHODS

We conducted a scoping review to describe the pathogenesis of BrS in schizophrenia and to identify the psychotropic medications that increase the risk of unmasking BrS and associated ventricular arrhythmias resulting in SCD.

FINDINGS

Schizophrenia and BrS share similar calcium channel abnormalities, which may result in aberrant myocardial conductivity. It remains uncertain if there is a genetic pre-disposition for BrS in a subset of patients with schizophrenia. However, the unmasking of Brugada ECG patterns with the use of certain antipsychotics and antidepressants increases the risk of precipitating SCD, independent of QT prolongation.

CONCLUSIONS AND FUTURE DIRECTIONS

Specific cardiology assessment and interventions may be required for the congenital or unmasked Brugada ECG pattern in schizophrenia. The current long-term standard of care for BrS is an implantable cardioverter defibrillator (ICD), but post-implantation psychological effects must be considered. Careful use of antipsychotic and other psychotropic medications is necessary to minimize proarrhythmic effects due to impact on cardiac sodium and calcium ion channels. When prescribing such drugs to patients with schizophrenia, clinicians should be mindful of the potentially fatal unmasking of Brugada ECG patterns and how to manage it. We present recommendations for psychiatrists managing this patient population.

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.