Excellent long-term reproducibility of the electrophysiologic efficacy of quinidine in patients with idiopathic ventricular fibrillation and Brugada syndrome

Is ischemic stimulus involved for J wave augmentation during coronary angiography and intracoronary administration of normal saline?

BACKGROUND

J waves may be augmented by coronary angiography (CAG) or intracoronary drug administration but the underlying mechanism is unknown.

PURPOSE

The effect of intracoronary normal saline (NS) on J waves were investigated.

PATIENTS AND METHODS

After the standard CAG using iopamidol (IopamiroR Inj), NS was injected into the right coronary artery in 10 patients with and eight patients without J waves at the baseline. The 12-lead ECG was monitored, stored on a computer and retrieved later for measurement of the J wave amplitude before or during the coronary interventions.

RESULTS

J waves in leads II, III and aVF at baseline increased significantly in each lead during the right CAG and NS injection into the right coronary artery. The J wave changes were similar between the two interventions and distinct similar alterations were observed in the QRS complex. We postulated that the ischemic myocardium that was induced during CAG or intracoronary NS administration slowed the conduction velocity of depolarization in the perfusion territory and delayed the timing of J waves to appear. Then, the delayed appearance of J waves would be less opposed by electromotive force from other areas resulting in augmentation.

CONCLUSION

J wave augmentation was observed during CAG and intracoronary NS administration. As a mechanism of augmentation, we postulated that contrast media and NS induce myocardial ischemia and delay the timing of J waves to a point of less opposition by electromotive force from other areas.

HIGHLIGHTS

J wave augmentation has been reported during intracoronary injection of contrast media or drugs. The present study confirmed that normal saline alone was able to augment J waves. Mechanistically, coronary interventions using anoxic solutions can cause regional myocardial ischemia and reduce the conduction velocity of depolarization. Then, delayed J waves are less opposed by the electromotive force from remote areas which leads to augmentation. When a drug is diluted in normal saline and given intracoronarily, changes in J waves can be due to normal saline. The pathophysiological and clinical significance of J waves augmented during coronary interventions need to be established.

Quinidine for ventricular arrhythmias: A comprehensive review

Quinidine, the first antiarrhythmic drug, was widely used during the 20th century. Multiple studies have been conducted to provide insights into the pharmacokinetics and pleiotropic effects of Class Ia antiarrhythmic drugs. However, safety concerns and the emergence of new drugs led to a decline in their use during the 1990s. Despite this, recent studies have reignited the interest in quinidine, particularly for ventricular arrhythmias, where other antiarrhythmics have failed. In conditions such as Brugada syndrome, idiopathic ventricular fibrillation, early repolarization syndrome, short QT syndrome, and electrical storms, quinidine remains a valuable asset. Starting from the European and American recommendations, this comprehensive review aimed to explore the various indications for quinidine and the studies that support its use. We also discuss the potential future of quinidine, including the necessary research to optimize its use and patient selection. Additionally, it addresses the imperative task of mitigating the iatrogenic burden associated with quinidine usage and confronts the challenge of ensuring drug accessibility.

Management of patients with an electrical storm or clustered ventricular arrhythmias: a clinical consensus statement of the European Heart Rhythm Association of the ESC-endorsed by the Asia-Pacific Heart Rhythm Society, Heart Rhythm Society, and Latin-American Heart Rhythm Society

Electrical storm (ES) is a state of electrical instability, manifesting as recurrent ventricular arrhythmias (VAs) over a short period of time (three or more episodes of sustained VA within 24 h, separated by at least 5 min, requiring termination by an intervention). The clinical presentation can vary, but ES is usually a cardiac emergency. Electrical storm mainly affects patients with structural or primary electrical heart disease, often with an implantable cardioverter-defibrillator (ICD). Management of ES requires a multi-faceted approach and the involvement of multi-disciplinary teams, but despite advanced treatment and often invasive procedures, it is associated with high morbidity and mortality. With an ageing population, longer survival of heart failure patients, and an increasing number of patients with ICD, the incidence of ES is expected to increase. This European Heart Rhythm Association clinical consensus statement focuses on pathophysiology, clinical presentation, diagnostic evaluation, and acute and long-term management of patients presenting with ES or clustered VA.

Short-Coupled Ventricular Fibrillation

Short-coupled ventricular fibrillation (SCVF) is a distinct phenotype among individuals with unexplained cardiac arrest accounting for 7% to 14% of cases of idiopathic ventricular fibrillation (IVF). VF is typically initiated by a trigger premature ventricular contraction with a short-coupling interval of less than 350 milliseconds. In the absence of specific electrocardiographic features or provocative tests, the diagnosis remains challenging and requires documentation of VF onset. Most cases are diagnosed during follow-up at the time of VF recurrence. SCVF is characterized by a high risk of VF recurrence. Insertion of an implantable cardioverter-defibrillator and quinidine are the keystones of SCVF management.

J wave dynamicity during coronary angiography and intracoronary acetylcholine administration

BACKGROUND

J-waves may be observed during coronary angiography (CAG) or intracoronary acetylcholine (ACh) administration, but their significance is unknown.

METHODS

Forty-nine patients, 59.1 ± 11.5 years old and 59% male, were studied on suspicion of vasospastic angina, and J wave dynamicity was compared between CAG and Ach administration.

RESULTS

Diagnostic (≥0.1 mV) or nondiagnostic (<0.1 mV) J waves in 9 and 3 patients, respectively, were augmented, and J waves were newly observed in 2 patients during CAG and Ach administration. Similar changes in the J-wave amplitude were observed: from 0.10 ± 0.09 mV to 0.20 ± 0.15 mV (p < .002) and from 0.10 ± 0.10 mV to 0.20 ± 0.16 mV (p < .001) during CAG and Ach administration, respectively. J waves were located in the inferior leads and changed only during the right coronary interventions. In the remaining 35 patients, J waves were absent before and during the coronary interventions. Augmentation of J waves was found when the RR interval was shortened in some patients. Injection of anoxic media into the coronary artery might induce a conduction delay from myocardial ischemia that manifests as augmentation or new occurrence of J waves.

CONCLUSIONS

Both CAG and intracoronary Ach administration affected J waves similarly in the same individuals. A myocardial ischemia-induced conduction delay may be responsible for the changes in J waves, but further studies are needed.

Trigger and Substrate Mapping and Ablation for Ventricular Fibrillation in the Structurally Normal Heart

Sudden cardiac death (SCD) represents approximately 50% of all cardiovascular mortality in the United States. The majority of SCD occurs in individuals with structural heart disease; however, around 5% of individuals have no identifiable cause on autopsy. This proportion is even higher in those <40 years old, where SCD is particularly devastating. Ventricular fibrillation (VF) is often the terminal rhythm leading to SCD. Catheter ablation for VF has emerged as an effective tool to alter the natural history of this disease among high-risk individuals. Important advances have been made in the identification of several mechanisms involved in the initiation and maintenance of VF. Targeting the triggers of VF as well as the underlying substrate that perpetuates these lethal arrhythmias has the potential to eliminate further episodes. Although important gaps remain in our understanding of VF, catheter ablation has become an important option for individuals with refractory arrhythmias. This review outlines a contemporary approach to the mapping and ablation of VF in the structurally normal heart, specifically focusing on the following major conditions: idiopathic ventricular fibrillation, short-coupled ventricular fibrillation, and the J-wave syndromes-Brugada syndrome and early-repolarization syndrome.

The Brugada syndrome: pharmacological therapy

Brugada syndrome is an inherited channelopathy with an increased risk of sudden cardiac death (SCD) due to ventricular arrhythmias (VA) and an increased incidence of supraventricular arrhythmias, as compared with the general population. For the prevention of SCD, the guidelines recommend the implantable cardioverter-defibrillator (ICD); however, ICD does not prevent VA. In this article, we provide a brief review of the literature on the Brugada syndrome pharmacological therapy, mainly focusing on quinidine treatment. The efficacy of quinidine therapy in the prevention of VA in Brugada syndrome has been demonstrated by several small studies in patients with ICD and recurrent shocks or in asymptomatic patients with inducible ventricular fibrillation (VF) at electrophysiological study. Quinidine has also been tested for the prophylaxis of supraventricular arrhythmias, especially atrial fibrillation/flutter, and in paediatric patients. In these studies, quinidine proved highly effective in preventing re-induction of VF and spontaneous recurrences of both ventricular and supraventricular arrhythmias. Unfortunately, this therapy is burdened by a high incidence of side effects, which may lead to drug discontinuation.

Exercise in the Genetic Arrhythmia Syndromes - A Review

Provide a brief summary of your article (100-150 words; no references or figures/tables). The synopsis appears only in the table of contents and is often used by indexing services such as PubMed. Genetic arrhythmia syndromes are rare, yet harbor the potential for highly consequential, often unpredictable arrhythmias or sudden death events. There has been historical uncertainty regarding the correct advice to offer to affected patients who are reasonably wanting to participate in sporting and athletic endeavors. In some cases, this had led to abundantly cautious disqualifications, depriving individuals from participation unnecessarily. Societal guidance and expert opinion has evolved significantly over the last decade or 2, along with our understanding of the genetics and natural history of these conditions, and the emphasis has switched toward shared decision making with respect to the decision to participate or not, with patients and families becoming better informed, and willing participants in the decision making process. This review aims to give a brief update of the salient issues for the busy physician concerning these syndromes and to provide a framework for approaching their management in the otherwise aspirational or keen sports participant.

Short-Coupled Idiopathic Ventricular Fibrillation: A Literature Review With Extended Follow-Up

Idiopathic ventricular fibrillation is responsible for approximately 10% of cases of aborted cardiac arrest. Recent studies have shown that short-coupled ventricular premature complexes are present at the onset of idiopathic ventricular fibrillation in 6.6%-17% of patients. The present review provided information on 86 patients with short-coupled malignant ventricular arrhythmias that were reported as case reports or small patient series during the last 70 years. In 75% of the 81 cases published during the last 40 years, extended information and follow-up (from 2.63 ± 4.5 to 10.67 ± 7.8 years; P < 0.001, between the original publication to the latest update) could be obtained from the authors. The review shows that short-coupled malignant ventricular arrhythmias occurred almost equally in males and females, at the mean age of 40 years. A tendency for later occurrence of the arrhythmia by 4 years was observed in females. A prior history of syncope was noted in 45.3% of the patients, whereas arrhythmic storm occurred in 42% at presentation. The most common mode of revelation of short-coupled malignant ventricular arrhythmias was syncope (53.5%), followed by aborted cardiac arrest (26.7%) and recurrent arrhythmic event after prior implantable-cardioverter defibrillator implantation for idiopathic ventricular fibrillation (17.4%). For the first time, short-coupled malignant arrhythmias exhibiting "not-so-short" coupling intervals (≥350 ms) were found in a significant proportion of patients (17.4%). During long-term follow-up, quinidine yielded a slightly higher success rate in arrhythmia control than ablation. Larger studies are necessary to assess the best strategy for the management of this potentially lethal arrhythmia.

Short-coupled ventricular fibrillation represents a distinct phenotype among latent causes of unexplained cardiac arrest: a report from the CASPER registry

AIMS

The term idiopathic ventricular fibrillation (IVF) describes survivors of unexplained cardiac arrest (UCA) without a specific diagnosis after clinical and genetic testing. Previous reports have described a subset of IVF individuals with ventricular arrhythmia initiated by short-coupled trigger premature ventricular contractions (PVCs) for which the term short-coupled ventricular fibrillation (SCVF) has been proposed. The aim of this article is to establish the phenotype and frequency of SCVF in a large cohort of UCA survivors.

METHODS AND RESULTS

We performed a multicentre study including consecutive UCA survivors from the CASPER registry. Short-coupled ventricular fibrillation was defined as otherwise unexplained ventricular fibrillation initiated by a trigger PVC with a coupling interval of <350 ms. Among 364 UCA survivors, 24/364 (6.6%) met diagnostic criteria for SCVF. The diagnosis of SCVF was obtained in 19/24 (79%) individuals by documented ventricular fibrillation during follow-up. Ventricular arrhythmia was initiated by a mean PVC coupling interval of 274 ± 32 ms. Electrical storm occurred in 21% of SCVF probands but not in any UCA proband (P < 0.001). The median time to recurrent ventricular arrhythmia in SCVF was 31 months. Recurrent ventricular fibrillation resulted in quinidine administration in 12/24 SCVF (50%) with excellent arrhythmia control.

CONCLUSION

Short-coupled ventricular fibrillation is a distinct primary arrhythmia syndrome accounting for at least 6.6% of UCA. As documentation of ventricular fibrillation onset is necessary for the diagnosis, most cases are diagnosed at the time of recurrent arrhythmia, thus the true prevalence of SCVF remains still unknown. Quinidine is effective in SCVF and should be considered as first-line treatment for patients with recurrent episodes.

Remote Monitoring of the QT Interval and Emerging Indications for Arrhythmia Prevention

QT interval prolongation is a marker of increased risk for life-threatening arrhythmias, and needs to be promptly recognized. Many effective drugs, however, prolong QTc (QT interval corrected for heart rate) in genetically predisposed subjects. The possibility of remote monitoring and QTc measurement for up to 2 weeks, continuously providing physicians with real time data, allows life-saving interventions or changes in drug therapy. This applies especially to patients with the long QT syndrome and to those taking drugs blocking the IKr current and prolonging the QT interval. Patch monitors recording ECG traces continuously are available and contribute to effective arrhythmic prevention.

Quinidine in the Management of Recurrent Ventricular Arrhythmias: A Reappraisal

OBJECTIVE

This study aimed to review the utility of quinidine in patients presenting with recurrent sustained ventricular arrhythmia (VA) and limited antiarrhythmic drug (AAD) options.

BACKGROUND

Therapeutic options are often limited in patients with structural heart disease and recurrent VAs. Quinidine has an established role in rare arrhythmic syndromes, but its potential use in other difficult VAs has not been assessed in the present era.

METHODS

We performed a retrospective analysis of 37 patients who had in-hospital quinidine initiation after multiple other therapies failed for VA suppression at our tertiary referral center. Clinical data and outcomes were obtained from the medical record.

RESULTS

Of 30 patients with in-hospital quantifiable VA episodes, quinidine reduced acute VA from a median of 3 episodes (interquartile range [IQR]: 2 to 7.5) to 0 (IQR: 0 to 0.5) during medians of 3 days before and 4 days after quinidine initiation (p < 0.001). VA events decreased from a median of 10.5 episodes per day (IQR: 5 to 15) to 0.5 episodes (IQR: 0 to 4) after quinidine initiation in the 12 patients presenting with electrical storm (p = 0.004). Among the 24 patients discharged on quinidine, 13 (54.2%) had VA recurrence during a median of 138 days. Adverse effects in 9 of the 37 patients (24.3%) led to drug discontinuation, most commonly gastrointestinal intolerance.

CONCLUSIONS

In patients with recurrent VAs and structural heart disease who have limited treatment options, quinidine can be useful, particularly as a short-term therapy.

J waves induced during coronary angiography in patients with vasospastic angina and its implication

BACKGROUND

J waves may develop during coronary angiography (CAG).

PATIENTS AND RESULTS

Seven patients (61±6 years, 6 male) had vasospastic angina. ST-segment elevation and ventricular fibrillation were documented in all patients. CAG revealed normal arteries, but slurring or notching (J waves) with an amplitude of 0.20±0.06 mV appeared for the first time (n=6) or in an augmented manner (n=1) with distinct alterations in QRS morphology when contrast medium was injected into the right coronary artery.

CONCLUSION

In patients with vasospastic angina, J waves observed during CAG can be a manifestation of a local conduction delay caused by contrast medium-induced myocardial ischemia.

Torsades De Pointes Electrical Storm Induced by H1N1 in a Patient with KCNH2 Variant of Unknown Significance

This report describes a case of an electrical storm of Torsades De Pointes in a structurally normal heart, following an H1N1 infection in the presence of a genetic variant of unknown significance. The patient was successfully treated with isoproterenol. This case highlights the dilemma of evaluating novel genetic testing results in a clinical setting.

Out-of-hospital cardiac arrest due to idiopathic ventricular fibrillation in patients with normal electrocardiograms: results from a multicentre long-term registry

AIMS

To define the clinical characteristics and long-term clinical outcomes of a large cohort of patients with idiopathic ventricular fibrillation (IVF) and normal 12-lead electrocardiograms (ECGs).

METHODS AND RESULTS

Patients with ventricular fibrillation as the presenting rhythm, normal baseline, and follow-up ECGs with no signs of cardiac channelopathy including early repolarization or atrioventricular conduction abnormalities, and without structural heart disease were included in a registry. A total of 245 patients (median age: 38 years; males 59%) were recruited from 25 centres. An implantable cardioverter-defibrillator (ICD) was implanted in 226 patients (92%), while 18 patients (8%) were treated with drug therapy only. Over a median follow-up of 63 months (interquartile range: 25-110 months), 12 patients died (5%); in four of them (1.6%) the lethal event was of cardiac origin. Patients treated with antiarrhythmic drugs only had a higher rate of cardiovascular death compared to patients who received an ICD (16% vs. 0.4%, P = 0.001). Fifty-two patients (21%) experienced an arrhythmic recurrence. Age ≤16 years at the time of the first ventricular arrhythmia was the only predictor of arrhythmic recurrence on multivariable analysis [hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.18-0.92; P = 0.03].

CONCLUSION

Patients with IVF and persistently normal ECGs frequently have arrhythmic recurrences, but a good prognosis when treated with an ICD. Children are a category of IVF patients at higher risk of arrhythmic recurrences.

J wave syndromes as a cause of malignant cardiac arrhythmias

The J wave syndromes, including the Brugada (BrS) and early repolarization (ERS) syndromes, are characterized by the manifestation of prominent J waves in the electrocardiogram appearing as an ST segment elevation and the development of life-threatening cardiac arrhythmias. BrS and ERS differ with respect to the magnitude and lead location of abnormal J waves and are thought to represent a continuous spectrum of phenotypic expression termed J wave syndromes. Despite over 25 years of intensive research, risk stratification and the approach to therapy of these two inherited cardiac arrhythmia syndromes are still rapidly evolving. Our objective in this review is to provide an integrated synopsis of the clinical characteristics, risk stratifiers, as well as the molecular, ionic, cellular, and genetic mechanisms underlying these two syndromes that have captured the interest and attention of the cardiology community over the past two decades.

Recent advances in the treatment of Brugada syndrome

INTRODUCTION

Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by ST-segment elevation in right precordial ECG leads and associated with sudden cardiac death in young adults. The ECG manifestations of BrS are often concealed but can be unmasked by sodium channel blockers and fever. Areas covered: Implantation of a cardioverter defibrillator (ICD) is first-line therapy for BrS patients presenting with prior cardiac arrest or documented VT. A pharmacological approach to therapy is recommended in cases of electrical storm, as an adjunct to ICD and as preventative therapy. The goal of pharmacological therapy is to produce an inward shift to counter the genetically-induced outward shift of ion channel current flowing during the early phases of the ventricular epicardial action potential. This is accomplished by augmentation of I_Ca using □□adrenergic agents or phosphodiesterase III inhibitors or via inhibition of I_to. Radiofrequency ablation of the right ventricular outward flow tract epicardium is effective in suppressing arrhythmogenesis in BrS patients experiencing frequent appropriate ICD-shocks. Expert commentary: Understanding of the pathophysiology and approach to therapy of BrS has advanced considerably in recent years, but there remains an urgent need for development of cardio-selective and ion-channel-specific I_to blockers for treatment of BrS.

Controversies in Brugada syndrome

The Brugada syndrome is an inherited channelopathy associated with increased risk of ventricular arrhythmias and sudden death, often occurring during sleep or resting conditions. Although this entity has been described more than 20 years ago, it remains one of the most debated among channelopathies, with several open questions on its genetic substrate, arrhythmia mechanisms, and clinical management. Studies on the genetics and physiopathology bases of the Brugada syndrome have opened novel investigative pathways and concepts that are now entering the field of cardiovascular genetics and are applied to other inherited arrhythmias. In this perspective, Brugada syndrome can be seen as an example on how basic science discoveries have influenced clinical management and led to novel therapeutic approaches.

Low-Dose Quinidine Effectively Reduced Shocks in Brugada Syndrome Patients with an Implantable Cardioverter Defibrillator: A Chinese Case Series Report

BACKGROUND

Only implantable cardioverter defibrillators (ICD) have been proven to prevent sudden cardiac death (SCD) in patients with Brugada syndrome (BrS). However, ICD discharge, whether appropriate or inappropriate, leads to impaired quality of life and even increases rehospitalization. Quinidine might prevent the recurrence of ventricular arrhythmia (VA); however, the effect of low-dose quinidine for preventing spontaneous arrhythmias remains less clear.

METHODS

In our cardiology center, 10 confirmed patients with BrS (all men, mean age 38.7 ± 6.72 years) who underwent appropriate ICD shocks due to recurrent VAs were treated with quinidine (≤200 mg/day) and followed regularly.

RESULTS

All the patients underwent ICD shocks due to ventricular tachycardia (VT)/ventricular fibrillation (VF) before taking quinidine. A 24-hour distribution of VT/VF demonstrated that most of the events occurred in the sleeping time from 22:00 to 8:00. Quinidine prevented recurrence of VAs in nine patients. The other one patient took quinidine discontinuously because of anxiety suffered from less episodes of VA, and after psychological guidance, he took quinidine 200 mg/day and experienced no VA episodes from then on. In our series, only one patient suffered leukopenia related to quinidine. No other side effect was observed.

CONCLUSIONS

Quinidine with a very low dose (≤200 mg/day) well controlled VT/VF recurrence for a long-term period in Chinese patients with BrS. Administration (at 21:00) according to the circadian distribution of VT/VF episodes might increase the efficiency and improve the patient's tolerance.

J Wave Syndromes: History and Current Controversies

The concept of J wave syndromes was first proposed in 2004 by Yan et al for a spectrum of electrocardiographic (ECG) manifestations of prominent J waves that are associated with a potential to predispose affected individuals to ventricular fibrillation (VF). Although the concept of J wave syndromes is widely used and accepted, there has been tremendous debate over the definition of J wave, its ionic and cellular basis and arrhythmogenic mechanism. In this review article, we attempted to discuss the history from which the concept of J wave syndromes (JWS) is evolved and current controversies in JWS.

Early Repolarization Syndrome; Mechanistic Theories and Clinical Correlates

The early repolarization (ER) pattern on the 12-lead electrocardiogram is characterized by J point elevation in the inferior and/or lateral leads. The ER pattern is associated with an increased risk of ventricular arrhythmias and sudden cardiac death (SCD). Based on studies in animal models and genetic studies, it has been proposed that J point elevation in ER is a manifestation of augmented dispersion of repolarization which creates a substrate for ventricular arrhythmia. A competing theory regarding early repolarization syndrome (ERS) proposes that the syndrome arises as a consequence of abnormal depolarization. In recent years, multiple clinical studies have described the characteristics of ER patients with VF in more detail. The majority of these studies have provided evidence to support basic science observations. However, not all clinical observations correlate with basic science findings. This review will provide an overview of basic science and genetic research in ER and correlate basic science evidence with the clinical phenotype.

Outcome of Apparently Unexplained Cardiac Arrest: Results From Investigation and Follow-Up of the Prospective Cardiac Arrest Survivors With Preserved Ejection Fraction Registry

BACKGROUND

The Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) enrolls patients with apparently unexplained cardiac arrest and no evident cardiac disease to identify the pathogenesis of cardiac arrest through systematic clinical testing. Exercise testing, drug provocation, advanced cardiac imaging, and genetic testing may be useful when a cause is not apparent.

METHODS AND RESULTS

The first 200 survivors of unexplained cardiac arrest from 14 centers across Canada were evaluated to determine the results of investigation and follow-up (age, 48.6±14.7 years, 41% female). Patients were free of evidence of coronary artery disease, left ventricular dysfunction, or evident repolarization syndromes. Advanced testing determined a diagnosis in 34% of patients at baseline, with a diagnosis emerging during follow-up in 7% of patients. Of those who were diagnosed, 28 (35%) had an underlying structural condition and 53 (65%) had a primary electric disease. During a mean follow-up of 3.15±2.34 years, 23% of patients had either a shock or an appropriate antitachycardia pacing from their implantable cardioverter defibrillator, or both. The implantable cardioverter defibrillator appropriate intervention rate was 8.4% at 1 year and 18.1% at 3 years, with no clear difference between diagnosed and undiagnosed subjects, or between those diagnosed with a primary electric versus structural pathogenesis.

CONCLUSIONS

Obtaining a diagnosis in previously unexplained cardiac arrest patients requires systematic clinical testing and regular follow-up to unmask the cause. Nearly half of apparently unexplained cardiac arrest patients ultimately received a diagnosis, allowing for improved treatment and family screening. A substantial proportion of patients received appropriate implantable cardioverter defibrillator therapy during medium-term follow-up.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00292032.

Impact of clinical and genetic findings on the management of young patients with Brugada syndrome

BACKGROUND

Brugada syndrome (BrS) is an arrhythmogenic disease associated with sudden cardiac death (SCD) that seldom manifests or is recognized in childhood.

OBJECTIVES

The objectives of this study were to describe the clinical presentation of pediatric BrS to identify prognostic factors for risk stratification and to propose a data-based approach management.

METHODS

We studied 106 patients younger than 19 years at diagnosis of BrS enrolled from 16 European hospitals.

RESULTS

At diagnosis, BrS was spontaneous (n = 36, 34%) or drug-induced (n = 70, 66%). The mean age was 11.1 ± 5.7 years, and most patients were asymptomatic (family screening, (n = 67, 63%; incidental, n = 13, 12%), while 15 (14%) experienced syncope, 6(6%) aborted SCD or symptomatic ventricular tachycardia, and 5 (5%) other symptoms. During follow-up (median 54 months), 10 (9%) patients had life-threatening arrhythmias (LTA), including 3 (3%) deaths. Six (6%) experienced syncope and 4 (4%) supraventricular tachycardia. Fever triggered 27% of LTA events. An implantable cardioverter-defibrillator was implanted in 22 (21%), with major adverse events in 41%. Of the 11 (10%) patients treated with hydroquinidine, 8 remained asymptomatic. Genetic testing was performed in 75 (71%) patients, and SCN5A rare variants were identified in 58 (55%); 15 of 32 tested probands (47%) were genotype positive. Nine of 10 patients with LTA underwent genetic testing, and all were genotype positive, whereas the 17 SCN5A-negative patients remained asymptomatic. Spontaneous Brugada type 1 electrocardiographic (ECG) pattern (P = .005) and symptoms at diagnosis (P = .001) were predictors of LTA. Time to the first LTA event was shorter in patients with both symptoms at diagnosis and spontaneous Brugada type 1 ECG pattern (P = .006).

CONCLUSION

Spontaneous Brugada type 1 ECG pattern and symptoms at diagnosis are predictors of LTA events in the young affected by BrS. The management of BrS should become age-specific, and prevention of SCD may involve genetic testing and aggressive use of antipyretics and quinidine, with risk-specific consideration for the implantable cardioverter-defibrillator.

Brugada Syndrome: Clinical, Genetic, Molecular, Cellular, and Ionic Aspects

Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome first described as a new clinical entity in 1992. Electrocardiographically characterized by distinct coved type ST segment elevation in the right-precordial leads, the syndrome is associated with a high risk for sudden cardiac death in young adults, and less frequently in infants and children. The electrocardiographic manifestations of BrS are often concealed and may be unmasked or aggravated by sodium channel blockers, a febrile state, vagotonic agents, as well as by tricyclic and tetracyclic antidepressants. An implantable cardioverter defibrillator is the most widely accepted approach to therapy. Pharmacologic therapy is designed to produce an inward shift in the balance of currents active during the early phases of the right ventricular action potential (AP) and can be used to abort electrical storms or as an adjunct or alternative to device therapy when use of an implantable cardioverter defibrillator is not possible. Isoproterenol, cilostazol, and milrinone boost calcium channel current and drugs like quinidine, bepridil, and the Chinese herb extract Wenxin Keli inhibit the transient outward current, acting to diminish the AP notch and thus to suppress the substrate and trigger for ventricular tachycardia or fibrillation. Radiofrequency ablation of the right ventricular outflow tract epicardium of patients with BrS has recently been shown to reduce arrhythmia vulnerability and the electrocardiographic manifestation of the disease, presumably by destroying the cells with more prominent AP notch. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of BrS as well as the approach to therapy.

Role of pharmacotherapy in cardiac ion channelopathies

In the last decade, there have been considerable advances in the understanding of the pathophysiology of malignant ventricular tachyarrhythmias (VT) and sudden cardiac death (SCD). Over 80% of SCD occurs in patients with organic heart disease. However, approximately 10%-15% of SCD occurs in the presence of structurally normal heart, and the majority of these patients are young. In this group of patients, changes in genes encoding cardiac ion channels produce modifications of the function of the channel resulting in an electrophysiological substrate of VT and SCD. Collectively, these disorders are referred to as cardiac ion channelopathies. The four major syndromes in this group are: the long QT syndrome (LQTS), the Brugada syndrome (BrS), the short QT syndrome (SQTS), and the catecholaminergic polymorphic ventricular tachycardia (CPVT). Each of these syndromes includes multiple subtypes with different and sometimes complex cardiac ion channel genetic abnormalities. Many are associated with other somatic and neurological abnormalities besides the risk of VT and SCD. The current management of cardiac ion channelopathies can be summarized as follows: (1) in symptomatic patients, the implantable cardioverter defibrillator (ICD) is the only viable option; (2) in asymptomatic patients, risk stratification is necessary, followed by either the ICD, pharmacotherapy, or a combination of both. A genotype-specific approach to pharmacotherapy requires a thorough understanding of the molecular-cellular basis of arrhythmogenesis in cardiac ion channelopathies as well as the specific drug profile.

Management of Brugada Syndrome: Thirty-Three-Year Experience Using Electrophysiologically Guided Therapy With Class 1A Antiarrhythmic Drugs

BACKGROUND

Information on long-term clinical outcome of patients with Brugada syndrome treated with electrophysiologically guided class 1A antiarrhythmic drugs (AAD) is limited.

METHODS AND RESULTS

An aggressive protocol of programmed ventricular stimulation was performed in 96 patients with Brugada syndrome (88% males; mean age, 39.8±15.9 years). Ten patients were cardiac arrest survivors, 27 had presented with syncope, and 59 were asymptomatic. Ventricular fibrillation was induced in 66 patients, including 100%, 74%, and 61% of patients with cardiac arrest, syncope, and no symptoms, respectively. All but 6 of the 66 patients with inducible ventricular fibrillation underwent electrophysiological testing on quinidine (n=54), disopyramide (n=2), or both (n=4). Fifty-four (90%) patients were electrophysiological responders to >1 AAD with similar efficacy rates (≈90%) in all patients groups. Patients with no inducible ventricular fibrillation at baseline were left on no therapy. After a mean follow-up of 113.3±71.5 months, 92 patients were alive, whereas 4 died from noncardiac causes. No arrhythmic event occurred during class 1A AAD therapy in any of electrophysiological drug responders and in patients with no baseline inducible ventricular fibrillation. Arrhythmic events occurred in only 2 cardiac arrest survivors treated with implantable cardioverter-defibrillator alone but did not recur on quinidine. All cases of recurrent syncope (n=12) were attributed to a vasovagal (n=10) or nonarrhythmic mechanism (n=2). Class 1A AAD therapy resulted in 38% incidence of side effects that resolved after drug discontinuation.

CONCLUSIONS

Our data suggest that electrophysiologically guided class 1A AAD treatment has a place in our therapeutic armamentarium for all types of patients with Brugada syndrome.

J-wave syndromes: Brugada and early repolarization syndromes

A prominent J wave is encountered in a number of life-threatening cardiac arrhythmia syndromes, including the Brugada syndrome and early repolarization syndromes. Brugada syndrome and early repolarization syndromes differ with respect to the magnitude and lead location of abnormal J waves and are thought to represent a continuous spectrum of phenotypic expression termed J-wave syndromes. Despite two decades of intensive research, risk stratification and the approach to therapy of these 2 inherited cardiac arrhythmia syndromes are still undergoing rapid evolution. Our objective in this review is to provide an integrated synopsis of the clinical characteristics, risk stratifiers, and molecular, ionic, cellular, and genetic mechanisms underlying these 2 fascinating syndromes that have captured the interest and attention of the cardiology community in recent years.

Novel Therapeutic Strategies for the Management of Ventricular Arrhythmias Associated with the Brugada Syndrome

INTRODUCTION

Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by prominent J waves appearing as distinct coved type ST segment elevation in the right precordial leads of the ECG. It is associated with a high risk for sudden cardiac death.

AREAS COVERED

We discuss 1) ECG manifestations of BrS which can be unmasked or aggravated by sodium channel blockers, febrile states, vagotonic agents, as well as tricyclic and tetracyclic antidepressants; 2) Genetic basis of BrS; 3) Ionic and cellular mechanisms underlying BrS; 4) Therapy involving devices including an implantable cardioverter defibrillator (ICD); 5) Therapy involving radiofrequency ablation; and 6) Therapy involving pharmacological therapy which is aimed at producing an inward shift in the balance of the currents active during phase 1 of the right ventricular action potential either by boosting calcium channel current (isoproterenol, cilostazol and milrinone) or by inhibition of transient outward current Ito (quinidine, bepridil and the Chinese herb extract Wenxin Keli).

EXPERT OPINION

This review provides an overview of the clinical and molecular aspects of BrS with a focus on approaches to therapy. Available data suggest that agents capable of inhibiting the transient outward current Ito can exert an ameliorative effect regardless of the underlying cause.

Prognostic value of programmed electrical stimulation in Brugada syndrome: 20 years experience

BACKGROUND

The prognostic value of electrophysiological investigations in individuals with Brugada syndrome remains controversial. Different groups have published contradictory data. Long-term follow-up is needed to clarify this issue.

METHODS AND RESULTS

Patients presenting with spontaneous or drug-induced Brugada type I ECG and in whom programmed electric stimulation was performed at our institution were considered eligible for this study. A total of 403 consecutive patients (235 males, 58.2%; mean age, 43.2±16.2 years) were included. Ventricular arrhythmias during programmed electric stimulation were induced in 73 (18.1%) patients. After a mean follow-up time of 74.3±57.3 months (median 57.3), 25 arrhythmic events occurred (16 in the inducible group and 9 in the noninducible). Ventricular arrhythmias inducibility presented a hazard ratio for events of 8.3 (95% confidence interval, 3.6-19.4), P<0.01.

CONCLUSIONS

Programmed ventricular stimulation of the heart is a good predictor of outcome in individuals with Brugada syndrome. It might be of special value to guide further management when performed in asymptomatic individuals. The overall accuracy of the test makes it a suitable screening tool to reassure noninducible asymptomatic individuals.

The usual suspects in sudden cardiac death of the young: a focus on inherited arrhythmogenic diseases

Up to 14,500 young individuals die suddenly every year in Europe of cardiac pathologies. The majority of these tragic events are related to a group of genetic defects that predispose the development of malignant arrhythmias (inherited arrhythmogenic diseases [IADs]). IADs include both cardiomyopathies (hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy) and channelopathies (long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia). Every time an IAD is identified in a patient, other individuals in his/her family may be at risk of cardiac events. However; if a timely diagnosis is made, simple preventative measures may be applied. Genetic studies play a pivotal role in the diagnosis of IADs and may help in the management of patients and their relatives.

Atrial fibrillation in a large population with Brugada electrocardiographic pattern: prevalence, management, and correlation with prognosis

BACKGROUND

A high prevalence of atrial fibrillation/atrial flutter (AF/AFl) has been reported in small series of Brugada patients, with discordant data.

OBJECTIVE

The purpose of this study was to analyze, in a large population of Brugada patients, the prevalence of AF/AFl, its correlation with prognosis, and the efficacy of hydroquinidine (HQ) treatment.

METHODS

Among 560 patients with Brugada type 1 ECG (BrECG), 48 (9%) had AF/AFl. Three groups were considered: 23 patients with BrECG pattern recognized before AF/AFl (group 1); 25 patients first diagnosed with AF/AFl in whom Class IC antiarrhythmic drugs administered for cardioversion/prophylaxis unmasked BrECG (group 2); and 512 patients without AF/AFl (group 3). Recurrence of AF/AFl and occurrence of ventricular arrhythmias were evaluated at follow-up.

RESULTS

Mean age was 47 ± 15 years, 59 ± 11 years, and 44 ± 14 years in groups 1, 2, and 3, respectively. Seven subjects (32%) in group 1 had syncope/aborted sudden death, 1 (4%) in group 2, and 122 (24%) in group 3. Ventricular arrhythmia occurred in three patients in group 1, none in group 2, and 10 in group 3 at median follow-up of 51, 68, and 41 months, respectively. Nine patients in group 1 and nine in group 2 received HQ for AF/AFl prophylaxis; on therapy, none had AF/AFl recurrence.

CONCLUSION

Prevalence of AF/AFl in Brugada patients is higher than in the general population of the same age. Patients in group 1 are younger than those in group 2 and have a worse prognosis compared to both groups 2 and 3. HQ therapy has proved useful and safe in patients with AF/AFl and BrECG.