Efficacy of low-dose bepridil for prevention of ventricular fibrillation in patients with Brugada syndrome with and without SCN5A mutation

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.

Refractoriness to subcutaneous implantable cardioverter defibrillator after frequent therapies for ventricular fibrillation storms in a Brugada syndrome case

Background

The subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to the transvenous implantable cardioverter defibrillator for the prevention of sudden cardiac death. Here, we report a rare case of refractoriness to an S-ICD after frequent therapies for ventricular fibrillation (VF) storms.

Case presentation

A 24-year-old man underwent a bout of syncope with vomiting and incontinence at home. He was brought to the emergency room and was witnessed to spontaneously go into VF successfully converted by external defibrillation. Previously, he was diagnosed with a type I Brugada electrocardiogram pattern by a pilsicainide administration test in another hospital. Although he had a family history of sudden cardiac death in 3 relatives, including his brother, he was followed closely without any therapies because he had never had an episode of syncope. He was implanted with an S-ICD without any trouble. Seven months later, frequent S-ICD shocks for VF storms occurred. His VF was controlled by using intravenous amiodarone, which was converted to an oral preparation. However, his VF recurred after another 2 months. The analysis of his S-ICD data revealed that 4 consecutive shock deliveries could not terminate his VF and the final shock delivered could fortunately terminate it because of a high defibrillation threshold test (DFT) due to an increasing shock impedance (64 to 90 Ω). First, we performed an epicardial Brugada syndrome ablation and subsequently replaced and repositioned the S-ICD lead from a left to a right parasternal site. After the re-implantation of the S-ICD, the DFT test improved to within normal range. According to the pathological analysis, infiltration of inflammatory cells and extensive fibrosis were confirmed in the subcutaneous tissue around the shock lead and S-ICD body.

Conclusion

Frequent S-ICD shocks for VF storms might cause various pathological changes around the device and lead to a high DFT.

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.

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

Aims

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

Methods and results

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

Conclusion

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

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.

Pharmacological Therapy in Brugada Syndrome

Brugada syndrome (BrS) is a cardiac disease caused by an inherited ion channelopathy associated with a propensity to develop ventricular fibrillation. Implantable cardioverter defibrillator implantation is recommended in BrS, based on the clinical presentation in the presence of diagnostic ECG criteria. Implantable cardioverter defibrillator implantation is not always indicated or sufficient in BrS, and is associated with a high device complication rate. Pharmacological therapy aimed at rebalancing the membrane action potential can prevent arrhythmogenesis in BrS. Quinidine, a class 1A antiarrhythmic drug with significant Ito blocking properties, is the most extensively used drug for the prevention of arrhythmias in BrS. The present review provides contemporary data gathered on all drugs effective in the therapy of BrS, and on ineffective or contraindicated antiarrhythmic drugs.

Brugada Syndrome:Risk Stratification And Management

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

The Brugada Syndrome - From Gene to Therapy

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

Brugada Syndrome: 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.

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.

Electrical storm in patients with brugada syndrome is associated with early repolarization

BACKGROUND

Electrical storms (ESs) in patients with Brugada syndrome (BrS) are rare though potentially lethal.

METHODS AND RESULTS

We studied 22 men with BrS and ES, defined as ≥3 episodes/d of ventricular fibrillation (VF) and compared their characteristics with those of 110 age-matched, control men with BrS without ES. BrS was diagnosed by a spontaneous or drug-induced type 1 pattern on the ECG in the absence of structural heart disease. Early repolarization (ER) was diagnosed by J waves, ie, >0.1 mV notches or slurs of the terminal portion of the QRS complex. The BrS ECG pattern was provoked with pilsicainide. A spontaneous type I ECG pattern, J waves, and horizontal/descending ST elevation were found, respectively, in 77%, 36%, and 88% of patients with ES, versus 28% (P<0.0001), 9% (P=0.003), and 60% (P=0.06) of controls. The J-wave amplitude was significantly higher in patients with than without ES (P=0.03). VF occurred during undisturbed sinus rhythm in 14 of 19 patients (74%), and ES were controlled by isoproterenol administration. All patients with ES received an implantable cardioverter defibrillator and over a 6.0±5.4 years follow-up, the prognosis of patients with ES was significantly worse than that of patients without ES. Bepridil was effective in preventing VF in 6 patients.

CONCLUSIONS

A high prevalence of ER was found in a subgroup of patients with BrS associated with ES. ES appeared to be suppressed by isoproterenol or quinidine, whereas bepridil and quinidine were effective in the long-term prevention of VF in the highest-risk patients.

Ventricular fibrillation associated with complete right bundle branch block

BACKGROUND

A substantial number of patients with idiopathic ventricular fibrillation (IVF) present with no specific electrocardiographic (ECG) findings.

OBJECTIVE

To evaluate complete right bundle branch block (RBBB) in patients with IVF.

METHODS

Patients with IVF showing complete RBBB were included in the present study. Structural and primary electrical diseases were excluded, and provocation tests were performed to exclude the presence of spastic angina or Brugada syndrome (BrS). The prevalence of complete RBBB and the clinical and ECG parameters were compared either in patients with IVF who did not show RBBB or in the general population and age and sex comparable controls with RBBB.

RESULTS

Of 96 patients with IVF, 9 patients were excluded for the presence of BrS. Of 87 patients studied, 10 (11.5%) patients showed complete RBBB. None had structural heart diseases, BrS, or coronary spasms. The mean age was 44 ± 15 years, and 8 of 10 patients were men. Among the ECG parameters, only the QRS duration was different from that of the other patients with IVF who did not show complete RBBB. Ventricular fibrillation recurred in 3:2 in the form of storms, which were well suppressed by isoproterenol. Complete RBBB was found less often in control subjects (1.37%; P < .0001), and the QRS duration was more prolonged in patients with IVF: 139 ± 10ms vs 150 ± 14ms (P = .0061).

CONCLUSIONS

Complete RBBB exists more often in patients with IVF than in controls. A prolonged QRS complex suggests a conduction abnormality. Our findings warrant further investigation of the role of RBBB in the development of arrhythmias in patients with IVF.

Ageing and Brugada syndrome: considerations and recommendations

Brugada syndrome is an inherited disease associated with an increased risk of lethal ventricular arrhythmias. Such arrhythmias stem from innate disruptions in cardiac electrophysiology. Typically, such arrhythmias occur in the third or fourth decade of life. However, Brugada syndrome may also affect geriatric patients. In this paper, we focus on the ageing patient with Brugada syndrome, and specifically, on the interaction between Brugada syndrome and the more usually acquired clinical problems that may occur with increasing age, such as the use of cardiovascular and non-cardiovascular drugs, or the need for surgery. Such common conditions may also disrupt cardiac electrophysiology, thereby conferring added risk for Brugada syndrome patients. We present some considerations and recommendations that may serve as guidance to address these complexities.