Clinical and electrophysiological profile of Brugada syndrome in the Tunisian population

Background: Most clinical studies of the clinical profile of Brugada syndrome (BS) have been conducted in either Asia, Europe, or America and their applicability to North African populations is largely unknown. The aim of the study was to analyze the clinical profile of BS in Tunisian patients. Methods: The clinical and follow‐up data of 24 patients (22 men, mean age: 40.8 ± 13.7 years) were collected since 2002. Baseline characteristics, morbidity, and mortality data were obtained from medical records. Results: One patient (4.16%) survived sudden cardiac death (SCD), four patients (16.3%) had syncope, and 19 patients (79.1%) were asymptomatic. Eleven patients (45.8%) had a family history of SCD. Twenty patients showed a spontaneous coved‐type ST‐segment elevation on electrocardiogram and after medical challenge on the four remnants. An electrophysiological study was performed in 15 of 24 patients (62.5%), during which ventricular fibrillation was induced in six patients (40%); three of the six patients were previously asymptomatic. An implantable cardioverter defibrillator (ICD) was implanted in 14 patients (58.3%). After a mean follow‐up of 26 ± 21 months, one patient died from a noncardiac cause and one patient (with a history of aborted SCD) received an appropriate shock from his ICD. None of the asymptomatic and noninducible patients experienced a cardiac event. Conclusions: BS is present in the North African population and is probably under‐recognized. Tunisian patients with BS share with their western and Asiatic counterparts similar clinical profile. (PACE 2011; 47–53)     

Syncope with ST-segment abnormalities resembling Brugada syndrome due to reversible myocardial ischemia

This report describes a case of syncope with an initial ECG that showed ST-segment elevation in the right precordial leads suggestive of Brugada syndrome. Procainamide infusion induced a significant increase in the ST-segment abnormalities, further increasing the suspicion for this syndrome. Cardiac catheterization showed lesions in the proximal left anterior descending artery and distal right coronary artery. Following percutaneous coronary intervention at these sites, the ST-segment abnormalities resolved and a repeat procainamide challenge was negative. Electrophysiological study did not provoke any ventricular arrhythmias. Silent myocardial ischemia may result in ECG changes that resemble those seen in patients with Brugada syndrome.     

Drug‐Induced Brugada Syndrome by Noncardiac Agents

Drug‐induced Brugada syndrome (BrS) represents a great challenge for the prescribing clinicians as well as for those involved in the development of novel pharmaceuticals and in the regulatory bodies responsible with monitoring drug safety. Apart from well‐known cardiac agents (mainly Class I antiarrhythmics), an increasing number of noncardiac agents, including psychotropic and anesthetic drugs, have been shown to induce the characteristic Brugada electrocardiogram pattern predisposing to fatal ventricular arrhythmias. Up to now, both repolarization and depolarization abnormalities are thought to be related to the development of ventricular fibrillation in BrS patients. This review highlights the mechanisms and the noncardiac medical agents that unmask a genetic predisposition to BrS.     

Prognosis, risk stratification,and management of asymptomatic individuals with Brugada syndrome: A systematic review

Brugada syndrome (BrS) is a primary electrical disease associated with increased risk of sudden cardiac death due to polymorphic ventricular arrhythmias. The prognosis, risk stratification, and management of asymptomatic individuals remain the most controversial issues in BrS. Furthermore, the decision to manage asymptomatic patients with an implantable cardioverter‐defibrillator should be made after weighing the potential individual risk of future arrhythmic events against the risk of complications associated with the implant and follow‐up of patients living with such devices, and the accompanying impairment of the quality of life. Several clinical, electrocardiographic, and electrophysiological markers have been proposed for risk stratification of subjects with BrS phenotype, but the majority have not yet been tested in a prospective manner in asymptomatic individuals. Recent data suggest that current risk factors are insufficient and cannot accurately predict sudden cardiac death events in this setting. This systematic review aims to discuss contemporary data regarding prognosis, risk stratification, and management of asymptomatic individuals with diagnosis of Brugada electrocardiogram pattern and to delineate the therapeutic approach in such cases.     

Brugada Syndrome: A Primer for Nurse Practitioners

Brugada syndrome (BrS) is a less known cardiac condition which falls into the category of a channelopathies. BrS has been diagnosed for more than 2 decades. Currently BrS remains a major cause of sudden cardiac death in young adults who have no known abnormal heart structure. Nurse practitioners’ awareness of the clinical presentation, diagnosis, treatment, and ongoing care is essential for maximizing patient outcomes.     

True right bundle branch block masking the typical ECG in Brugada syndrome

A patient with a family history of sudden cardiac death and a structurally normal heart presented with a resting ECG intermittently displaying a saddle-type Brugada-ECG, which could be reproducibly converted to a coved-type ECG pattern suggestive of Brugada syndrome. However, no ST-segment changes occurred in the presence of a true right bundle branch block (RBBB) in the same patient. In consideration of the inalienable diagnostic criterion of dynamic ECG abnormalities in the right precordial leads in Brugada syndrome, setting the diagnosis in patients with true RBBB may be unattainable.     

Arrhythmic storm responsive to quinidine in a patient with Brugada syndrome and vasovagal syncope

A 37-year-old man with Brugada syndrome (BrS) and arrhythmic storm is described. One month after implantation of a cardioverter-defibrillator he presented with recurrent appropriate shocks for spontaneous ventricular fibrillation (VF). Because of this arrhythmic storm, quinidine therapy was initiated with total suppression of all spontaneous arrhythmias. He had remained free of arrhythmias for 22 months since quinidine initiation. Two episodes of VF occurred after the patient stopped taking the medication. The patient resumed quinidine and has been free of VF for the last 3 months. This response to quinidine in a patient with symptomatic BrS supports its role in the prophylaxis of arrhythmic events in BrS.     

Brugada syndrome in children

Brugada syndrome is an inherited arrhythmia associated with characteristic ST elevation in the right precordial leads and sudden cardiac death. The average age of sudden cardiac death is 40 years; reported pediatric cases remain rare. Genetic testing and increased disease awareness may result in many more children being diagnosed with Brugada syndrome.     

Flecainide Test in Brugada Syndrome: A Reproducible but Risky Tool

GASPARINI, M., et al .: Flecainide Test in Brugada Syndrome: A Reproducible but Risky Tool. The flecainide test is widely used in Brugada syndrome. However, its reproducibility and safety remain ill-defined. This study included 22 patients (18 men, mean age 34 years). Mutations in the SCN5A gene were found in eight patients. Two patients had aborted sudden cardiac death, 8 had syncope/presyncope, and 12 were asymptomatic. The ECG was diagnostic in 19 patients and suggestive in 3. At baseline, 21 of 22 patients underwent a flecainide test (2 mg/kg IV bolus over 10 minutes). In 21 of 21 patients the test was diagnostic or amplified the typical ECG pattern. At the end of drug infusion, sustained VT lasting 7–10 minutes developed in two patients. A second flecainide test was performed within 2 months in 20 patients. The test was not repeated in the two patients with prior development of VT. The flecainide test was diagnostic in 20 of 20 patients. Sustained VT occurred in one patient and recurrent VF in another. The reproducibility of the flecainide test was 100%. In 4 (18%) of 22 patients major VAs were documented after the end of flecainide infusion. VA occurred in 3 (43%) of 7 patients with, versus 1 (7%) 15 without SCN5A gene mutation (P < 0.05). No diagnostic ECG changes or arrhythmias developed in 25 control patients without structural heart disease who underwent the same study protocol. This study shows a high flecainide reproducibility, supporting its diagnostic value in Brugada syndrome. However, the occurrence of major VA, significantly higher in patients with documented SCN5A gene mutation, including in asymptomatic patients, mandates the performance under appropriate medical supervision. Whether a slower rate of drug infusion can lower the risk of VA induction, while maintaining the sensitivity of the test should be explored. (PACE 2003; 26[Pt. II]:338–341)     

Recovery Following Propofol‐Associated Brugada Electrocardiogram

Brugada syndrome is a genetic disorder associated with an increased risk of sudden cardiac death that has typical electrocardiographic (ECG) patterns. Recently, there have been reports of Brugada ECG patterns seen in critically ill patients who received propofol, 1 and this pattern was associated with a very high imminent mortality. We report a case in which a critically ill patient developed a Brugada ECG pattern following high‐dose propofol infusion. Once the ECG pattern was recognized, the propofol was discontinued and the ECG pattern resolved, and the patient was discharged home with no arrhythmic sequelae.     

Novel spectral indexes of heart rate variability as predictors of sudden and non‐sudden cardiac death after an acute myocardial infarction

Background. Various indexes of 24‐hour heart rate variability (HRV) have been able to predict all‐cause mortality after an acute myocardial infarction (AMI), but their value in predicting specific modes of cardiac death has been limited.

Aim. The aim of this study was to assess the role of two novel spectral indexes of HRV as predictors of either sudden (SCD) or non‐sudden cardiac death after an AMI.

Method. We used two novel methods of spectral analysis of HRV: 1) the high‐frequency (HF) spectral component, V_index, calculated as an average HF power from the most linear portion of HF power versus the R‐R interval regression curve, and 2) the prevalent low‐frequency oscillation of heart rate (PLF). V_index, conventional HRV measures, and PLF were analyzed from 24‐hour Holter recordings of 590 patients with a recent AMI.

Results. During the mean follow‐up of 39±14 months, SCD occurred in 3% (n = 17) and non‐sudden cardiac death in 5% (n = 28) of the patients. In univariate analysis, V_index was the most potent predictor of SCD (RR: 6.0, 95% CI: 1.7–20.7, P<0.01), also remaining the most powerful predictor of SCD after adjustment for clinical variables and ejection fraction (RR: 4.2, 95% CI: 1.2–15.2, P<0.05). PLF was a potent predictor of non‐sudden cardiac death (RR: 13.9, 95% CI: 5.9–32.5, P<0.001), but it did not predict SCD.

Conclusions. Novel spectral HRV analysis methods, V_index and PLF, provide significant information of the risk of the specific mode of death after an AMI.     

Brugada syndrome

First introduced as a new clinical entity in 1992, the Brugada syndrome is associated with a relatively high risk of sudden death in young adults, and occasionally in children and infants. Recent years have witnessed a striking proliferation of papers dealing with the clinical and basic aspects of the disease. Characterized by a coved-type ST-segment elevation in the right precordial leads of the electrocardiogram (ECG), the Brugada syndrome has a genetic basis that thus far has been linked only to mutations in SCN5A, the gene that encodes the alpha-subunit of the sodium channel. The Brugada ECG is often concealed, but can be unmasked or modulated by a number of drugs and pathophysiological states including sodium channel blockers, a febrile state, vagotonic agents, tricyclic antidepressants, as well as cocaine and propranolol intoxication. Average age at the time of initial diagnosis or sudden death is 40 +/- 22, with the youngest patient diagnosed at 2 days of age and the oldest at 84 years. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of the Brugada syndrome, incorporating the results of two recent consensus conferences. Controversies with regard to risk stratification and newly proposed pharmacologic strategies are discussed.     

Prevalence of electrocardiographic findings suggestive of sudden cardiac death risk in 10,867 apparently healthy young Korean men

Background: The objective of this study was to determine the prevalence of electrocardiographic (ECG) findings suggestive of sudden cardiac death risk in apparently healthy young Korean men. Methods: We administered questionnaires that elicited personal and family histories and performed ECGs on 10,867 male subjects (mean age, 20.9 years). The subjects with abnormal ECG findings underwent echocardiography, a treadmill test, Holter monitoring, a flecainide provocation test, or an electrophysiologic study (EPS) according to the ECG findings and histories. Results: Of the subjects, 5.95% had left ventricular hypertrophy on ECG, but no subjects had hypertrophic cardiomyopathy by echocardiography. The percentage of subjects with a Brugada ECG pattern was 0.90%. We identified one subject with a positive result on the flecainide provocation test. The percentage of subjects with a preexcitation ECG was 0.17%. In two of the subjects, supraventricular tachycardia was induced in the EPS. Of the subjects, 0.05% had epsilon waves, but there were no subjects with arrhythmogenic right ventricular dysplasia/cardiomyopathy by echocardiography. The percentage of subjects with long QT intervals was 0.02%, but there were no arrhythmias on the treadmill test or Holter monitoring. Conclusions: The prevalence of a Brugada ECG pattern in apparently healthy young men is higher in Korea than other countries. (PACE 2011; 717–723)     

Wolff-Parkinson-White syndrome concomitant with asymptomatic Brugada syndrome

A 29-year-old man was referred for electrophysiological testing and radiofrequency ablation because of repeated episodes of palpitation over 2 years. A 12-lead electrocardiogram during sinus rhythm showed manifest Wolff-Parkinson-White syndrome and during palpitation showed narrow QRS tachycardia at a rate of 213 beats/min. Following successful radiofrequency ablation of the left anterolateral accessory pathway, sustained atrial fibrillation was induced by atrial extrastimulation. Cibenzoline (2 mg/kg body weight) was injected to terminate atrial fibrillation. ST-T segment elevation in the right precordial leads was observed following cibenzoline administration. Ventricular fibrillation was reproducibly induced by ventricular extrastimuli (S1: 600 ms, S2: 220 ms, S3: 210 ms).     

Pericarditis mimicking Brugada syndrome

Introduction

Brugada syndrome (BrS) is a genetic heart disorder due to alteration of the ion channels function that causes an impaired in the cardiac conduction system. It is characterized by an abnormal electrocardiogram pattern and may be complicated by malignant ventricular arrhythmias.Pericarditis is an inflammation of the pericardium and 90% of isolated cases of acute pericarditis are idiopathic or viral. Acute pericarditis may appears with chest pain, fever, pericardial friction rub, and cardiac tamponade. Moreover, widespread ST segment changes occur due to involvement of the underlying epicardium.

Respiratory sinus arrhythmia as a predictor of sudden cardiac death after myocardial infarction

Background. Measurement of high-frequency (HF) spectral power of heart rate (HR) variability has not been able to identify the patients at risk of sudden cardiac death (SCD) despite the experimental evidence of protective role of vagal activity for fatal arrhythmias.

Aim. We developed a novel respiratory sinus arrhythmia (RSA) analysis method and tested its ability to predict SCD after an acute myocardial infarction.

Method. The RSA analysis method was developed in 13 subjects from simultaneous recordings of respiration and R-R intervals. An adaptive threshold was computed based on the zero-phase forward and reverse digital filtering in the analysis of RSA. With this method, only respiration-related R-R interval fluctuations are included. The prognostic power of RSA, analyzed from 24-hour electrocardiographic recordings, was subsequently assessed in a large postinfarction population including 1631 patients with mean follow-up of 40±17 months.

Results. Depressed RSA was a strong predictor of SCD (hazard ratio 7.4; 95% CI 3.6–15.1; P <0.0001) but only a weak predictor of non-SCD. The RSA index remained an independent predictor of SCD after adjustments for ejection fraction and other clinical risk variables (RR 4.7; 95% CI 2.28–9.85).

Conclusions. Reduced respiratory-related HR dynamics, detected by RSA index, are a specific marker of an increased risk of SCD among postinfarction patients.