Brugada syndrome and "Brugada sign": clinical spectrum with a guide for the clinician

Long-Term Prognosis of Febrile Individuals with Right Precordial Coved-Type ST-Segment Elevation Brugada Pattern: A 10-Year Prospective Follow-Up Study

A febrile state may provoke a Brugada electrocardiogram (ECG) pattern and trigger ventricular tachyarrhythmias in susceptible individuals. However, the prognostic value of fever-induced Brugada ECG pattern remains unclear. We analyzed the clinical and extended long-term follow-up data of consecutive febrile patients with a type 1 Brugada ECG presented to the emergency department. A total of 21 individuals (18 males; mean age, 43.7 ± 18.6 years at diagnosis) were divided into symptomatic (resuscitated cardiac arrest in one, syncope in two) and asymptomatic (18, 86%) groups. Sustained polymorphic ventricular tachycardias were inducible in two patients with previous syncope. All 18 asymptomatic patients had no spontaneous type 1 Brugada ECG recorded at second intercostal space and no family history of sudden death. Among asymptomatic individuals, 4 had a total 12 of repeated non-arrhythmogenic febrile episodes all with recurrent type 1 Brugada ECGs, and none had a ventricular arrhythmic event during 116 ± 19 months of follow-up. In the symptomatic group, two had defibrillator shocks for a new arrhythmic event at 31- and 49 months follow-up, respectively, and one without defibrillator therapy died suddenly at 8 months follow-up. A previous history of aborted sudden death or syncope was significantly associated with adverse outcomes in symptomatic compared with asymptomatic individuals (log-rank p < 0.0001). In conclusion, clinical presentation or history of syncope is the most important parameter in the risk stratification of febrile patients with type 1 Brugada ECG. Asymptomatic individuals with a negative family history of sudden death and without spontaneous type 1 Brugada ECG, have an exceptionally low future risk of arrhythmic events. Careful follow-up with timely and aggressive control of fever is an appropriate management option.

Fever-Induced Brugada-Pattern Electrocardiogram

BACKGROUND

Brugada syndrome is an increasingly recognized syndrome characterized by a particular electrocardiography (ECG) pattern and clinical criteria and has a high incidence of sudden death in patients with structurally normal hearts. The Brugada ECG pattern can be unmasked by drugs, ischemia, and fever.

CASE REPORT

We present the case of a 47-year-old man who presented to the emergency department with flu-like symptoms and syncope. On arrival, he was febrile and his ECG showed a Brugada pattern. Although this pattern resolved once his fever resolved, the cardiologists were concerned that his syncopal episode might have been due to ventricular tachycardia/fibrillation, and the patient was admitted for implantable cardiac defibrillator placement. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Fever and other stressors can unmask a Brugada pattern on ECG, and if patients have concerning clinical criteria, they should receive emergent cardiology follow-up.

Hypothetical "anatomy" of Brugada phenomenon: "Long QT sine Long QT" syndrome implicating morphologically undefined specific "Brugada's myocells"

The Brugada syndrome (BrS) is associated with increased risk of ventricular arrhythmias and sudden cardiac death. It generates genetically mediated arrhythmias posing a true pathophysiological challenge. In search of the similarities between BrS and long QT syndrome some novel insights are suggested. In patients with BrS the duration of QT interval is usually normal. Some investigators have found prolonged QT interval in the syndrome's natural course or the duration of QT segment have been extended by provocative tests unmasking BrS. Thus, BrS might be characterized as "long QT sine long QT" syndrome. The existence of two functional types of myocites is suspected. Regarding structure and function the majority of ventricular myocardium is probably mostly healthy. The rest of myocardium (preferably the subepicardium of right ventricular outflow tract) due to its genotypic peculiarities demonstrates no negative influence on ventricular performance until early adulthood is reached and/or other unstable preconditions are fulfilled (nocturnal time, fever, specific drugs, etc.). Based on published findings of positive outcomes, following the epicardial ablation of the right ventricular outflow tract region, a new hypothetical concept suggesting the presence of specific, genetically affected "Brugada's myocells" is proposed. These cells as a suitable arrhythmogenic substrate reside intramurally within the subepicardial region of the outflow tract of right ventricle. In the daytime these cells likely are dormant but at rest their nocturnal proarrhythmic behavior is activated occasionally. Presumptions regarding the pathophysiology of BrS might be the focus of further discussion.

Intensive management of electrical storm and incessant ventricular arrhythmias

Electrical storm (ES) is defined as ventricular tachycardia or ventricular fibrillation occurring at least three times in 24 h leading to hemodynamic unstable state that needs cardioversion or defibrillation. ES may cause fast hemodynamic impairment, leading to “low-perfusion” or “no perfusion” state of the organs, a vicious circle pointing toward cardiogenic shock, multi-organ failure, and pulseless electrical activity. ES in ICD patients may be a strong predictor of arrhythmic and nonarrhythmic death, as well as of rehospitalization. The first step is to start cardiopulmonary resuscitation to achieve complete hemodynamic stabilization to prevent the low-flow or no-flow state. The patient has to be transported to an intensive care unit for further specific treatment. The arrhythmia should be treated with specific antiarrhythmic agents, for example, amiodarone, lidocain and bretylium, and then all the reversible causes have to be detected and treated as fast as possible. Underlying heart disease determines the specific treatment such as coronary revascularization, mechanical circulatory and respiratory support, and ablation of the arrhythmic foci.

Early repolarization syndrome and Brugada syndrome: is there any linkage?

Early repolarization syndrome (ERS) is characterized by the presence, in most cases in mid-to-lateral precordial leads, of a J wave on the downsloping portion of the QRS complex, followed by an elevation of the ST-segment with upward concavity. ERS is considered a benign electrocardiographic pattern of ventricular repolarization and, thus far, clinical interest in this syndrome has been confined to its differential diagnosis from myocardial infarction and pericarditis. Brugada syndrome (BS), an inherited cardiac disease first described in 1992, exhibits a characteristic electrocardiographic pattern consisting of a J wave mimicking a right bundle branch block with typical ST-segment elevation in the right precordial leads. Believed to be a normal repolarization variant for more than three decades, the syndrome is now known instead to be associated with a high incidence of life-threatening ventricular tachyarrhythmias and is responsible for a number of sudden deaths in young adults worldwide. Although clinical findings seem to differentiate the two syndromes, similarities between BS and ERS in terms of response to heart rate, pharmacologic agents, and neuromodulation could suggest a linkage in their pathophysiological mechanism. The authors review the clinical and experimental data in order to test this hypothesis.

Functionally distinct sodium channels in ventricular epicardial and endocardial cells contribute to a greater sensitivity of the epicardium to electrical depression

A greater depression of the action potential (AP) of the ventricular epicardium (Epi) versus endocardium (Endo) is readily observed in experimental models of acute ischemia and Brugada syndrome. Endo and Epi differences in transient outward K(+) current and/or ATP-sensitive K(+) channel current are believed to contribute to the differential response. The present study tested the hypothesis that the greater sensitivity of Epi is due in part to its functionally distinct early fast Na(+) current (I(Na)). APs were recorded from isolated Epi and Endo tissue slices and coronary-perfused wedge preparations before and after exposures to elevated extracellular K(+) concentration ([K(+)](o); 6-12 mM). I(Na) was recorded from Epi and Endo myocytes using whole cell patch-clamp techniques. In tissue slices, increasing [K(+)](o) to 12 mM reduced V(max) to 51.1 +/- 5.3% and 26.8 +/- 9.6% of control in Endo (n = 9) and Epi (n = 14), respectively (P < 0.05). In wedge preparations (n = 12), the increase in [K(+)](o) caused selective depression of Epi APs and transmural conduction slowing and block. I(Na) density was not significantly different between Epi (n = 14) and Endo (n = 15) cells, but Epi cells displayed a more negative half-inactivation voltage [-83.6 +/- 0.1 and -75.5 +/- 0.3 mV for Epi (n = 16) and Endo (n = 16), respectively, P < 0.05]. Our data suggest that reduced I(Na) availability in ventricular Epi may contribute to its greater sensitivity to electrical depression and thus may contribute to the R-ST segment changes observed under a variety of clinical conditions including acute myocardial ischemia, severe hyperkalemia, and Brugada syndrome.

[Acute inferior myocardial infarction masking the J wave syndrome. Based on four observations]

The J wave syndrome is characterized by a prominent J wave accompanied by ST-segment elevation in the absence of structural heart disease. It includes the benign early repolarization syndrome, the highly arrhythmogenic Brugada syndrome and idiopathic ventricular fibrillation. Although acute coronary syndromes are one of the leading causes of ST-segment deviation, no clinical reports that specifically describe the modulating effects of an ischemic injury current on the ECG manifestations of the J wave syndrome have been found. This report describes four cases of patients with acute inferior ST-segment elevation myocardial infarction who had J wave (or negative deplacement of the J point) and ST-segment depression in the right precordial leads. Later, these precordial ECG alterations disappeared and were progressively replaced by prominent J (R') waves and anterior ST-segment elevations, suggesting the presence of a J wave syndrome. In conclusion, the J wave syndrome may be obscured by an acute inferior myocardial infarction with concomitant ST-segment depression in the right precordial leads. In such circumstances, early detection of the J wave (or depressed J point) may be used as ECG marker of the early repolarization syndrome or Brugada syndrome.

Frequency of Brugada-type ECG pattern (Brugada sign) in Southern Turkey

The frequency of Brugada sign was found to differ among ethnic groups. Yet, there is no data regarding the prevalence of Brugada syndrome and sign in our country. The aim of this study was to determine the frequency of a Brugada-type electrocardiogram (ECG) pattern in southern Turkey. A total of 1,238 subjects (males, 671, females, 567) were included in the study. The previously archived ECGs of 807 subjects without any evidence of structural heart disease were chosen randomly and evaluated. In addition, prospective analysis of the ECGs of 431 subjects (males, 293, females, 138) randomly chosen from healthy university students were also included. The mean age was 38.9 +/- 17.6 years. Six subjects (0.48%) had a Brugada-type ECG pattern. One (0.08%) of them had the coved-type and 5 (0.40%) had the saddleback-type. All subjects were asymptomatic. A Brugada-type ECG pattern was obtained in 1 (0.17%) female and in 5 (0.74%) males (OR: 4.2 CI: 0.5-36.4, P = 0.2). The Brugada-type ECG pattern frequency was 0.12% in subjects >or= 25 years old and 1.16% in subjects between 17-24 years old (OR: 9.4 CI: 1.1-81.2, P = 0.02). Young males between 17-24 years had the highest (1.70%) frequency. The results indicate that the frequency of the Brugada-type ECG pattern was 0.48% in the general population, being more prevalent in young males in our region. These results are similar to the findings of studies performed in other countries.

The electrocardiogram in the patient with syncope

Syncope is a common and challenging presentation for the emergency physician. Various investigators have developed clinical risk score and clinical decision rules which are designed to identify the population at highest risk for adverse events. In each of these clinical decision tools, the electrocardiogram (ECG) is one of the key clinical variables used to evaluate the patient. Certain electrocardiographic presentations in the patient with syncope will not only provide a reason for the loss of consciousness but also guide early therapy and disposition in this individual. Bradycardia, atrioventricular block, intraventricular conduction abnormality, and tachydysrhythmia in the appropriate clinical setting provide an answer to the clinician for the syncopal event. Morphologic findings suggesting the range of cardiovascular malady are also encountered; these entities are far ranging, including the various ST-segment and T-wave abnormalities of acute coronary syndrome, ventricular preexcitation as seen in the Wolff-Parkinson-White syndrome, Brugada syndrome with the associated tendency for sudden death, prolonged QT interval common in the diverse long QT interval presentations, and right ventricular hypertrophy suggestive of hypertrophic cardiomyopathy. This review discusses the ECG in the patient with syncope. The general use of the 12-lead ECG in this patient population is discussed. Furthermore, specific electrocardiographic presentations seen in the patient with syncope are also reviewed.

The hyperkalemic Brugada sign

BACKGROUND

A few case reports have indicated that hyperkalemia can induce a Brugada pattern in the electrocardiogram. The specific clinical and electrocardiographic features of the hyperkalemic Brugada sign, however, have not been previously described.

METHODS

A case series was collected from hospitalized hyperkalemic patients with a type I Brugada pattern in the electrocardiogram, and a literature review was performed. Electrocardiograms were examined for rhythm and morphology, and clinical characteristics were analyzed.

RESULTS

Nine new cases with the hyperkalemic Brugada sign were identified with an additional 15 cases found in the literature. Of the 9 cases, 8 were male patients, and all were critically ill; 5 of the 9 died within 48 hours. The mean (+/-SD) serum potassium level was 7.8 +/- 0.5 mEq/L. The mean QRS width was 144 +/- 31 milliseconds, and all had abnormal QRS axis. In 6 cases, there was a wide complex rhythm without visible P waves. The clinical and electrocardiographic characteristics of 15 cases found in the literature were remarkably similar to those in our series.

CONCLUSIONS

The hyperkalemic Brugada pattern differs in substantial ways from the electrocardiogram of patients with the genetic Brugada syndrome. Many patients have wide complex rhythms without visible P waves, marked QRS widening, and an abnormal QRS axis. Most patients are male, and many are critically ill. Prompt recognition of this clinical and electrocardiographic entity may expedite the initiation of appropriate treatment for hyperkalemia.

Syncope due to Brugada syndrome in a young athlete

A 30-year-old male athlete with exercise-related syncopal symptoms spontaneously exhibited a type 1 Brugada ECG and was inducible during electrophysiology study. He was diagnosed with symptomatic Brugada syndrome and deemed at high risk of sudden cardiac death. Thus, he received a cardioverter/defibrillator and was advised to abstain from further competitive sports activities. This case points to a role of the ECG in pre-participation screening. It also demonstrates that, in athletes with Brugada syndrome, repolarisation anomalies may be markedly attenuated during vigorous exercise and considerably increased immediately after exercise. The observed J-wave amplitude dynamics suggests enhancement of pre-existing autonomic dysfunction through heavy exertion.

Brugada electrocardiographic pattern due to tricyclic antidepressant overdose

The Brugada syndrome is an arrhythmogenic disease with characteristic coved ST-segment elevation 2 mm or greater in the right precordial leads (type 1 Brugada electrocardiogram [ECG] pattern or "Brugada sign"] and is estimated to be responsible for at least 20% of sudden deaths in patients with structurally normal hearts [Circulation 2005;111(5):659-70]. The Brugada sign has been described in asymptomatic patients after exposure to various drugs. As published reports of the drug-induced Brugada sign have become increasingly prevalent, there is growing interest in the mechanisms responsible for this acquired ECG pattern and its clinical significance. We report a case of a patient who developed the type 1 Brugada ECG pattern after intentional overdose of a tricyclic antidepressant agent, review the literature concerning tricyclic antidepressant agent-induced Brugada sign, discuss potential mechanisms, and evaluate the clinical significance of this ECG abnormality.

Brugada-like electrocardiographic pattern: a challenge for the clinician

A right bundle branch block with ST-segment elevation in the V1-V3 leads in characteristic coved or saddleback configuration may be encountered as an incidental finding. However, not all patients with a Brugada-like electrocardiographic pattern are affected by the Brugada syndrome; in fact, this pattern may also be found in healthy individuals. Whether symptomatic patients affected by the syndrome are at a high risk of developing life-threatening ventricular arrhythmias and should immediately receive an automatic, implantable defibrillator is open to debate, as is the clinical management of asymptomatic patients, because data from the scientific literature are controversial. Implications of the diagnosis and the treatment of this category of patients are discussed.

Prevalence of the Brugada-type ECG recorded from higher intercostal spaces in healthy Korean males

BACKGROUND

Electrocardiograms (ECGs) recorded from the higher intercostal spaces (ICSs) are reported to be helpful for the diagnosis of Brugada syndrome (BS). However, the prevalence of Brugada-type ECG changes recorded from the higher ICSs is unknown in the healthy Korean population.

METHODS AND RESULTS

A total of 225 healthy Korean male subjects with a mean age of 44+/-13 (20-69) years with no syncope or family history of sudden death were enrolled in the present study. ECGs were taken from 4th, 3rd, and 2nd ICSs and examined for Brugada-type ECG changes. There were none on the routine 12-lead ECGs, but 3 (1.3%) of the 225 subjects had a Brugada-type ECG recorded from the higher ICSs and 1 of them had a Brugada-type ECG recorded at both the 2nd and 3rd ICSs. The prevalence of the Brugada-type ECG was 1.3% at the 3rd ICS, 0.4% at the 2nd ICS. All were type 2.

CONCLUSION

Some healthy Korean males with normal routine ECGs show Brugada-type 2 changes on ECGs recorded from higher ICSs.

Diphenhydramine overdose and Brugada sign

We report a case of electrocardiographic signature of the Brugada syndrome in a 39-year-old patient with an overdose of diphenhydramine. He was found unconscious and hypotensive. His serum potassium concentration was 8.3 mEq/L and the ECG revealed a coved-type ST-segment elevation in leads V2-V3. These repolarization abnormalities neither normalize with the correction of the hyperkalemia nor with an intravenous infusion of isoproterenol. When he regained consciousness, he was admitted the toxic ingestion of diphenhydramine and progressively the ECG normalized. A negative flecainide test confirmed that the transient ECG abnormalities were the consequence of the drug overdose and ruled out the Brugada syndrome.

Brugada Syndrome Mimicking Acute Coronary Syndrome

This report describes a 42-year-old man with Brugada syndrome (BRS) mimicking acute coronary syndrome. Chest pain, near-syncope, and electrocardiographic changes were thought initially to be due to ischemia. Cardiac catheterization was performed. The coronary arteries and left ventricular function were normal. Careful review of his electrocardiogram suggested a diagnosis of BRS. BRS may be confused with acute coronary syndrome; early recognition of this syndrome is essential, as implantable cardioverter-defibrillator therapy may be life-saving.

[Indications for automatic implantable defibrillators in patients with the Brugada syndrome]

Brugada syndrome is a primary electrical cardiac disease characterized by an ST segment elevation in V1-V2 leads on surface ECG and an increased risk of polymorphic ventricular tachyarrhythmia (ventricular tachycardia and/or ventricular fibrillation). The objective of the treatment is to prevent sudden death and it therefore includes in some cases the implantation of an automatic implantable cardiac defibrillator (AICD). In secondary prevention (i.e. after a first episode of resuscitated ventricular fibrillation), the implantation of AICD is mandatory (indication of class 1 level A). In primary prevention (i.e. in patients without documented ventricular fibrillation), the guidelines are not definitively established. We may consider two different clinical situations. First, the patient complains from syncope and this justifies the implantation of an AICD. Second, the patient is asymptomatic and the physician has to discuss the implantation of an AICD. Two parameters should be analysed: the pattern of ECG and the result of right programmed ventricular stimulation. An evident ST segment elevation (>2 mm) is associated with a high risk of sudden death. Likewise, the inducibility of a ventricular tachycardia or fibrillation is considered at the present time as a factor linked to sudden death and justifies the implantation of an AICD. On the other hand, a normal resting ECG only associated with a provoked ST segment elevation by class I antiarrhythmic drug (flecainide) defines a group of patients with a low risk of sudden death, and these patients do not require the implantation of an AICD.

Brugada Electrocardiographic Pattern Elicited by Inadvertent Flecainide Overdose

In a 70-year-old man, without clinical suggestion of the hereditary form of the Brugada syndrome, severe flecainide overdose resulted in profound widening of the QRS complex and the development of ST-T abnormalities typical of the Brugada sign. Serial ECGs recorded over a 5-day period revealed a parallel pattern of dynamic intraventricular conduction defect and ST-segment elevation. Resolution of ST-segment elevation lagged behind resolution of the QRS widening by 16-20 hours. Despite the marked Brugada abnormality no arrhythmia occurred and the patient recovered without complications.

Idiopathic Brugada-type electrocardiographic pattern in an octogenarian

The prognosis of idiopathic Brugada-type ECG pattern in asymptomatic people is unknown. We report a case of an 85-year-old man who had persistent Brugada-type ECG pattern without associated clinical symptoms. This illustrates that the persistent Brugada-type ECG can be present with normal longevity.