Proposed Diagnostic Criteria for the Brugada Syndrome
2002; Lippincott Williams & Wilkins; Volume: 106; Issue: 19 Linguagem: Inglês
10.1161/01.cir.0000034169.45752.4a
ISSN1524-4539
AutoresArthur A.M. Wilde, Charles Antzelevitch, Martin Borggrefe, Josép Brugada, Ramón Brugada, Pedro Brugada, Domenico Corrado, Richard N.W. Hauer, Robert S. Kass, Koonlawee Nademanee, Silvia G. Priori, Jeffrey A. Towbin,
Tópico(s)ECG Monitoring and Analysis
ResumoHomeCirculationVol. 106, No. 19Proposed Diagnostic Criteria for the Brugada Syndrome Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBProposed Diagnostic Criteria for the Brugada SyndromeConsensus Report Arthur A.M. Wilde, Charles Antzelevitch, Martin Borggrefe, Josep Brugada, Ramón Brugada, Pedro Brugada, Domenico Corrado, Richard N.W. Hauer, Robert S. Kass, Koonlawee Nademanee, Silvia G. Priori, Jeffrey A. Towbin and Arthur A.M. WildeArthur A.M. Wilde From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Charles AntzelevitchCharles Antzelevitch From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Martin BorggrefeMartin Borggrefe From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Josep BrugadaJosep Brugada From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Ramón BrugadaRamón Brugada From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Pedro BrugadaPedro Brugada From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Domenico CorradoDomenico Corrado From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Richard N.W. HauerRichard N.W. Hauer From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Robert S. KassRobert S. Kass From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Koonlawee NademaneeKoonlawee Nademanee From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Silvia G. PrioriSilvia G. Priori From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author , Jeffrey A. TowbinJeffrey A. Towbin From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author and From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Interuniversity Cardiology Institute, The Netherlands (A.A.M.W.); Masonic Medical Research Laboratory, Utica, NY, (C.A.); Fakultät Klinische Medizin Mannheim, Universität Heidelberg, Mannheim, Germany (M.B.); Cardiovascular Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B.); Baylor College of Medicine, Houston, Tex (R.B.); Cardiovascular Center, Onze Lieve Vrouwe Ziekenhuis, Aalst, Belgium (P.B.); Divisione di Cardiología, Università di Padova, Padova, Italy (D.C.); Heart-Lung Center Utrecht, University Medical Center, Utrecht, The Netherlands (R.N.W.H.); Department of Pharmacology, Columbia University, New York, NY (R.S.K.); Division of Cardiology, University of Southern California, Los Angeles (K.N.); Molecular Cardiology and Electrophysiology Laboratories, Fondazione Salvatore Maugeri, Pavia, Italy (S.G.P.); and Department of Pediatrics, Baylor College of Medicine, Houston, Tex (J.A.T.). Search for more papers by this author and for the Study Group on the Molecular Basis of Arrhythmias of the European Society of Cardiology Originally published5 Nov 2002https://doi.org/10.1161/01.CIR.0000034169.45752.4ACirculation. 2002;106:2514–2519Asyndrome characterized by ST-segment elevation in right precordial leads (V1 to V3) that is unrelated to ischemia, electrolyte disturbances, or obvious structural heart disease was reported as early as 1953,1 but was first described as a distinct clinical entity associated with a high risk of sudden cardiac death in 1992.2–4 The Brugada syndrome is a familial disease that displays an autosomal dominant mode of transmission, with incomplete penetrance and an incidence ranging between 5 and 66 per 10 000. In regions of Southeast Asia where it is endemic, the clinical presentation of Brugada syndrome is distinguished by a male predominance (8:1 ratio of male:female) and the appearance of arrhythmic events at an average age of 40 years (range: 1 to 77 years).2,5 Although a number of candidate genes are considered plausible, thus far the syndrome has been linked only to mutations in SCN5A, the gene encoding for the α subunit of the sodium channel.6A number of ambiguities exist concerning the diagnosis of Brugada syndrome. The electrocardiographic signature of the syndrome is dynamic and often concealed, but can be unmasked by potent sodium channel blockers such as flecainide, ajmaline, and procainamide,7 although the specificity of this effect for uncovering patients at risk for sudden death has been an issue of concern. A recent report by Remme et al8 has shown that the number of idiopathic ventricular fibrillation patients diagnosed as having Brugada syndrome is a sensitive function of the diagnostic criteria applied. What are the proper diagnostic criteria for identifying Brugada syndrome? A definitive answer to this question has been out of reach and is the reason for the establishment of a special Arrhythmia Working Group of the European Society of Cardiology that met from August 31 to September 1, 2000. This report is the consensus statement from that meeting. The diagnostic criteria described herein are based on the currently available clinical data and state-of-the-art understanding of the molecular and cellular mechanisms underlying Brugada syndrome. The proposed criteria must be considered a work in progress that will be fine-tuned as confirmatory data from future molecular studies and prospective trials become available.Electrocardiographic CharacteristicsECG abnormalities constitute the hallmark of Brugada syndrome. They include repolarization and depolarization abnormalities in the absence of identifiable structural cardiac abnormalities or other conditions or agents known to lead to ST-segment elevation in the right precordial leads (Table 1). Three types of repolarization patterns are recognized (Figure 1). Type 1, described in a 1992 article,2 is characterized by a prominent coved ST-segment elevation displaying J wave amplitude or ST-segment elevation ≥2 mm or 0.2 mV at its peak followed by a negative T-wave, with little or no isoelectric separation. Type 2 also has a high take-off ST-segment elevation, but in this case, J wave amplitude (≥2 mm) gives rise to a gradually descending ST-segment elevation (remaining ≥1 mm above the baseline), followed by a positive or biphasic T-wave that results in a saddle back configuration. Type 3 is a right precordial ST-segment elevation of <1 mm of saddle back type, coved type, or both. It should be stressed that delineation of the J wave is sometimes tricky (second ECG in Figure 1) and that these descriptions are based on the correct placement of the precordial leads, although characteristic ECG features obtained with alternative placement of the right precordial leads in a superior intercostal space in individuals with high clinical suspicion (aborted sudden cardiac death victims, family members of patients with Brugada syndrome) may also disclose the presence of the arrhythmic substrate.9 In select cases one may even consider rightward displacement. However, the r′ deflection in leads V3R, V4R, etc, should be interpreted with caution. Characteristic ECG morphologies recorded in the first few hours after resuscitation or immediately after DC shock cannot be taken as diagnostic of the Brugada syndrome. As shown in Figure 1, the ST segment is dynamic. Different patterns may be observed sequentially in the same patient or following the introduction of specific drugs (see below). TABLE 1. ST-Segment Abnormalities in Leads V1 to V3Type 1Type 2Type 31 mm=0.1 mV. The terminal portion of the ST segment refers to the latter half of the ST segment.J wave amplitude≥2 mm≥2 mm≥2 mmT wavenegativepositive or biphasicpositiveST-T configurationcoved typesaddlebacksaddlebackST segment (terminal portion)gradually descendingelevated ≥1 mmelevated 2 mm absolute amplitude in lead V1 and/or V2 and/or V3 with or without RBBB is considered positive. In patients with type 1 ECGs, drug testing is not of additional diagnostic value. In patients with type 2 and type 3 ECGs, the test is recommended to clarify the diagnosis. Conversion of a type 2 or 3 ECG to a type 1 is considered positive (Figure 2). An increase in the J-wave amplitude of more than 2 mm without the development of a type 1 configuration is also considered significant, but in our experience is rarely observed. Conversion of type 3 ECG into type 2 is considered inconclusive. Download figureDownload PowerPointFigure 2. ECGs from a 35-year-old male who has been successfully resuscitated. From left to right: 2 control ECGs and 1, 2, 3, 4, and 5 minutes during IV infusion of 50 mg ajmaline. The ECG is “saddle back” type (type 2) in the left panels and becomes coved in the right panels (type 1). Calibrations are standard.Monitoring is recommended until the ECG has normalized (plasma half-life of flecainide is 20 hours, of procainamide is 3 to 4 hours, and ajmaline inactivated within a few minutes). Serious ventricular arrhythmias, including ventricular fibrillation (VF), may occur during the test. Immediate discontinuation of the drug is required, and isoproterenol infusion might be needed to treat the arrhythmias (1 to 3 μg/min isoproterenol14; P. Brugada, personal observations, 1999).It seems intuitive that the more sodium channel block is needed to elicit the Brugada phenotype, the less likely the patient is to be at risk under baseline conditions. Indeed, it was recently shown that asymptomatic patients with an abnormal ECG only on drug challenge have a benign prognosis.16 Canine ventricular wedge studies suggest that a flecainide-induced Brugada phenotype does not necessarily indicate the presence of an arrhythmic substrate; it does denote the ability of sodium channel block to create the conditions under which the arrhythmic substrate may readily develop.17Clinical PresentationAll too often, syncope or sudden cardiac death is the only symptom in patients with Brugada syndrome. In some cases, sudden death is the first symptom of the disease. Monitoring of such patients has revealed rapid polymorphic ventricular tachycardias (VTs) as the underlying cause. VT usually starts with a short coupling interval. Self-terminating episodes typically lead to repeated episodes of syncope. Indeed, 80% of patients with documented VF have a history of syncope.15 Clinical reports indicate that sudden death in patients with Brugada syndrome most commonly occurs during sleep, in particular during the early morning hours.9,18It has been suggested that there is a higher-than-normal incidence of supraventricular tachyarrhythmias, including atrial and atrioventricular reentrant tachycardia in the Brugada population.13 Rarely, monomorphic VT is observed.19,20 Family history is of paramount importance and is often positive for sudden cardiac death at a young age.The mean age at which symptoms first appear in affected individuals (males and females) is in the third to fourth decade. Among the first patients described, however, were symptomatic twins who were 1 year of age, and more recent reports describe families with symptomatic children.5,14 A patient in which first symptoms appeared at an age of 77 years has also been described.2Electrophysiological StudiesElectrophysiological studies (EPSs) may be helpful in risk stratification and in some cases in establishing the diagnosis. A complete EPS is recommended in all symptomatic patients. In VF survivors, EPS may be of little or no diagnostic value, but may be helpful in providing further insight into the predictive value of available diagnostic tools. In the absence of data on sensitivity or specificity of any EPS protocol, we suggest a protocol using 2 stimulation sites (right ventricular apex [RVA] and right ventricular outflow tract), at least 3 cycle lengths (600, 430, and 330 ms), 1, 2, and 3 extrastimuli, and a minimal coupling interval of 200 ms. At present, it is unknown whether shortening of the coupling interval to refractoriness, which might be very short in patients with Brugada syndrome, has additive value. Inducibility early in the protocol is common, but non-inducible cases have been described. About half of patients are inducible from the outflow tract. Isoproterenol does not enhance the likelihood of inducibility and in theory should have the opposite effect. The diagnostic value of repeating an EPS after class I drug treatment (or challenge) is not fully established. Similarly, the value of epicardial stimulation,21 as well as the value of right ventricular mapping with monophasic action potentials, is not known.22 Asymptomatic patients with a positive family history for SCD should be investigated in a similar way. The necessity for EPS is questionable in patients who display the Brugada ECG but who are asymptomatic and have a negative family history. In fact, accuracy to predict outcome is debated. Positive predictive value varies from 50%15 to 37%,23 and negative predictive value varies from 46%15 to 97%.16,23Differential DiagnosisThe list of factors contributing to ST-segment elevation is long (Table 2). Clinical diagnostic evaluation should be directed toward excluding each of these causes. Discrimination between Brugada syndrome and arrhythmogenic right ventricular cardiomyopathy (ARVC) may be particularly difficult because ARVC may at times mimic Brugada syndrome and structural abnormalities may only be found at time of autopsy.24,25 Before the diagnosis Brugada syndrome is made, a serious attempt should be taken to exclude ARVC. Drug challenge with sodium channel blockers may be useful in discriminating between these 2 diseases.7 Intuitively, one would expect a rightward shift of the ε wave, if present, in ARVC patients. Table 3 lists characteristics of the 2 diseases that may be useful in making a differential diagnosis. TABLE 2. Abnormalities That Can Lead to ST-Segment Elevation in the Right Precordial LeadsWhereas the last 2 “other conditions that can lead to ST-segment elevation” are more likely to give rise to type 2 and type 3 ECGs, most conditions mentioned in this table can give rise to type 1 ECG. Right or left bundle branch block, left ventricular hypertrophy28 Acute myocardial ischemia or infarction29 Acute myocarditis30 Right ventricular ischemia or infarction31 Dissecting aortic aneurysm32 Acute pulmonary thromboemboli33 Various central and autonomic nervous system abnormalities34,35 Heterocyclic antidepressant overdose36 Duche
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