Response to Letter Regarding Article, “High-Density Substrate Mapping in Brugada Syndrome: Combined Role of Conduction and Repolarization Heterogeneities in Arrhythmogenesis”

Lambiase, Pier D.; Ahmed, Ayesha; Ben-Simon, Ron; Chow, Anthony W.; McKenna, William J.; Ciaccio, Edward J.; Brugada, R.; Lizotte, Éric; Chaubey,

doi:10.1161/cir.0b013e3181d8d4b5

Cited by 53 publications

(77 citation statements)

References 4 publications

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“…63 Moderate conduction abnormalities were found in Brugada syndrome patients in right ventricular endocardial stimulation and mapping studies. 64,65 Unipolar electrograms of Brugada syndrome patients contained more fractionation 65 and more right ventricular activation delay after shortly coupled premature stimuli than of control patients. 64,65 Activation delay on shortly coupled premature stimuli has been demonstrated to depend on the arrangement of structural discontinuities in the myocardium.…”

Section: Electrophysiologic Studiesmentioning

confidence: 88%

“…64,65 Unipolar electrograms of Brugada syndrome patients contained more fractionation 65 and more right ventricular activation delay after shortly coupled premature stimuli than of control patients. 64,65 Activation delay on shortly coupled premature stimuli has been demonstrated to depend on the arrangement of structural discontinuities in the myocardium. 66 The Brugada ECG pattern can also be provoked in patients with cardiac conditions characterized by overt structural abnormalities.…”

Section: Electrophysiologic Studiesmentioning

confidence: 88%

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The Brugada ECG Pattern

Hoogendijk

Opthof

Postema

et al. 2010

Circ: Arrhythmia and Electrophysiology

128

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I n 1992, Brugada and Brugada introduced a new clinical entity characterized by right precordial ST-segment elevation followed by a negative T-wave and a high incidence of ventricular fibrillation (VF) in the absence of structural heart disease. 1 The typical ECG anomaly is currently known as the Brugada ECG pattern and the conglomerate of features as the Brugada syndrome. Over the years, the Brugada syndrome has been recognized as an important cause of sudden cardiac death in young men, especially in Southeast Asia, 2 and has attracted much attention from researchers and clinicians alike. This has led to substantial progress in identification of modulating factors of the Brugada ECG pattern, the associated ventricular arrhythmias, and in the risk stratification of patients. 3 However, the development of effective therapeutic strategies has lagged behind. Currently, symptomatic treatment with implantable cardioverterdefibrillators (ICDs) is the mainstay in the prevention of sudden cardiac death, 3 although it is costly and associated with a high risk of complications. 4 The pathophysiological mechanism of the Brugada syndrome remains elusive, 5 and no single causal factor appears to link all patients. The Brugada ECG pattern is modulated by genetic mutations and pharmacological agents that alter the function of ion channels active during the early phases of the action potential. Furthermore, signs of right ventricular structural abnormalities are often found in patients with Brugada syndrome. The aim of this study is to review the available literature on the Brugada syndrome in an attempt to provide a unifying hypothesis of the mechanism of the Brugada syndrome. This unifying hypothesis should be able to explain the ECG pattern, the arrhythmogenic mechanism, their modulation by ion channels, and the relation of structural abnormalities to the Brugada syndrome. Is the Brugada Syndrome a Channelopathy?The Brugada syndrome was introduced shortly after the first demonstration of statistical linkage between the long-QT syndrome (LQTS) and a gene locus. 6 Since then, genetic mutations that alter ion channel functions and prolong the QT duration were linked with the LQTS. 7 These observations defined the LQTS as a channelopathy. In analogy with the LQTS, a hereditary pattern was suspected in half the Brugada syndrome cases. Additionally, no structural heart disease was demonstrated, suggesting that the Brugada syndrome also was a channelopathy. 1 Over the years, this analogy was substantiated by further observations of similarity with the LQTS. GeneticsGenetic mutations that alter ion channel functions have been identified in patients with Brugada syndrome. The first identified mutations were located in SCN5A, the gene encoding the ␣-subunit of the cardiac sodium channel, leading to reduced cardiac sodium current (I Na ). 8 The prevalence of SCN5A mutations is Ϸ20% 9 and is higher in patients with than without a family history of Brugada syndrome. 10 Recently, mutations in GPD1L 11 , a gene probably involved in the tra...

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Section: Electrophysiologic Studiesmentioning

confidence: 88%

Section: Electrophysiologic Studiesmentioning

confidence: 88%

The Brugada ECG Pattern

Hoogendijk

Opthof

Postema

et al. 2010

Circ: Arrhythmia and Electrophysiology

128

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“…11) Furthermore, previous studies revealed that marked regional endocardial conduction delay and heterogeneities in repolarization exist in Brugada syndrome, and wave break in areas of maximal conduction delay appears to be critical in the initiation and maintenance of VT. 12) These findings indicate that further mapping studies to identify slow conduction zones should be considered to determine the role of these zones in spontaneous ventricular arrhythmias. Nagase, et al reported that delayed potentials could be recorded from epicardial electrograms in patients with Brugada syndrome.…”

Section: Discussionmentioning

confidence: 95%

“…5,6) However, recent studies suggested that conduction delay in the right ventricle is related to arrhythmias associated with Brugada syndrome (depolarization disorder). [7][8][9][10][11][12][13][14][15] Furthermore, structural abnormalities in the right ventricle are reported in Brugada syndrome. [16][17][18] We conducted a single-center case-control electroanatomic mapping study in patients with and without Brugada syndrome to identify the arrhythmogenic substrates in Brugada syndrome.…”

mentioning

confidence: 99%

Clarifying the Arrhythmogenic Substrate for Brugada Syndrome Electroanatomic Mapping Study of the Right Ventricle

et al. 2011

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SummaryThe right ventricular outflow tract (RVOT) is considered the arrhythmogenic region that gives rise to Brugada syndrome. To obtain a better understanding of this substrate, we performed electroanatomic mapping of the right ventricle (RV) in patients with Brugada syndrome.The RV was mapped electroanatomically with the CARTO system in 11 patients with asymptomatic Brugada syndrome but in whom ventricular fibrillation was induced by programmed ventricular stimulation, and in 5 control patients. The low voltage zone area (< 1.5 mV) was larger (16.1% versus 7.8%, P < 0.01) and the bipolar electrogram duration was greater (81.6 ± 7.8 ms versus 53.4 ± 5.6 ms, P < 0.01) in the patients with Brugada syndrome versus the control patients; the bipolar electrogram duration was greater in the septal portion and free wall of the RVOT.Our data suggest that regional endocardial conduction slowing based on structural abnormalities exists at the RVOT in Brugada syndrome. (Int Heart J 2011; 52: 290-294)

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“…1 Complex and interesting electrophysiological data are presented, giving new insights into Brugada syndrome features. However, we feel that some methodological flaws in patient characterization, mapping procedure, and data interpretation give different perspectives to their conclusions.…”

Section: To the Editormentioning

confidence: 99%