The authors report the first catheter ablation of Brugada syndrome in the literature using the Rhythmia™ mapping system. Learning points include: (1) low voltage areas can be documented while mapping in some individuals, suggesting that Brugada syndrome may not be a pure ion channel disorder; (2) typical long fractionated potentials can also be identified in the endocardium, supporting the need to map the endocardium in all Brugada patients requiring ablation; (3) disappearance of the typical coved pattern following ablation does not necessarily predict cure, as the patient we present experienced ventricular fibrillation recurrence a few months later

Adragão, P

Carmo, P

Cavaco, D

Morgado, F

Moscoso Costa, F

Providência, R

Scanavacca, M

UCL Discovery

Brugada Syndrome Is Associated with Scar and Endocardial Involvement: Insights from High-Density Mapping with the RhythmiaTM Mapping System   Síndrome de Brugada Associado com Baixa Voltagem e Envolvimento Endocárdico: Achados de um Mapeamento de Alta Densidade com o Sistema RhythmiaTM Rui Providencia 1,2 MD PhD, Pedro Carmo 1 MD, Francisco Moscoso Costa 1 MD, Diogo Cavaco 1 MD, Francisco Morgado 1 MD, Mauricio Scanavacca 3 MD PhD, Pedro Adragao 1 MD PhD 1 Department of Cardiology, Santa Cruz Hospital, CHLO, Carnaxide, Portugal; 2 St. Bartholomew’s Hospital, Barts Health NHS Trust, London, United Kingdom, 3 Heart Institute (InCor), University of São Paulo Medical School Hospital, São Paulo, Brazil.  Images in Cardiology  Short title: Brugada Syndrome - Scar and endocardial involvement Word count: 491 *Corresponding author: Rui Providência Barts Heart Centre, Barts Health NHS Trust,  West Smithfield  London EC1A 7BE, United Kingdom e-mail: rui_providencia@yahoo.com Telephone number: +44 020 7377 7000 Fax: +44 020 7791 9670 Funding: none Disclosures and Conflicts of Interest –All authors have reported that they have no relationships relevant to the contents of this paper to disclose.  Abstract The authors report the first catheter ablation of Brugada syndrome in the literature using the Rhythmia-mapping system. Learning points include: 1. Low voltage areas can be documented while mapping in some these individuals, and suggesting that Brugada syndrome may not be a pure ion channel disorder. 2. Typical long-fractionated potentials can also be identified in the endocardium, supporting the need of mapping the endocardium in all Brugada patients requiring an ablation. 3. Disappearance of the typical coved-pattern following ablation does not necessarily predict cure as the case we presented still experienced ventricular fibrillation relapse a few months later. Key-words: Brugada syndrome; Channelopathies; Epicardial ablation; mapping systems; Rhythmia.   Resumo  Os autores descrevem a primeira ablação de Síndrome de Brugada usando o sistema de mapeamento Rhythmia. Pontos de aprendizagem incluem: 1. É possível observar fibrose ao mapear alguns destes indivíduos, sugerindo que a Síndrome de Brugada poderá não ser uma canalopatia pura. 2. Os potenciais fraccionados de longa duração também podem ser identificados no endocárdio, reforçando a necessidade de mapeamento também do endocárdio em todos os doentes com Brugada com indicação para ablação. 3. Desaparecimento do padrão típico “coved” não prevê necessariamente a cura uma vez que no caso apresentado uma recidiva de fibrilhação ventricular foi observada alguns meses mais tarde.  Key-words: Síndrome de Brugada; Canalopatias; Ablação epicárdica; Sistemas de Mapeamento; Rhythmia.   A 39 year-old male with Brugada syndrome (BS) and recurrent arrhythmia storms (nearly once a month) due to ventricular fibrillation (VF) resistant to maximum tolerated dose of quinidine was referred to catheter ablation in our Center. His heart was structurally normal, with normal left and right ventricular systolic function, no chamber dilation or ventricular wall motion abnormalities on recent echocardiogram assessment, and MRI performed years before. He had been implanted with an implantable cardioverter defibrillator following an out of hospital ventricular fibrillation episode. The patient presented with spontaneous type-1 pattern at the start of the procedure (Panel 1A), and both endocardial and epicardial access was obtained. The RhythmiaTM mapping system (Boston Scientific©, Massachusetts, USA) was used, and after mapping with the Intellamap OrionTM catheter (Boston Scientific©, Massachusetts, USA) fractionated potentials were targeted using the IntellanavTM Open-Irrigated catheter (Biosense Webster©, California, USA) (Panel 2). Some fractionated potentials were found in the right ventricular outflow tract (RVOT) endocardium (Panel 3), but longer potentials, measuring > 200 to 300ms, were observed mostly in the epicardial layer (Panel 4) (potential duration was measured from start to end of local EGM using the method described by Pappone et al. [1]). Interestingly, areas of scar were also detected in the right ventricular outflow tract endocardium and epicardium (Panels 2 and 3). Following ablation in the area (40W 30s per lesion until eradication of the long duration potentials), the coved type-1 pattern disappeared. After 9 months of follow-up, and no relapse of the coved-type 1 pattern (Panel 1B), the patient had a single episode of VF in the second month, and is now free from arrhythmia drugs. This first case BS ablation using the RhythmiaTM mapping system illustrates three important aspects: First, fibrosis can also present in some individuals with BS who do not meet criteria for arrhythmogenic right ventricular dysplasia. This fact had already been suggested by Coronel and colleagues [2]. Whether fibrosis results from a more aggressive channelopathy form where channel dysfunction leads to tissue changes, additional mutations or polymorphisms in different genes, or modulators leading to fibrosis, or fortuitous occurrence of localized myocarditis, remains to be explained. In this case no mutation or polymorphism could be identified, and therefore we cannot provide data to support the abovementioned hypothesis. However, a recent publication suggests that BS patients with SCN5A may exhibit more conduction abnormalities on ECG and have higher risk for cardiac events (Ref Yamagata et al). Nademanee and colleagues have shown increased collagen, fibrosis and reduced gap junction signalling protein Cx43 expression in the RVOT are present in BS patients [Nademanee et al 2015]. These data support the plausibility of BS reflecting a generalized disease of myocardial architecture, and the baseline properties of the RVOT which predispose it to fibrosis are likely to contribute to the condition and its arrhythmic risk. Presence of coexistent fibrosis may explain why up to 5% of patients BS may also develop monomorphic ventricular tachycardias [3]. Second, our findings of fractionated potentials in the endocardium (Panel 3) suggest there may still be a rational to chase ventricular ectopics originating from the area or ablating endocardial long-duration potentials [4]. In our case, as these potentials were only identified on retrospective analysis of the map and, therefore, not ablated, we cannot help but wonder if the preservation of this zone is the reason why the patient relapsed. A recent investigation using simultaneous non-invasive mapping of the endo and epicardium suggests that the both endo and epicardium appear to be involved in a substancial number of patients, and their interplay appears to play a role in the observed phenotype [Ref Documentation of abnormalities in endocardial and epicardial electrograms  Also, these are located in the low postero-septal region of the RVOT, which does not correspond to the traditional area of epicardial involvement in BS.  Third, disappearance of the coved-pattern does not necessarily predict cure. In this case we hypothesize that several factors may have contributed: a) existence of an underlying fibrotic substrate (which may have been aggravated with ablation); b) reduced transmyocardial repolarization gradient which was not enough to result in a coved type-1 pattern, but in the presence of an appropriately timed ventricular ectopic was still enough to degenerate into VF. Finally, much remains yet to be learned about BS, and the growing number of catheter ablations for this disease will surely help expand our knowledge. Using RhythmiaTM mapping system and taking advantage of its high-density mapping capabilities appears to be advantageous in this setting as very precise mapping, with no limit in the number of collected points, and identification of the culprit potentials is likely to have an impact on procedural success and prognosis of these patients. Furthermore, if the future of mapping in this condition is to follow the approach used by Pappone and colleagues, where repeated maps are performed following ablation and repeated ajmaline infusion, the ultra-rapid mapping potential of RhythmiaTM will make it a likely candidate for usage in this setting. The definition that can be obtained with high-density mapping contrasts with the resolution of point-by-point mapping using other mapping systems. For example, our epicardial map was composed of 50,472 electrograms, which is > 100 times more detailed to what has been described in a previous case report where only 304 points were collected [Ref Cortez Dias et al. 2012 Rev Port Cardiol].  In our case, we did not perform post-ablation ajmaline testing or programmed ventricular stimulation. The controversy regarding programmed ventricular stimulation has lasted for decades in the setting of risk assessment. Even though it has been used by authors [Ref Pappone e Cortez Dias] its role as a predictor of success of catheter ablation is still open to debate.   Acknowledgements: None    Figure Legend  Figure. Panel 1 Pre-cordial leads (V1 to V3) showing presence of spontaneous type-1 Brugada pattern at the start of the procedure, and its disappearance 9 months after; Panel 2 – Epicardial voltage map of the right ventricle using RhythmiaTM mapping system, AP view, with 0.5 and 1.5mV as voltage cut-off points showing wide areas of fibrosis in the RVOT and anterior wall of the right ventricle. Panel 3 – Endocardial voltage map of the right ventricle, PA view, showing an area of fibrosis in the postero-septal aspect of the RVOT. A long (>120ms), complex, small amplitude and fractionated potential is highlighted. Panel 4 – Potential duration map of the epicardial aspect of the right ventricle, AP view, showing area of potentials lasting longer than 291ms (purple), corresponding to the ablated zone. Areas of potentials lasting less than 200ms are coloured in red. Highlighted is a very long and complex potential measuring approximately 371ms. Legend: PA – pulmonary artery; TV – tricuspid valve.     References  1. Pappone C, Brugada J, Vicedomini G, et al. Epicardial ablation in Brugada syndrome. Insights from a prospective registry study of 50 consecutive patients. Europace 2016;18(suppl_1):i25. 2. Coronel R, Casini S, Koopmann TT, et al. Right ventricular fibrosis and conduction delay in a patient with clinical signs of Brugada syndrome. A combined electrophysiological, genetic, histopathologic, and computational study. Circulation 2005;112:2769-2777. 3. Rodríguez-Mañero M, Sacher F, de Asmundis C, et al. Monomorphic ventricular tachycardia in patients with Brugada syndrome: A multicentre retrospective study. Heart Rhythm 2016;13:683-5. 4. Haïssaguerre M, Extramiana F, Hocini M, et al. Mapping and ablation of ventricular fibrillation associated with long-QT and Brugada syndromes. Circulation 2003;108:925-928. 

Brugada syndrome is associated with scar and endocardial involvement: Insights from high-density mapping with the Rhythmia™ mapping system

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Brugada syndrome is associated with scar and endocardial involvement: Insights from high-density mapping with the Rhythmia™ mapping system

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