Arq Bras Cardiol Arquivos Brasileiros de Cardiologia Arq. Bras. Cardiol. 0066-782X 1678-4170 Sociedade Brasileira de Cardiologia ZkBHLYP5hmGgcsxmj5VzTfK S0066-782X2014000600001 00001 10.5935/abc.20140082 Editorial Epicardial Ablation for Ventricular Tachycardia in Chronic Chagas Heart Disease Scanavacca Mauricio FMUSP HC Instituto do Coração São Paulo SP Brazil Instituto do Coração (InCor) -HC-FMUSP. São Paulo, SP - Brazil Mailing address: Mauricio Scanavacca. Av. Joaquim C. A. Marques, 1.205. Postal Code 05688-021, Morumbi, SP - Brazil. Email: mauricio.scanavacca@gmail.com 06 2014 102 6 524 528 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Chagas Cardiomyopathy Tachycardia, ventricular Catheter ablation

The Chagas Heart Disease, described for the first time in 1909 by Carlos Chagas, is caused by Trypanosoma cruzi, a flagellated protozoa transmitted to humans, mostly by the feces of Triatoma infestans in endemic areas. Estimates are that fifteen million people are infected in Latin America, leading to 45,000 deaths per year, 90% owing to heart disease.

The cardiac involvement is the most prevalent and severe manifestation of Chagas Heart Disease. After the infection, most individuals remain without manifestation of the disease along their lives, but at least 30% develop heart rhythm disorders, severe symptoms of heart failure and thromboembolic events, typically after 10-30 years after infection. Chronic myocarditis predisposes to cardiac dilation and to the formation of ventricular aneurysms. Thrombi are more prevalent in apical ventricular aneurysm, which is typical of the disease, and the cause for thromboembolic events in the systemic and pulmonary circulation. Segmental myocardial fibrosis is the anatomical substrate for ventricular arrhythmias and atrio-ventricular and intraventricular conduction abnormalities. Sudden death occurs in 55-65% of the patients, at times in the absence of prior cardiac symptoms. Death as a result of heart failure happens in 25-30%, and cerebral or pulmonary embolism, in 10-15%1-3.

Ventricular extrasystoles are rather common in patients with Chagas Heart Disease, and its prevalence and complexity are associated with the extent of myocardial injury, particularly with left ventricular dysfunction and dilation4. Non-sustained ventricular tachycardia (NSVT) has been recognized as an independent risk factor for death and included in score for risk stratification5. Sustained ventricular tachycardia (SVT) is considered the main cause of sudden death, and may happen in different stages of the disease and even in patients without important ventricular dysfunction6.

Amiodarona is the most commonly used antiarrhythmic drug in Brazil to treat ventricular arrhythmias in patients with Chagas Heart Disease. Cohort studies involving patients with sustained Chagas Heart Disease and VT revealed 5-11.9% of annual mortality, with sudden death representing 61-78% of the cases, mostly with important ventricular systolic dysfunction7-10. On account of this, the implantable cardioverter defibrillator (ICD) has been recommended to patients with sustained VT and ventricular dysfunction11-14. However, patients with Chagas Heart Disease seem to receive more ICD shocks compared to patients with coronary heart disease. A relevant finding was the annual mortality of 16.6% in a cohort of 90 patients with Chagas Heart Disease subject to ICD implantation due to sustained VT. Although the patients presented low rate of sudden death, they had a significant rate of total mortality. Patients with more than four shocks over a period of 30 days presented higher mortality compared to patients with no shock or a smaller number11. Since these patients mostly died from heart failure, one can speculate that excessive shocks applied by ICD may depress the ventricular function and increase non-sudden mortality. This data corroborate the indication of catheter ablation as the logical strategy to reduce the recurrence of sustained VT and prevent ICD shocks15.

Catheter Ablation of Sustained VT in Chagas Heart Disease

The main mechanism of SVT of chronic Chagas Heart Disease is the reentry located in a left ventricle inferolateral and baseline scar in more than 70% of the cases16,17. The reentrant circuit of SVT may involve subendocardial, intramyocardial and subepicardial fibers. In some patients, the reentrant circuits have their genesis in places with very thin walls and, on account of that, conventional pulses of RF, emitted from the endocardium, may cause transmural injury and reach all the structures potentially involved in the circuit. Nevertheless, in others, the segmental injury is intramural and the circuit is predominantly kept by subepicardial fibers. Insofar as the contralateral subendocardial tissue is very thick, it may prevent RF applications from reaching the causative intramyocardial and subepicardial fibers and be the reason for an unsuccessful procedure. This was the initial hypothesis for resorting to the transthoracic subxiphoid percutaneous approach to explore the pericardial space and identify patients with possible subepicardial circuits15.

 Epicardial Ablation of Sustained VT in Chagas Heart Disease

The transthoracic epicardial approach has been used since 1995 for mapping and ablation of sustained VT in patients with Chagas Heart Disease18 and subsequently also applied in patients with other heart diseases19. The experience acquired over time confirmed the initial findings20-23, and consensus documents issued by different medical societies report that it is necessary in at least 20% of the patients subject of SVT ablation in tertiary centers, mainly in patients with non-ischemic heart diseases24,25. Recent review underscores the current importance of the subxiphoid percutaneous approach in several intrapericardial procedures26.

The technique of access to the periocardial space has been kept virtually unchanged over time, with nearly no technological advance for its performance27. The Tuohy needle is the main tool to reach the pericardial space (Figure 1). It is curved at one end, which makes it easier to penetrate pericardial membranes (Figure 2). A risk of 10% of pericardial bleeding is forecasted when applying this technique, usually a minor and transient one. The risk of severe bleeding demanding surgical repair is around 1-2%. In most patients subject to this approach, the epicardial mapping widens the exploration area. Pericardial adhesions are not common after prior ablations either.

Access to the normal pericardial space for epicardial mapping and ablation by subxiphoid puncture. In detail, the Tuhoy needle drawn for epidural anesthesia and used in this procedure to mitigate the risk of cardiac perforation. Technique of access to the normal pericardial space. A: Subxiphoid puncture with Tuhoy needle. The epigastric compression makes it easier to introduce the needle in the pericardial space, lowering the risk of intra-abdominal organ perforation, mainly the liver. B: Heart fluoroscopy in left anterior oblique projection (LAO) showing the right positioning of the guide wire in the pericardial space. C, D, E: Fluoroscopic aspects in right anterior oblique (RAO) and LAO of the positioning of the exploratory catheter on the heart epicardial surface.

The electrophysiological signs obtained during the epicardial mapping show patterns similar to those obtained with the endocardial mapping, whether in patients with Chagas Heart Disease or with other heart diseases. Delayed potentials are most predominantly found in the target area during mapping in sinus rhythm and pre-systolic activity. Meso-diastolic and continuous activities are also frequent in the original place of VT. The critical isthmus of the reentrant circuit in the subepicardial tissue may be confirmed by entrainment maneuvers or interruption of VT during the application of RF in these places, as can be observed by the endocardial approach. The prevalence of epicardial VT in 257 consecutive patients was higher in patients with Chagas Heart Disease (37%) compared to patients after myocardial infarction (28%) and patients with idiopathic dilated cardiomyopathy (24%)28.

Three anatomical aspects of the epicardial surface may hamper the efficiency of epicardial ablation: the presence of epicardial coronary artery, a thick layer of fat and the risk of causing injury in neighboring tissues, such as the phrenic nerve29. For all these reasons and more, a substantial number of patients still present clinical recurrences after endocardial and epicardial ablation, whether due to limitations found during the procedure or to the evolution of the disease. The recurrence rate seems to decrease after the introduction of electroanatomic mapping to establish the scar extension and limits (Figures 3 and 4), and irrigated-tip catheter ablations (deeper injuries, even in the presence of fat) may bring on wider substrate injuries30. Alternatively, wider epicardial injuries may increase the risk of damaging the coronary arteries and extracardiac structures31,32.

Electroanatomic mapping in patients with Sustained Ventricular Tachycardia (SVT) secondary to Chronic Chagas’ Cardiomyopathy (CCC). A: ECG in sinus rhythm. Note that there are no disturbances of the atrioventricular and intraventricular conduction or electrically inactive areas, but only change of repolarization of the left ventricle (LV) inferior and lateral walls, secondary to the segmental scar located in the same regions (panels C and D). B: ECG of SVT with electrocardiographic pattern suggesting origin in the LV baseline region (positive QRS of V1 to V6), with onset of ventricular activation on the lateral wall (negative QRS in DI and aVL and positive in D2, D3 and aVF). C: 3D electroanatomic mapping of the LV endocardial and epicardial surfaces in sinus rhythm with the Carto system. The colors represent the amplitude of the ventricular electrograms in the investigated regions. Note that the low-voltage area, suggesting the presence of scar, is predominantly epicardial. D: Integration of the endocardium and epicardium maps showing the LV inferior lateral and baseline segmental injury, anatomical substrate for SVT in this patient. SVT ablation in the same patient of <xref ref-type="fig" rid="f03">Figure 3</xref>. A: Electrophysiological scan documenting the moment of application of RF pulse by epicardial catheter with interrupts SVT and restores the sinus rhythm. I, II, III, V1 and V6: ECG leads synchronized with intracavitary electrograms. RV p and RV d: bipolar electrograms obtained by proximal and distal electrode placements of the right ventricle, respectively. LV epi p and LV epi d: bipolar electrograms obtained, respectively, by proximal and distal electrodes of the epicardial catheter positioned on the LV inferior and lateral scar. VE endo p: bipolar sign of the catheter introduced in the LV. RF: moment of application of radio frequency power, which interrupts SVT. The application is kept by 60 seconds. Speed of registration: 25 mm/s. B: Posterior view of the voltage electroanatomic map showing the limits of LV inferior, lateral and baseline scar. The purple and pink spots indicate places with fractionated and delayed electrograms during the sinus rhythm. The green spots indicate the transition between the left ventricle and left atrium. C: Same electroanatomic mapping view showing the RF applications (red spots) in the SVT origin site.

Prospective randomized study is required to evaluate the role and risks of different strategies during catheter ablations in patients with Chagas Heart Disease33-38. However, there is a special group of patients to whom catheter ablation presents arguable benefits: patients with ICD receiving multiple shocks, regardless of the adjuvant therapy with antiarrhythmic drugs. In these cases, the clinical outcomes are very clear in short and medium-term evaluations39. It is worth noting that the Chagas Heart Disease has a progressive nature, and it is not uncommon for patients with good left ventricular function to have favorable SVT ablations, but return 5-10 years afterwards presenting left ventricular dysfunction and recurrence of new SVT.

 References 1. Andrade JP, Marin-Neto JA, Paola AA, et al. I Latin American guidelines for the diagnosis and treatment of Chagas cardiomyopathy. Arq Bras Cardiol. 2011;97(2 Suppl 3):1-48 Andrade JP Marin-Neto JA Paola AA et al I Latin American guidelines for the diagnosis and treatment of Chagas cardiomyopathy Arq Bras Cardiol 2011 97 2 Suppl 3 1 48 2. Pinto Dias JC. Natural history of Chagas disease. Arq Bras Cardiol. 1995;65(4):359-66. Pinto Dias JC Natural history of Chagas disease Arq Bras Cardiol 1995 65 4 359 366 3. Rassi Jr A, Rassi A, Marin-Neto JA. Chagas disease. Lancet 2010; 375:1388-402. Rassi A Jr Rassi A Marin-Neto JA Chagas disease Lancet 2010 375 1388 1402 4. Barretto AC, Mady C, Ianni BM, Arteaga E, Cardoso RH, da Luz PL, Pileggi F. Relationship between ventricular arrhythmia and cardiac function in Chagas disease. Arq Bras Cardiol. 1995;64(6):533-5. Barretto AC Mady C Ianni BM Arteaga E Cardoso RH da Luz PL Pileggi F Relationship between ventricular arrhythmia and cardiac function in Chagas disease Arq Bras Cardiol 1995 64 6 533 535 5. Rassi A Jr, Rassi A, Little WC, et al. Development and validation of a risk score for predicting death in Chagas' heart disease. N Engl J Med 2006;355:799-808. Rassi A Jr Rassi A Little WC et al Development and validation of a risk score for predicting death in Chagas' heart disease N Engl J Med 2006 355 799 808 6. Sternick EB, Martinelli M, Sampaio R, Gerken LM, Teixeira RA, Scarpelli R, Scanavacca M, Nishioka SD, Sosa E. Sudden cardiac death in patients with Chagas heart disease and preserved left ventricular function. J Cardiovasc Electrophysiol. 2006;17(1):113-6. Sternick EB Martinelli M Sampaio R Gerken LM Teixeira RA Scarpelli R Scanavacca M Nishioka SD Sosa E Sudden cardiac death in patients with Chagas heart disease and preserved left ventricular function J Cardiovasc Electrophysiol 2006 17 1 113 116 7. Scanavacca MI, Sosa EA, Lee JH, et al. Empiric therapy with amiodarona in patients with chronic Chagas cardiomyopathy and sustained ventricular tachycardia. Arq Bras Cardiol 1990;54(6):367-71. Scanavacca MI Sosa EA Lee JH et al Empiric therapy with amiodarona in patients with chronic Chagas cardiomyopathy and sustained ventricular tachycardia Arq Bras Cardiol 1990 54 6 367 371 8. Leite LR, Fenelon G, Simões JR, et al. Clinical usefulness of electrophysiology testing in patients with ventricular tachycardia and chronic chagasic cardiomyopathy treated with amiodarona or sotalol. J Cardiovasc Electrophysiol 2003;14:567-73. Leite LR Fenelon G Simões JR et al Clinical usefulness of electrophysiology testing in patients with ventricular tachycardia and chronic chagasic cardiomyopathy treated with amiodarona or sotalol J Cardiovasc Electrophysiol 2003 14 567 573 9. Sarabanda AV, Marin-Neto JA. Predictors of mortality in patients with Chagas' cardiomyopathy and ventricular tachycardia not treated with implantable cardioverter-defibrillators. Pace 2011;34(1):54-62. Sarabanda AV Marin-Neto JA Predictors of mortality in patients with Chagas' cardiomyopathy and ventricular tachycardia not treated with implantable cardioverter-defibrillators Pace 2011 34 1 54 62 10. Rassi A Jr. Implantable cardioverter-defibrillators in patients with Chagas heart disease: misperceptions, many questions and the urgent need for a randomized clinical trial. J Cardiovasc Electrophysiol 2007;18(12):1241-3. Rassi A Jr Implantable cardioverter-defibrillators in patients with Chagas heart disease: misperceptions, many questions and the urgent need for a randomized clinical trial J Cardiovasc Electrophysiol 2007 18 12 1241 1243 11. Cardinalli-Neto A, Bestetti RB, Cordeiro JA, et al. Predictors of all-cause mortality for patients with chronic Chagas' heart disease receiving implantable cardioverter defibrillator therapy. J Cardiovasc Electrophysiol 2007;18(12):1236-40. Cardinalli-Neto A Bestetti RB Cordeiro JA et al Predictors of all-cause mortality for patients with chronic Chagas' heart disease receiving implantable cardioverter defibrillator therapy J Cardiovasc Electrophysiol 2007 18 12 1236 1240 12. Martinelli M, de Siqueira SF, Sternick EB, Rassi A Jr, Costa R, Ramires JA, Kalil Filho R. Long-term follow-up of implantable cardioverter-defibrillator for secondary prevention in chagas' heart disease Am J Cardiol. 2012;110(7):1040-5. Martinelli M de Siqueira SF Sternick EB Rassi A Jr Costa R Ramires JA Kalil R Filho Long-term follow-up of implantable cardioverter-defibrillator for secondary prevention in chagas' heart disease Am J Cardiol 2012 110 7 1040 1045 13. Barbosa MP, Rocha MO, Lombardi F, Ribeiro AL. ICDs in Chagas heart disease: the standard treatment for secondary prevention of sudden deathEuropace. 2013;15(9):1383-4. Barbosa MP Rocha MO Lombardi F Ribeiro AL ICDs in Chagas heart disease: the standard treatment for secondary prevention of sudden death Europace 2013 15 9 1383 1384 14. Gali WL, Sarabanda AV, Baggio JM, Ferreira LG, Gomes GG, Marin-Neto JA, Junqueira LF.Implantable cardioverter-defibrillators for treatment of sustained ventricular arrhythmias in patients with Chagas' heart disease: comparison with a control group treated with amiodarone alone. Europace. 2014;16(5):674-80. Gali WL Sarabanda AV Baggio JM Ferreira LG Gomes GG Marin-Neto JA Junqueira LF Implantable cardioverter-defibrillators for treatment of sustained ventricular arrhythmias in patients with Chagas' heart disease: comparison with a control group treated with amiodarone alone Europace 2014 16 5 674 680 15. Scanavacca MI, de Brito FS, Maia I, et al. Brasileira de Cardiologia S. Guidelines for the evaluation and treatment of patients with cardiac arrhythmias. Arq Bras Cardiol 2002;79(Suppl 5):1-50. Scanavacca MI de Brito FS Maia I et al Brasileira de Cardiologia S Guidelines for the evaluation and treatment of patients with cardiac arrhythmias Arq Bras Cardiol 2002 79 Suppl 5 1 50 16. Sarabanda AV, Sosa E, Simões MV, et al. Ventricular tachycardia in Chagas' disease: a comparison of clinical, angiographic, electrophysiologic and myocardial perfusion disturbances between patients presenting with either sustained or nonsustained forms. Int J Cardiol 2005;102(1):9-19. Sarabanda AV Sosa E Simões MV et al Ventricular tachycardia in Chagas' disease: a comparison of clinical, angiographic, electrophysiologic and myocardial perfusion disturbances between patients presenting with either sustained or nonsustained forms Int J Cardiol 2005 102 1 9 19 17. de Mello RP, Szarf G, Schvartzman PR, Nakano EM, Espinosa MM, Szejnfeld D, Fernandes V, Lima JA, Cirenza C, De Paola AA. Delayed enhancement cardiac magnetic resonance imaging can identify the risk for ventricular tachycardia in chronic Chagas' heart disease. Arq Bras Cardiol. 2012;98(5):421-30. de Mello RP Szarf G Schvartzman PR Nakano EM Espinosa MM Szejnfeld D Fernandes V Lima JA Cirenza C De Paola AA Delayed enhancement cardiac magnetic resonance imaging can identify the risk for ventricular tachycardia in chronic Chagas' heart disease Arq Bras Cardiol 2012 98 5 421 430 18. Sosa E, Scanavacca M, d'Avila A, et al. A new technique to perform epicardial mapping in the electrophysiology laboratory. J Cardiovasc Electrophysiol 1996;7(6):531-6. Sosa E Scanavacca M d'Avila A et al A new technique to perform epicardial mapping in the electrophysiology laboratory J Cardiovasc Electrophysiol 1996 7 6 531 536 19. Sosa E, Scanavacca M, D'Avila A, et al. Radiofrequency catheter ablation of ventricular tachycardia guided by nonsurgical epicardial mapping in chronic chagasic heart disease. Pacing Clin Electrophysiol 1999;22:128-30. Sosa E Scanavacca M D'Avila A et al Radiofrequency catheter ablation of ventricular tachycardia guided by nonsurgical epicardial mapping in chronic chagasic heart disease Pacing Clin Electrophysiol 1999 22 128 130 20. Sosa E, Scanavacca M, d'Avila A, Oliveira F, Ramires JA. Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction. J Am Coll Cardiol. 2000;35:1442-1449. Sosa E Scanavacca M d'Avila A Oliveira F Ramires JA Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction J Am Coll Cardiol 2000 35 1442 1449 21. Sacher F, Roberts-Thomson K, Maury P, Tedrow U, Nault I, Steven D, Hocini M, Koplan B, Leroux L, Derval N, Seiler J, Wright MJ, Epstein L, Haissaguerre M, Jais P, Stevenson WG. Epicardial ventricular tachycardia ablation a multicenter safety study. J Am Coll Cardiol. 2010;55:2366-2372. Sacher F Roberts-Thomson K Maury P Tedrow U Nault I Steven D Hocini M Koplan B Leroux L Derval N Seiler J Wright MJ Epstein L Haissaguerre M Jais P Stevenson WG Epicardial ventricular tachycardia ablation a multicenter safety study J Am Coll Cardiol 2010 55 2366 2372 22. Della Bella P, Brugada J, Zeppenfeld K, Merino J, Neuzil P, Maury P, Maccabelli G, Vergara P, Baratto F, Berruezo A, Wijnmaalen AP. Epicardial ablation for ventricular tachycardia: a European multicenter study. Circ Arrhythm Electrophysiol. 2011;4:653-659. Della Bella P Brugada J Zeppenfeld K Merino J Neuzil P Maury P Maccabelli G Vergara P Baratto F Berruezo A Wijnmaalen AP Epicardial ablation for ventricular tachycardia: a European multicenter study Circ Arrhythm Electrophysiol 2011 4 653 659 23. Fox MC, Lakdawala N, Miller AL, Loscalzo J. Clinical problem-solving. A patient with syncope.N Engl J Med. 2013;369(10):966-72. Fox MC Lakdawala N Miller AL Loscalzo J Clinical problem-solving. A patient with syncope N Engl J Med 2013 369 10 966 972 24. Natale A, Raviele A, Al-Ahmad A, Alfieri O, Aliot E, Almendral J, Breithardt G, Brugada J, Calkins H, Callans D, Cappato R, Camm JA, Della Bella P, Guiraudon GM, Haïssaguerre M, Hindricks G, Ho SY, Kuck KH, Marchlinski F, Packer DL, Prystowsky EN, Reddy VY, Ruskin JN, Scanavacca M, Shivkumar K, Soejima K, Stevenson WJ, Themistoclakis S, Verma A, Wilber D; Venice Chart members. Venice Chart International Consensus document on ventricular tachycardia/ventricular fibrillation ablation. J Cardiovasc Electrophysiol. 2010;21(3):339-79. Natale A Raviele A Al-Ahmad A Alfieri O Aliot E Almendral J Breithardt G Brugada J Calkins H Callans D Cappato R Camm JA Della Bella P Guiraudon GM Haïssaguerre M Hindricks G Ho SY Kuck KH Marchlinski F Packer DL Prystowsky EN Reddy VY Ruskin JN Scanavacca M Shivkumar K Soejima K Stevenson WJ Themistoclakis S Verma A Wilber D Venice Chart members Venice Chart International Consensus document on ventricular tachycardia/ventricular fibrillation ablation J Cardiovasc Electrophysiol 2010 21 3 339 379 25. Aliot EM, Stevenson WG, Almendral-Garrote JM, Bogun F, Calkins CH, Delacretaz E, Bella PD, Hindricks G, Jais P, Josephson ME, Kautzner J, Kay GN, Kuck KH, Lerman BB, Marchlinski F, Reddy V, Schalij MJ, Schilling R, Soejima K, Wilber D. EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias: developed in a partnership with the European Heart Rhythm Association (EHRA), a Registered Branch of the European Society of Cardiology (ESC), and the Heart Rhythm Society (HRS); in collaboration with the American College of Cardiology (ACC) and the American Heart Association (AHA). Europace. 2009;11:771-817. Aliot EM Stevenson WG Almendral-Garrote JM Bogun F Calkins CH Delacretaz E Bella PD Hindricks G Jais P Josephson ME Kautzner J Kay GN Kuck KH Lerman BB Marchlinski F Reddy V Schalij MJ Schilling R Soejima K Wilber D EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias: developed in a partnership with the European Heart Rhythm Association (EHRA), a Registered Branch of the European Society of Cardiology (ESC), and the Heart Rhythm Society (HRS); in collaboration with the American College of Cardiology (ACC) and the American Heart Association (AHA) Europace 2009 11 771 817 26. Boyle NG, Shivkumar K. Epicardial interventions in electrophysiology. Circulation. 2012;126(14):1752-69. Boyle NG Shivkumar K Epicardial interventions in electrophysiology Circulation 2012 126 14 1752 1769 27. Pisani CF, Lara S, Scanavacca M. Epicardial ablation for cardiac arrhythmias: techniques, indications and results. Curr Opin Cardiol. 2014;29(1):59-67. Pisani CF Lara S Scanavacca M Epicardial ablation for cardiac arrhythmias: techniques, indications and results Curr Opin Cardiol 2014 29 1 59 67 28. Scanavacca M, Sosa E. Epicardial Ablation of Ventricular Tachycardia in Chagas Heart Disease. In: Shivkumar K, Boyle NG, eds. Cardiac Electrophysiology Clinics: Epicardial Interventions in Electrophysiology. Vol 2. Philadelphia, PA: Saunders; 2010:55-67. Scanavacca M Sosa E Epicardial Ablation of Ventricular Tachycardia in Chagas Heart Disease Shivkumar K Boyle NG Cardiac Electrophysiology Clinics: Epicardial Interventions in Electrophysiology Vol 2 Philadelphia, PA Saunders 2010 55 67 29. D'Avila A, Scanavacca M, Sosa E, Ruskin JN, Reddy VY. Pericardial anatomy for the interventional electrophysiologist. J Cardiovasc Electrophysiol. 2003;14:422-430. D'Avila A Scanavacca M Sosa E Ruskin JN Reddy VY Pericardial anatomy for the interventional electrophysiologist J Cardiovasc Electrophysiol 2003 14 422 430 30. Valdigem BP, da Silva NJ, Dietrich CO, Moreira D, Sasdelli R, Pinto IM, Cirenza C, de Paola AA. Accuracy of epicardial electroanatomic mapping and ablation of sustained ventricular tachycardia merged with heart CT scan in chronic Chagasic cardiomyopathy. J Interv Card Electrophysiol. 2010;29(2):119-25. Valdigem BP da Silva NJ Dietrich CO Moreira D Sasdelli R Pinto IM Cirenza C de Paola AA Accuracy of epicardial electroanatomic mapping and ablation of sustained ventricular tachycardia merged with heart CT scan in chronic Chagasic cardiomyopathy J Interv Card Electrophysiol 2010 29 2 119 125 31. Viles-Gonzalez JF, de Castro Miranda R, Scanavacca M, Sosa E, d'Avila A. Acute and chronic effects of epicardial radiofrequency applications delivered on epicardial coronary arteries.Circ Arrhythm Electrophysiol. 2011;4:526-31. Viles-Gonzalez JF de Castro Miranda R Scanavacca M Sosa E d'Avila A Acute and chronic effects of epicardial radiofrequency applications delivered on epicardial coronary arteries Circ Arrhythm Electrophysiol 2011 4 526 531 32. Koruth JS, Aryana A, Dukkipati SR, Pak HN, Kim YH, Sosa EA, Scanavacca M, Mahapatra S, Ailawadi G, Reddy VY, d'Avila A. Unusual complications of percutaneous epicardial access and epicardial mapping and ablation of cardiac arrhythmias. Circ Arrhythm Electrophysiol. 2011;4:882-888. Koruth JS Aryana A Dukkipati SR Pak HN Kim YH Sosa EA Scanavacca M Mahapatra S Ailawadi G Reddy VY d'Avila A Unusual complications of percutaneous epicardial access and epicardial mapping and ablation of cardiac arrhythmias Circ Arrhythm Electrophysiol 2011 4 882 888 33. Reddy VY, Reynolds MR, Neuzil P, Richardson AW, Taborsky M, Jongnarangsin K, Kralovec S, Sediva L, Ruskin JN, Josephson ME: Prophylactic catheter ablation for the prevention of defibrillator therapy. N Engl J Med 2007;357:2657-2665. Reddy VY Reynolds MR Neuzil P Richardson AW Taborsky M Jongnarangsin K Kralovec S Sediva L Ruskin JN Josephson ME Prophylactic catheter ablation for the prevention of defibrillator therapy N Engl J Med 2007 357 2657 2665 34. Sacher F, Wright M, Derval N, Denis A, Ramoul K, Roten L, Pascale P, Bordachar P, Ritter P, Hocini M, Dos Santos P, Haissaguerre M, Jais P. Endocardial versus epicardial ventricular radiofrequency ablation: utility of in vivo contact force assessment. Circ Arrhythm Electrophysiol. 2013;6(1):144-50. Sacher F Wright M Derval N Denis A Ramoul K Roten L Pascale P Bordachar P Ritter P Hocini M Dos Santos P Haissaguerre M Jais P Endocardial versus epicardial ventricular radiofrequency ablation: utility of in vivo contact force assessment Circ Arrhythm Electrophysiol 2013 6 1 144 150 35. Di Biase L, Santangeli P, Burkhardt DJ, Bai R, Mohanty P, Carbucicchio C, Dello Russo A, Casella M, Mohanty S, Pump A, Hongo R, Beheiry S, Pelargonio G, Santarelli P, Zucchetti M, Horton R, Sanchez JE, Elayi CS, Lakkireddy D, Tondo C, Natale A. Endo-epicardial homogenization of the scar versus limited substrate ablation for the treatment of electrical storms in patients with ischemic cardiomyopathy. J Am Coll Cardiol. 2012;60(2):132-41. Di Biase L Santangeli P Burkhardt DJ Bai R Mohanty P Carbucicchio C Dello Russo A Casella M Mohanty S Pump A Hongo R Beheiry S Pelargonio G Santarelli P Zucchetti M Horton R Sanchez JE Elayi CS Lakkireddy D Tondo C Natale A Endo-epicardial homogenization of the scar versus limited substrate ablation for the treatment of electrical storms in patients with ischemic cardiomyopathy J Am Coll Cardiol 2012 60 2 132 141 36. Komatsu Y, Sacher F, Cochet H, Jaïs P. Multimodality imaging to improve the safety and efficacy of epicardial ablation of scar-related ventricular tachycardia. J Cardiovasc Electrophysiol. 2013;24(12):1426-7. Komatsu Y Sacher F Cochet H Jaïs P Multimodality imaging to improve the safety and efficacy of epicardial ablation of scar-related ventricular tachycardia J Cardiovasc Electrophysiol 2013 24 12 1426 1427 37. de Chillou C, Groben L, Magnin-Poull I, Andronache M, MagdiAbbas M, Zhang N, Abdelaal A, Ammar S, Sellal JM, Schwartz J, Brembilla-Perrot B, Aliot E, Marchlinski FE. Localizing the critical isthmus of postinfarct ventricular tachycardia: the value of pace-mapping during sinus rhythm. Heart Rhythm. 2014;11(2):175-81. de Chillou C Groben L Magnin-Poull I Andronache M MagdiAbbas M Zhang N Abdelaal A Ammar S Sellal JM Schwartz J Brembilla-Perrot B Aliot E Marchlinski FE Localizing the critical isthmus of postinfarct ventricular tachycardia: the value of pace-mapping during sinus rhythm Heart Rhythm 2014 11 2 175 181 38. Silberbauer J, Oloriz T, Maccabelli G, Tsiachris D, Baratto F, Vergara P, Mizuno H, Bisceglia C, Marzi A, Sora N, Guarracini F, Radinovic A, Cireddu M, Sala S, Gulletta S, Paglino G, Mazzone P, Trevisi N, Della Bella P. Non-Inducibility and Late Potential Abolition: A Novel Combined Prognostic Procedural Endpoint for Catheter Ablation of Post-infarction Ventricular Tachycardia. Circ Arrhythm Electrophysiol. 2014 May 15. pii: CIRCEP.113.001239. Silberbauer J Oloriz T Maccabelli G Tsiachris D Baratto F Vergara P Mizuno H Bisceglia C Marzi A Sora N Guarracini F Radinovic A Cireddu M Sala S Gulletta S Paglino G Mazzone P Trevisi N Della Bella P Non-Inducibility and Late Potential Abolition: A Novel Combined Prognostic Procedural Endpoint for Catheter Ablation of Post-infarction Ventricular Tachycardia Circ Arrhythm Electrophysiol 15 May 2014 pii: CIRCEP.113.001239 39. Henz BD, do Nascimento TA, Dietrich Cde O, Dalegrave C, Hernandes V, Mesas CE, Leite LR, Cirenza C, Asirvatham SJ, de Paola AA. Simultaneous epicardial and endocardial substrate mapping and radiofrequency catheter ablation as first-line treatment for ventricular tachycardia and frequent ICD shocks in chronic chagasic cardiomyopathy. J Interv Card Electrophysiol. 2009;26(3):195-205 Henz BD do Nascimento TA Dietrich Cde O Dalegrave C Hernandes V Mesas CE Leite LR Cirenza C Asirvatham SJ de Paola AA Simultaneous epicardial and endocardial substrate mapping and radiofrequency catheter ablation as first-line treatment for ventricular tachycardia and frequent ICD shocks in chronic chagasic cardiomyopathy J Interv Card Electrophysiol 2009 26 3 195 205 Editorial Ablação Epicárdica de Taquicardia Ventricular na Cardiopatia Chagásica Crônica Scanavacca Mauricio FMUSP HC Instituto do Coração São Paulo SP Brazil Instituto do Coração (InCor) -HC-FMUSP. São Paulo. SP - Brasil Correspondência: Mauricio Scanavacca, Av. Joaquim C. A. Marques, 1.205. CEP 05688-021, Morumbi, SP - Brasil, e-mail: mauricio.scanavacca@gmail.com Cardiomiopatia Chagásica Taquicardia Ventricular Ablação por cateter

A doença de Chagas, descrita pela primeira vez em 1909 por Carlos Chagas, é causada pelo Trypanosoma cruzi, um protozoário flagelado transmitido aos seres humanos, na maioria dos casos pelas fezes de triatomídeos em áreas endêmicas. Estima-se que 15 milhões de pessoas estejam infectadas na América Latina, causando 45 mil mortes por ano, 90% por doença cardíaca.

O envolvimento cardíaco é a manifestação mais frequente e grave da doença de Chagas. Após a infecção, a maioria dos indivíduos permanece sem manifestação da doença ao longo da vida, mas pelo menos 30% desenvolvem múltiplos distúrbios do ritmo cardíaco, sintomas graves de insuficiência cardíaca e fenômenos tromboembólicos, em geral, após 10 a 30 anos da infecção inicial. A miocardite crônica predispõe à dilatação cardíaca e à formação de aneurismas ventriculares. Trombos são frequentes no aneurisma ventricular apical, característico da doença, sendo causa dos fenômenos tromboembólicos na circulação sistêmica e pulmonar. A fibrose miocárdica segmentar é o substrato anatômico para as arritmias ventriculares e distúrbios da condução atrioventricular e intraventricular. A morte súbita ocorre em 55 a 65% dos doentes, por vezes na ausência de sintomas cardíacos anteriores. Morte em consequência de insuficiência cardíaca ocorre em 25 a 30%, e por embolia cerebral ou pulmonar, em 10 a 15%1-3.

Extrassístoles ventriculares são muito comuns em pacientes com cardiopatia chagásica, e sua frequência e complexidade relacionam-se com a extensão do dano miocárdico, em particular com a disfunção e a dilatação do ventrículo esquerdo4. A TV não sustentada tem sido reconhecida como fator de risco independente para morte e incluída em escore para estratificação de risco5. A TV sustentada é considerada a principal causa de morte súbita, podendo ocorrer em diferentes fases da doença e mesmo em pacientes sem disfunção ventricular importante6.

A amiodarona é a droga antiarrítmica mais usada no Brasil para tratar arritmias ventriculares em pacientes com doença de Chagas. Estudos de coorte envolvendo pacientes com doença de Chagas e TV sustentadas mostraram 5 a 11,9% de mortalidade anual, sendo a morte súbita responsável por 61 a 78% dos casos, a maioria com disfunção sistólica ventricular importante7-10. Por essa razão, o cardioversor desfibrilador automático implantável (CDI) tem sido recomendado em pacientes com TV sustentada e disfunção ventricular11-14. No entanto, pacientes com doença de Chagas parecem receber mais choques do CID em comparação com pacientes com doença coronária. Observação importante foi a mortalidade anual de 16,6% em uma coorte de 90 pacientes com cardiopatia chagásica submetidos a implante CDI por TV sustentada. Apesar de os pacientes apresentarem baixa taxa de morte súbita, tiveram expressiva taxa de mortalidade total. Pacientes com mais de quatro choques em um período de 30 dias apresentaram maior mortalidade quando comparados aos pacientes sem ou com menor número de choques11. Uma vez que esses pacientes morreram predominantemente de insuficiência cardíaca, pode-se especular que os choques excessivos aplicados pelo CDI poderiam deprimir a função ventricular e aumentar a mortalidade não súbita. Esses dados corroboram a indicação da ablação por cateter como estratégia lógica para reduzir as recorrências de VT sustentada e evitar os choques do CDI15.

Ablação por cateter da TV sustentada na cardiopatia chagásica

O principal mecanismo da TVS da cardiopatia chagásica crônica é a reentrada localizada em uma cicatriz inferolateral e basal do ventrículo esquerdo em mais de 70% dos casos16,17. O circuito reentrante da TVS pode envolver fibras subendocárdicas, intramiocárdicas e subepicárdicas. Em alguns pacientes, os circuitos reentrantes originam-se em locais com parede muito fina e, assim, pulsos convencionais de RF, emitidos a partir do endocárdio, podem promover lesão transmural e atingir todas as estruturas potencialmente envolvidas no circuito. Em outros, entretanto, a lesão segmentar é intramural e o circuito é mantido predominantemente por fibras subepicárdicas. Sendo o tecido subendocárdico contralateral muito espesso, ele pode impedir que as aplicações de RF alcancem as fibras intramiocárdicas e subepicárdicas responsáveis e ser motivo para o insucesso do procedimento. Essa foi a hipótese inicial de trabalho para utilizarmos a abordagem percutânea subxifoide transtorácica para explorar o espaço pericárdico e identificar os pacientes com possíveis circuitos subepicárdicos15.

 Ablação epicárdica da TV sustentada na cardiopatia chagásica

A abordagem epicárdica transtorácica tem sido utilizada desde 1995 para mapeamento e ablação de TV sustentada em pacientes com doença de Chagas18 e posteriormente aplicada também em pacientes com outras cardiopatias19. A experiência adquirida ao longo do tempo confirmou os achados iniciais20-23, e documentos de consenso emitidos por diferentes sociedades médicas relatam sua necessidade em pelo menos 20% dos pacientes submetidos a ablação de TVS em centros terciários, sendo sua importância maior em pacientes com cardiopatias não isquêmicas24,25. Revisão recente ressalta a importância atual da abordagem percutânea subxifoide em vários procedimentos intrapericárdicos26.

A técnica de acesso ao espaço pericárdico manteve-se praticamente inalterada ao longo do tempo, com quase nenhuma modificação tecnológica para sua realização27. A agulha Tuohy é a principal ferramenta para alcançar o espaço pericárdico (Figura 1). Ela tem ponta curva pouco afiada, que facilita sua introdução entre as membranas pericárdicas (Figura 2). Um risco de 10% de sangramento pericárdico é esperado quando se utiliza essa técnica, em geral de pequena monta e transitório. O risco de sangramento grave requerendo reparação cirúrgica é de cerca de 1 a 2%. Na maioria dos pacientes submetidos a essa abordagem, o mapeamento epicárdico permite ampla área de exploração. Aderências pericárdicas também são incomuns após ablações prévias.

Acesso ao espaço pericárdico normal para mapeamento e ablação epicárdica por punção subxifoide. Em detalhe, a agulha de Tuhoy desenhada para anestesia peridural e usada nesse procedimento para minimizar o risco de perfuração cardíaca. Técnica de acesso ao espaço pericárdico normal. A: Punção subxifoide com agulha de Tuhoy. A compressão do epigástrico facilita a introdução da agulha no espaço pericárdico, diminuindo o risco de perfuração de órgão intra-abdominais, em particular do fígado. B: Fluoroscopia do coração na projeção oblíqua anterior esquerda (OAE) demonstrando o posicionamento correto do fio-guia no espaço pericárdico. C, D, E: Aspectos fluoroscópicos em oblíqua anterior direita (OAD) e OAE do posicionamento do cateter explorador na superfície epicárdica do coração.

Os sinais eletrofisiológicos obtidos durante o mapeamento epicárdico mostram padrões semelhantes aos obtidos com o mapeamento endocárdico, em pacientes com doença de Chagas ou com outras cardiopatias. Potenciais tardios são encontrados com frequência na área-alvo durante o mapeamento em ritmo sinusal e atividade pré-sistólica; atividades mesodiastólica e contínua também são frequentes no local de origem da TV. O istmo crítico do circuito reentrante no tecido subepicárdico pode ser confirmado por manobras de encarrilhamento ou pela interrupção da TV durante a aplicação de RF nesses locais, como observado pela abordagem endocárdica. A prevalência de TV epicárdica em 257 pacientes consecutivos foi maior em pacientes com doença de Chagas (37%), em comparação com pacientes pós-infarto do miocárdio (28%) e pacientes com cardiomiopatia dilatada idiopática (24%)28.

Três aspectos anatômicos da superfície epicárdica podem limitar a eficiência da ablação epicárdica: a presença de artéria coronária epicárdica, uma espessa camada de gordura e o risco de produzir lesão em tecidos vizinhos como o nervo frênico29. Por esses e outros motivos, número substancial de pacientes ainda continua com recorrências clínicas após a ablação endocárdica e epicárdica, seja por limitações encontradas durante o procedimento, seja pela evolução da doença. A taxa de recorrência parece diminuir com a introdução do mapeamento eletroanatômico para estabelecer extensão e limites da cicatriz (Figuras 3 e 4), e ablação com cateteres com ponta irrigada (lesões mais profundas, mesmo na presença de gordura) para promover lesões mais extensas do substrato30. Por outro lado, lesões epicárdicas mais extensas podem aumentar o risco de danificar as artérias coronárias e as estruturas extracardíacas31,32.

Mapeamento eletroanatômico em paciente com taquicardia ventricular sustentada (TVS) secundária a cardiopatia chagásica crônica (CCC). A: ECG em ritmo sinusal. Note que não há distúrbios da condução atrioventricular e intraventricular ou áreas eletricamente inativas, mas apenas alteração da repolarização nas paredes inferior e lateral do ventrículo esquerdo (VE), secundária à cicatriz segmentar localizada nas mesmas regiões (painéis C e D). B: ECG da TVS com padrão eletrocardiográfico sugestivo de origem na região basal do VE (QRS positivo de V1 a V6), com início da ativação ventricular na parede lateral (QRS negativo em DI e aVL e positivo em D2, D3 e aVF). C: Mapeamento eletroanatômico tridimensional da superfície endocárdica e epicárdica do VE em ritmo sinusal com o sistema Carto. As cores representam a amplitude dos eletrogramas ventriculares nas regiões investigadas. Note que a área de baixa voltagem, indicativa da presença de cicatriz, é predominantemente epicárdica. D: Integração do mapa do endocárdio e do epicárdio demonstrando a lesão segmentar inferior lateral e basal do VE, substrato anatômico da TVS nesse paciente. Ablação da TVS no mesmo pacientes da <xref ref-type="fig" rid="f07">Figura 3</xref>. A: Traçado eletrofisiológico documentando o momento da aplicação de pulso de RF pelo cateter epicárdico que interrompe a TVS e restaura o ritmo sinusal. I, II, III, V1 e V6: derivações do ECG sincronizadas com os eletrogramas intracavitários. VD p e VD d: eletrogramas bipolares obtidos pelos eletrodos proximal e distal do ventrículo direito, respectivamente. VE epi p e VE epi d: eletrogramas bipolares obtidos, respectivamente, pelos eletrodos proximal e distal do cateter epicárdico posicionado na cicatriz inferior e lateral do VE. VE endo p: sinal bipolar do cateter introduzido no VE. RF: momento da aplicação da energia de radiofrequência e que interrompe a TVS. A aplicação é mantida por 60 segundos. Velocidade do registro: 25 mm/s. B: Vista posterior do mapa eletroanatômico de voltagem mostrando os limites da cicatriz inferior, lateral e basal do VE. Os pontos roxos e rosa indicam locais com eletrogramas fracionados e tardios durante o ritmo sinusal. Os pontos em verde indicam a transição entre o ventrículo esquerdo e o átrio esquerdo. C: Mesma vista do mapeamento eletroanatômico, mostrando as aplicações de RF (pontos em vermelho) no sítio de origem da TVS.

Um estudo prospectivo e randomizado para avaliar o papel e os riscos de diferentes estratégias durante a ablação por cateter em pacientes com doença de Chagas ainda é necessaria33-38. Entretanto, há um grupo específico de pacientes nos quais a ablação por cateter apresenta benefícios indiscutíveis: pacientes com ICD recebendo múltiplos choques, apesar da terapia adjuvante com fármacos antiarrítmicos. Em tais casos, os resultados clínicos são muito claros na avaliação de curto e médio prazos39. Vale lembrar que a doença de Chagas tem caráter progressivo, e não é incomum ver pacientes com boa função ventricular esquerda com resultado favorável da ablação de TVS retornarem após 5 a 10 anos com disfunção ventricular esquerda e recorrência de nova TVS.