EPICARDIAL ARRHYTMOGENIC SUBSTRATE IN PATIENTS WITH POSTINFARCTION VENTRICULAR TACHYCARDIA: A PILOT STUDY

Introduction: radiofrequency ablation (RFA) is an established treatment of post-myocardial infarction ventricular tachycardia (VT). Endocardial VT ablation can be insuffi cient for VT termination when the scar is intramural/epicardial.
Purpose: to assess the extent of epicardial electrophysiological VT substrate in patients with remote myocardial infarction.
Materials and methods: thirteen patients with sustained postinfarction VT, who signed an informed consent, were included into the study. All patients underwent full clinical evaluation. Electroanatomical voltage bi- and unipolar mapping (EAVM) of endocardial and epicardial surfaces was performed. Maps were evaluated for the presence of low-voltage areas and local abnormal ventricular activity (LAVA). RFA was performed at LAVA sites. The end-point of the procedure was scar LAVA abolition and VT noninducibility (procedure success). VT recurrence was detected using an implantable cardioverter-defi brillator and/or ECG monitoring.

Results: epicardial access was successful in 12 patients. Epicardial access was performed at a fi rst procedure in 7 patients, 4 patients had a history of previous endocardial ablation. Epicardial LAVA sites were detected in 9 patients. Endocardial and epicardial arrhythmogenic substrate localization coincided in 8 patients. One patient had only epicardial scar, 1 patient had only septal endocardial scar. In one patient LAVA sites had different localizations on epicardial and endocardial maps. Acute ablation success was noted in 12 patients.
Conclusion: in our patient group transmural scar and epicardial electrophysiological arrhythmogenic substrate was detected in 82% of cases. Isolated endocardial ablation may be unsuccessful, in such cases epicardial mapping and ablation might be useful.

1. Guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines/ Zipes D.P.[et al]. - 2006. - 48. - P. 247- 346

2. Comparison of beta-blockers, amiodarone plus betablockers, or sotalol for prevention of shocks from implantable cardioverter defi brillators: the OPTIC Study: a randomized trial/ Connolly S.J. [et al.]//Journal of the American Medical Association. - 2006. - 295. - P.165-171.

3. Nonsurgical transthoracic epicardial radiofrequency ablation: an alternative in incessant ventricular tachycardia/Brugada J. // Journal of the American College of Cardiology. - 2003. - 41. - P. 2036 -2043.

4. Successful catheter ablation of electrical storm after myocardial infarction/ Bansch D. [et al.]// Circulation. - 2003. - 108. - P. 3011-3016.

5. Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction/ Sosa E. [et al.]//Journal of the American College of Cardiology. - 2000. - 35. - P.1442-1449.

6. Ventricular tachycardia in ischemic cardiomyopathy; a combined endo-epicardial ablation as the fi rst procedure versus a stepwise approach (EPILOGUE) - study protocol for a randomized controlled trial. Trials/ Hendriks A. [et al.]. - 2015. - 16. - P. 487. https://doi.org/10.1186/s13063-015-1005-6

7. Core isolation of sritical arrhythmia elements for treatment of multiple scar-based ventricular tachycardias / Tzou W. [et al.]// Circulation: Arrhythmia and Electrophysiology. - 2015. - 8(2). - P.353-361. https://doi.org/10.1161/CIRCEP.114.002310

8. Substrate-modifi cation using electroanatomical mapping in sinus rhythm to treat ventricular tachycardia in patients with ischemic cardiomyopathy/ Deneke T. [et al.] Zeitschrift für Kardiologie. - 2005. - 94. - P. 453- 460

9. Catheter ablation of ventricular tachycardia following myocardial infarction using threedimensional electroanatomical mapping/ Kautzner J. [et al.]// Pacing and Clinical Electrophysiology. - 2003. - 26. - 342-347

10. Noninducibility and late potential abolition: a novel combined prognostic procedural end point for catheter ablation of postinfarction ventricular tachycardia/ Silberbauer J. [et al.] // Circulation: Arrhythmia and Electrophysiology. - 2014. - 7. - P. 424-435. https://doi.org/10.1161/CIRCEP.113.001239

11. Biophysics of Ablation: Application to Technology/ Haines D. [et al.] // Journal of Cardiovascular Electrophysiology. - 15(10). - P.2-11. https://doi.org/10.1046/j.1540-8167.2004.15102.x

12. Radiochastotnaya kateternaya ablatsiya: biofizicheskie osnovy i patofiziologicheskie aspekty/V.I. Steklov [i dr.]//Vestnik aritmologii. - 2018. - Vyp. 94. - s. 47-56

13. Simonova, K.A. Rol' epikardial'nogo kartirovaniya i ablatsii v lechenii zheludochkovykh takhikardii/ K.A. Simonova, D. S. Lebedev, E. N. Mikhailov // Kompleksnye problemy serdechno-sosudistykh zabolevanii. - 2017. - T. 6, № 4

14. Endo-epicardial homogenization of the scar versus limited substrate ablation for the treatment of electrical storms in patients with ischemic cardiomyopathy/ Di Biase L. [et al.]// Journal of the American College of Cardiology. - 2012. - 60(2). - P. 132-141. https://doi.org/10.1016/j.jacc.2012.03.04

15. Nonsurgical transthoracic epicardial radiofrequency ablation: An alternative in incessant ventricular tachycardia / Brugada J. [et al.]// Journal of the American College of Cardiology - 2003. - 41. - P. 2036-2043

16. Epicardial Ventricular Tachycardia in Ischemic Cardiomyopathy: Prevalence, Electrophysiological Characteristics, and Long-term Ablation Outcomes/ Hayashi T. [et al.]//Journal of Cardiovascular Electrophysiology. - 2018. - 29. - P. 1530-1539 https://doi.org/10.1111/jce.13739

17. Epicardial Ablation of Ventricular Tachycardia: a Review/Cardoso R. [et al.]//Korean Circulaion Journal. - 2018. - 48(9). - P. 778-791. https://doi.org/10.4070/kcj.2018.0210

18. Characterization of the Arrhythmogenic Substrate in Ischemic and Nonischemic Cardiomyopathy: Implications for Catheter Ablation of Hemodynamically Unstable Ventricular Tachycardia/ Nakahara S. [et al.]// Journal of the American College of Cardiology. - 2010. - 55(21). - P. 2355-2365. https://doi.org/10.1016/j.jacc.2010.01.041.

19. Catheter ablation for ventricular tachycardia after failed endocardial ablation: epicardial substrate or inappropriate endocardial ablation? / Schmidt B. [et al.]//Heart Rhythm. - 2010. - 7(12). - P.1746-1752. https://doi.org/0.1016/j.hrthm.2010.08.010

20. Electrocardiographic recognition of the epicardial origin of ventricular tachycardias/ Berruezo A. [et al.]// Circulation. - 2004. - 20109(15):1842-1847. https://doi.org/10.1161/01.CIR.0000125525.04081.4B

21. Epicardial Catheter Ablation of Ventricular Tachycardia/ Aryana A. // Cardiac Electrophysiology Clinics. - 2017. - 9(1). - P. 119-131. https://doi.org/10.1016/j.ccep.2016.10.009