57 (27%) limited or no EPI RFA 9 persistent bleeding after access Prevalence and Reasons for Not Performing Epicardial Ablation in Patients with Nonischemic Cardiomyopathy Following Attempted or Successful Access Pasquale Santangeli, MD, PhD; Erica S. Zado, PA-C; Daniele Muser, MD; David S. Frankel, MD; Gregory E. Supple, MD; Robert D. Schaller, DO; Fermin C. Garcia, MD; Mathew D. Hutchinson, MD; David Lin, MD; Michael P. Riley, MD, PhD, Sanjay Dixit, MD, PhD; David J. Callans, MD; Francis E. Marchlinski, MD Electrophysiology Section, Division of Cardiology, Hospital of the University of Pennsylvania, Philadelphia, PA INTRODUCTION Decision for an epicardial approach was made when: The 12-lead ECG of the VT suggested an epicardial origin. There was evidence of epicardial substrate on imaging studies (e.g., magnetic resonance, intracardiac echocardiography [ICE]). Failure of endocardial ablation procedure. Hemodynamically tolerated VT(s) targeted with entrainment mapping. Hemodynamically unstable VT(s) targeted with substrate modification performed with linear and/or cluster lesions targeting sites identified by pace mapping and late potentials. Table 1. General characteristics of the study population Age, yeras 58±13 Male sex 155 (84%) LVEF, % 34±15% NYHA class III-IV 36 (20%) History of atrial fibrillation/flutter 55 (30%) Chronic renal disease 32 (17%) VT storm at presentation 48 (26%) Medical therapy   Beta-blockers 153 (83%) Ace inhibitors/angiontensin receptor blockers 109 (59%) Spironolactone 39 (21%) Furosemide daily dose, mg 43±26 Anti-arrhytmic drugs attempet 2 (1-3) Amiodarone therapy 95 (52%) Type of cardiomyopathy Idiopathic dilated 151 (82%) Sarcoid 14 (8%) Hypertrophic cardiomyopathy 6 (3%) Neuromuscular disorders 1 (0.5%) Previous myocarditis 4 (2%) Non compaction cardiomyopathy Previous radiotherapy/chemotherapy 2 (1%) Ethanol induced Valvular cardiomyopathy 225 Procedures 184 pts Patients with nonischemic cardiomyopathy (NICM) have a high prevalence of epicardial (EPI) substrates, and EPI radiofrequency catheter ablation (RFCA) has been associated with improved VT-free survival in this population. In some cases, EPI ablation is limited or not possible. We report the prevalence and reasons for failed EPI ablation in patients with NICM. 209 Procedures 171 pts 16 EPI not completed 57 (27%) limited or no EPI RFA 9 persistent bleeding after access 6 unsuccessful 152 (73%) with EPI RFA No substrate/good targets 39 Proximity to coronary 13 Phrenic nerve capture 3 Pericardial adhesions 2 Figure 1. Diagram showing the reasons for not performing epicardial ablation in the patients included in the study. METHODS Study population The study cohort comprised 184 consecutive patients (age 58±13 years, 83% males, mean ejection fraction 34±15%) who underwent a total of 225 EPI procedures for scar-related VT in the setting of nonischemic cardiomyopathy at the Hospital of the University of Pennsylvania between Jan-2005 and Dec-2013 (Table 1). Electrophysiologic study and RFCA Access to the pericardial space and epicardium was obtained using a percutaneous subxiphoid approach. The preferred approach to EPI access was posterior. General anesthesia was induced for the EPI access, mapping and ablation. RESULTS A total of 16 (7%) EPI procedures could not be completed because of either unsuccessful attempts at obtaining access (6/16, 38%) or periprocedural complications (10/16, 63%). The latter included 9 patients with persistent bleeding. Out of the remaining 209 procedures, 57 (27%) received no EPI ablation because of lack of abnormal substrate or good EPI targets (68%), proximity to a major coronary artery (23%), phrenic nerve capture (5%) and significant pericardial adhesions limiting mapping (4%) (Figure 1). Figure 3. Left panel: Inability to obtain access to a left basal-lateral epicardial substrate in a patient pericardial adhesions. Right Panel: Contrast injection in the pericardial space shows loculated RV pericardial compartment. CONCLUSIONS In patients with NICM, EPI ablation is limited or impossible in up to one third of cases. Reasons for not performing EPI ablation include: lack of abnormal substrate and/or good ablation targets, safety concerns, inability to obtain access or periprocedural complications related to access. Table 1. General characteristics of the study population Age, yeras 58±13 Male sex 155 (84%) LVEF, % 34±15% NYHA class III-IV 36 (20%) History of atrial fibrillation/flutter 55 (30%) Chronic renal disease 32 (17%) VT storm at presentation 48 (26%) Medical therapy   Beta-blockers 153 (83%) Ace inhibitors/angiontensin receptor blockers 109 (59%) Spironolactone 39 (21%) Furosemide daily dose, mg 43±26 Anti-arrhytmic drugs attempet 2 (1-3) Amiodarone therapy 95 (52%) Type of cardiomyopathy Idiopathic dilated 151 (82%) Sarcoid 14 (8%) Hypertrophic cardiomyopathy 6 (3%) Neuromuscular disorders 1 (0.5%) Previous myocarditis 4 (2%) Non compaction cardiomyopathy Previous radiotherapy/chemotherapy 2 (1%) Ethanol induced Valvular cardiomyopathy Table 1. General characteristics of the study population Age, yeras 58±13 Male sex 155 (84%) LVEF, % 34±15% NYHA class III-IV 36 (20%) History of atrial fibrillation/flutter 55 (30%) Chronic renal disease 32 (17%) VT storm at presentation 48 (26%) Medical therapy   Beta-blockers 153 (83%) Ace inhibitors/angiontensin receptor blockers 109 (59%) Spironolactone 39 (21%) Furosemide daily dose, mg 43±26 Anti-arrhytmic drugs attempet 2 (1-3) Amiodarone therapy 95 (52%) Type of cardiomyopathy Idiopathic dilated 151 (82%) Sarcoid 14 (8%) Hypertrophic cardiomyopathy 6 (3%) Neuromuscular disorders 1 (0.5%) Previous myocarditis 4 (2%) Non compaction cardiomyopathy Previous radiotherapy/chemotherapy 2 (1%) Ethanol induced Valvular cardiomyopathy DISCLOSURES Figure 2. Endocardial and epicardial bipolar voltage map in a patient with NICM and recurrent VT showing no evidence of abnormal substrate. None pertinent to the study.