title: Epicardial Radiofrequency Ablation Failure During Ablation Procedures for Ventricular Arrhythmias: Reasons and Implications for Outcomes.
abstract: BACKGROUND
  Radiofrequency ablation (RFA) from the epicardial space for ventricular arrhythmias is limited or impossible in some cases. Reasons for epicardial ablation failure and the effect on outcome have not been systematically analyzed.
  
  
  RESULTS
  We assessed reasons for epicardial RFA failure relative to the anatomic target area and the type of heart disease and assessed the effect of failed epicardial RFA on outcome after ablation procedures for ventricular arrhythmias in a large single-center cohort. Epicardial access was attempted during 309 ablation procedures in 277 patients and was achieved in 291 procedures (94%). Unlimited ablation in an identified target region could be performed in 181 cases (59%), limited ablation was possible in 22 cases (7%), and epicardial ablation was deemed not feasible in 88 cases (28%). Reasons for failed or limited ablation were unsuccessful epicardial access (6%), failure to identify an epicardial target (15%), proximity to a coronary artery (13%), proximity to the phrenic nerve (6%), and complications (<1%). Epicardial RFA was impeded in the majority of cases targeting the left ventricular summit region. Acute complications occurred in 9%. The risk for acute ablation failure was 8.3× higher (4.5-15.0; P<0.001) after no or limited epicardial RFA compared with unlimited RFA, and patients with unlimited epicardial RFA had better recurrence-free survival rates (P<0.001).
  
  
  CONCLUSIONS
  Epicardial RFA for ventricular arrhythmias is often limited even when pericardial access is successful. Variability of success is dependent on the target area, and the presence of factors limiting ablation is associated with worse outcomes.
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA. sbaldinger1@partners.org.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Baldinger
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Kumar
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA.
authors.forename: Chirag R
authors.initials: CR
authors.lastname: Barbhaiya
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA.
authors.forename: Saagar
authors.initials: S
authors.lastname: Mahida
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA.
authors.forename: Laurence M
authors.initials: LM
authors.lastname: Epstein
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA.
authors.forename: Gregory F
authors.initials: GF
authors.lastname: Michaud
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA.
authors.forename: Roy
authors.initials: R
authors.lastname: John
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA.
authors.forename: Usha B
authors.initials: UB
authors.lastname: Tedrow
authors.affiliation: From the Cardiovascular Division, Cardiac Arrhythmia Center, Brigham and Women's Hospital, Boston, MA.
authors.forename: William G
authors.initials: WG
authors.lastname: Stevenson
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D001900:Boston; D017115:Catheter Ablation / Q000009:adverse effects* / Q000401:mortality; D016208:Databases, Factual; D018572:Disease-Free Survival; D056149:Epicardial Mapping; D005260:Female; D006339:Heart Rate; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010496:Pericardium / Q000503:physiopathology / Q000601:surgery*; D012008:Recurrence; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D017211:Treatment Failure; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*
keywords: catheter ablation; complications; epicardium; phrenic nerve; survival rate; tachycardia, ventricular; ventricular premature complexes