title: Outcome of stand-alone thoracoscopic epicardial left atrial posterior box isolation with bipolar radiofrequency energy for longstanding persistent atrial fibrillation.
abstract: BACKGROUND
  Catheter ablation of longstanding (> 1 year) persistent atrial fibrillation (AF) is associated with poor outcome. This might be due to remodelling and fibrosis formation, mainly located in the posterior left atrial (LA) wall. Therefore, we adopted a thoracoscopic epicardial box isolation of the posterior left atrium using bipolar RF energy with intraoperative testing of conduction block.
  
  
  RESULTS
  Bilateral thoracoscopic box isolation was performed with a bipolar RF clamp. Entrance block was defined as absence of a conducted electrogram within the box, while exit block was confirmed by pacing at 10.0 V/2 ms. Ablation outcome was evaluated after 3, 6, 12 and 24 months with 12-lead ECGs and 24-hour Holter recordings. Twenty-five consecutive patients were included (58 ± 7 years, persistent AF duration 1.8 ± 0.9 years). Entrance block was achieved in all patients and exit block confirmed if sinus rhythm was achieved. After 17 ± 7 months, 76 % of the patients (n = 19) were free of AF recurrence. One patient died within 1 month and was considered an ablation failure. Four patients with AF recurrences regained sinus rhythm with additional catheter ablation or antiarrhythmic drugs.
  
  
  CONCLUSIONS
  Treatment of longstanding persistent AF with thoracoscopic epicardial LA posterior box isolation using bipolar RF energy with intraoperative testing of conduction block is feasible and highly effective.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, PO Box 9600, Leiden, The Netherlands.
authors.forename: M G
authors.initials: MG
authors.lastname: Compier
authors.affiliation: Department of Cardiothoracic Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Braun
authors.affiliation: Department of Cardio-thoracic Surgery, Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Tjon
authors.affiliation: Department of Cardiology, Leiden University Medical Center, PO Box 9600, Leiden, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Zeppenfeld
authors.affiliation: Department of Cardiothoracic Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: R J M
authors.initials: RJ
authors.lastname: Klautz
authors.affiliation: Department of Cardiology, Leiden University Medical Center, PO Box 9600, Leiden, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Schalij
authors.affiliation: Department of Cardiology, Leiden University Medical Center, PO Box 9600, Leiden, The Netherlands. mariekecompier@gmail.com.
authors.forename: S A
authors.initials: SA
authors.lastname: Trines
keywords: Atrial fibrillation; Box isolation; Posterior left atrium; Surgical ablation