title: Completion of mitral isthmus ablation using a steerable sheath: prospective randomized comparison with a nonsteerable sheath.
abstract: BACKGROUND
  Although mitral isthmus (MI) ablation in atrial fibrillation (AF) patients has been shown to be an effective ablative strategy, the establishment of the bidirectional conduction block of the MI is technically challenging. We investigated the usefulness of a steerable sheath for MI ablation in patients with persistent AF and its impact on the clinical outcome of persistent AF ablation.
  
  
  METHODS
  A total of 80 consecutive patients undergoing MI ablation were randomized to 1 of the following 2 groups: group S (using a steerable long sheath) or group NS (using a nonsteerable long sheath). MI ablation was performed by using an open-irrigated ablation catheter with the guidance of a 3-dimensional mapping system. The endpoint of the MI ablation was the achievement of a bidirectional block.
  
  
  RESULTS
  Bidirectional block through the MI was achieved in 87.5% (70/80) of patients with 14.0 ± 6.7 minutes of radiofrequency application. The bidirectional block was more frequently achieved in patients in group S compared to group NS (97.5% (39/40) vs 77.5% (31/40), P = 0.02). Additionally, epicardial ablation within the coronary sinus was less frequently required in group S compared to group NS (12.5% (5/40) vs 72.5% (29/40), P < 0.0001). Atrial tachycardia after the procedure more frequently occurred in the patients in whom MI block had not been achieved during the initial procedure (40.0% (4/10) vs 10.0% (7/70), P = 0.04).
  
  
  CONCLUSIONS
  The MI block could be achieved in the majority of patients by using a steerable sheath. An incomplete MI block increased the risk of AT following persistent AF ablation.
authors.affiliation: Department of Cardiology, The Jikei University School of Medicine, Tokyo, Japan. mattsuu@tc4.so-net.ne.jp
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Matsuo
authors.forename: Teiichi
authors.initials: T
authors.lastname: Yamane
authors.forename: Taro
authors.initials: T
authors.lastname: Date
authors.forename: Mika
authors.initials: M
authors.lastname: Hioki
authors.forename: Ryohsuke
authors.initials: R
authors.lastname: Narui
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ito
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Tanigawa
authors.forename: Tokiko
authors.initials: T
authors.lastname: Nakane
authors.forename: Seigo
authors.initials: S
authors.lastname: Yamashita
authors.forename: Michifumi
authors.initials: M
authors.lastname: Tokuda
authors.forename: Keiichi
authors.initials: K
authors.lastname: Inada
authors.forename: Ayumi
authors.initials: A
authors.lastname: Nojiri
authors.forename: Makoto
authors.initials: M
authors.lastname: Kawai
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Michihiro
authors.initials: M
authors.lastname: Yoshimura
mesh_terms: D001281:Atrial Fibrillation / Q000601:surgery*; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged