title: The feasibility of a Box isolation strategy for non-paroxysmal atrial fibrillation in elderly patients.
abstract: BACKGROUND
  Catheter ablation of non-paroxysmal atrial fibrillation (non-PAF) is a therapeutic challenge especially in elderly patients. This study describes the feasibility of a posterior left atrium isolation as a substrate modification in addition to pulmonary vein isolation, the so-called Box isolation, for elderly patients with non-PAF.
  
  
  METHODS
  Two hundred twenty-nine consecutive patients who underwent Box isolations for drug-refractory non-PAF were divided into two groups according to their age; younger group comprising 175 patients aged <75 years and elderly group comprising 54 patients aged ≥75 years.
  
  
  RESULTS
  During 23.7±12.0 months of follow-up, the arrhythmia-free rates after one procedure were 53.1% in younger group versus 48.1% in elderly group (p=0.50). Following the second procedure, all patients had electrical conduction recoveries along the initial Box lesion. However, a complete Box re-isolation was highly established in both age groups (87.1% vs. 92.9%, respectively; p=1.00). Recurrence of macro-reentrant atrial tachycardia was mainly associated with the gaps through the initial Box lesion in both age groups (25.8% vs. 21.4%, p=1.00), but typical cavo-tricuspid isthmus (CTI) dependent atrial flutter was significantly observed in the elderly patients' group only (all events were observed within 6 months after the initial procedure; 3.2% vs. 28.6%, p=0.009). After two procedures, the arrhythmia-free rates increased to 73.1% in younger group versus 66.7% in elderly group (p=0.38). The occurrence rate of procedural-related complications did not differ between the two age groups, and there were no life-threatening complications even in elderly patients.
  
  
  CONCLUSIONS
  Box isolation of non-PAF is effective and safe even in elderly patients. A prophylactic CTI ablation combined with Box isolation might be feasible to improve the long-term outcome.
authors.affiliation: The Heart Rhythm Center, Hayama Heart Center, 1898-1 Shimoyamaguchi, Hayama-cho, Miura-gun, Kanagawa 240-0116, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Higuchi
authors.affiliation: The Heart Rhythm Center, Hayama Heart Center, 1898-1 Shimoyamaguchi, Hayama-cho, Miura-gun, Kanagawa 240-0116, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sohara
authors.affiliation: The Heart Rhythm Center, Hayama Heart Center, 1898-1 Shimoyamaguchi, Hayama-cho, Miura-gun, Kanagawa 240-0116, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: The Heart Rhythm Center, Hayama Heart Center, 1898-1 Shimoyamaguchi, Hayama-cho, Miura-gun, Kanagawa 240-0116, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Ihara
authors.affiliation: The Heart Rhythm Center, Hayama Heart Center, 1898-1 Shimoyamaguchi, Hayama-cho, Miura-gun, Kanagawa 240-0116, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Department of Cardiology, Tokyo Women׳s Medical University, 8-1, Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Shoda
authors.affiliation: Department of Cardiology, Tokyo Women׳s Medical University, 8-1, Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan.
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Hagiwara
authors.affiliation: The Heart Rhythm Center, Hayama Heart Center, 1898-1 Shimoyamaguchi, Hayama-cho, Miura-gun, Kanagawa 240-0116, Japan.
authors.forename: Shutaro
authors.initials: S
authors.lastname: Satake
keywords: Atrial fibrillation; Box isolation; Catheter ablation; Elderly patient; Typical atrial flutter