title: Organized left atrial tachyarrhythmia during stepwise linear ablation for atrial fibrillation.
abstract: BACKGROUND
  This study attempted to delineate the mechanism of organized left atrial tachyarrhythmia (AT) during stepwise linear ablation for atrial fibrillation (AF) using noncontact mapping.
  
  
  RESULTS
  Eighty patients in whom organized ATs developed or induced during stepwise linear ablation for AF were enrolled. Left atrial (LA) activation during ATs was mapped using noncontact mapping. Radiofrequency (RF) energy was delivered to the earliest activation site or narrowest part of the reentrant circuit of ATs. A total of 146 ATs were mapped. Four ATs were characterized as a focal mechanism (cycle length (CL): 225 +/- 49 ms). A macroreentrant mechanism was confirmed in the remaining 142 ATs. LA activation time accounted for 100% of CL (205 +/- 37 ms). All 142 ATs used the conduction gaps in the basic figure-7 lesion line. There were three types of circuits classified based on the gap location. Type I (n = 68) used gaps at the ridge between left atrial appendage (LAA) and left superior pulmonary vein (LSPV). Type II (n = 50) used gaps on the LA roof. Type III (n = 24) passed through gaps in the mitral isthmus. Ablation at these gaps eliminated 130 ATs. During the follow-up period of 16.2 +/- 6.7 months, 82.5% of the 80 patients were in sinus rhythm.
  
  
  CONCLUSIONS
  The majority of left ATs developed during stepwise linear ablation for AF are macroreentrant through conduction gaps in the figure-7 lesion line, especially at the LAA-LSPV ridge. Noncontact activation mapping can identify these gaps accurately and quickly to target effective catheter ablation.
authors.affiliation: Clinical EP Laboratory and Arrhythmia Center, Fuwai Hospital and Cardiovascular Institute, Peking Union Medical College (PUMC)-Chinese Academy of Medical Sciences (CAMS), Beijing, China.
authors.forename: Lihui
authors.initials: L
authors.lastname: Zheng
authors.forename: Yan
authors.initials: Y
authors.lastname: Yao
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.forename: Wensheng
authors.initials: W
authors.lastname: Chen
authors.forename: Kuijun
authors.initials: K
authors.lastname: Zhang
authors.forename: Fangzheng
authors.initials: F
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.forename: Ding Sheng
authors.initials: DS
authors.lastname: He
authors.forename: Alan H
authors.initials: AH
authors.lastname: Kadish
mesh_terms: D001281:Atrial Fibrillation / Q000150:complications / Q000601:surgery*; D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013612:Tachycardia, Ectopic Atrial / Q000209:etiology* / Q000517:prevention & control*; D016896:Treatment Outcome