title: Clinical significance of complete conduction block of the left lateral isthmus and its relationship with anatomical variation of the vein of Marshall in patients with nonparoxysmal atrial fibrillation.
abstract: BACKGROUND
  The vein of Marshall (VOM), which exists along the left lateral isthmus (LLI), constitutes a muscular connection between the coronary sinus (CS) and the left atrium (LA). We hypothesized that anatomical variation of the VOM affects the bidirectional block of LLI and the clinical outcome in patients with nonparoxysmal atrial fibrillation (NPAF).
  
  
  METHODS
  Among 73 patients with NPAF, 54 patients (47 male, 54.1 +/- 10.4 years old) with a clearly visible VOM (74.0%) were included. After circumferential antral ablation, double linear endocardial ablation of LLI was performed along the VOM. Unless LLI block was achievable by endocardial ablation, the ablation was performed inside the CS.
  
  
  RESULTS
  LLI block was achievable in 35 patients (64.8%; 11.1% by endocardial ablation vs 53.7% by additional inside CS ablation; P < 0.01). In patients with failed LLI block, the VOM was significantly longer (P < 0.05) on the right anterior oblique (RAO) view than in those with successful LLI block. LA volume or LLI length measured by CT image were not different (P = NS). During 11.4 +/- 5.0 months follow-up, early recurrences within 3 months (47.4% vs 28.6%, P = NS) and recurrences after 3 months (10.5% vs 17.7%, P = NS) were not different with or without LLI block.
  
  
  CONCLUSIONS
  LLI block, which is more difficult to achieve in patients with a longer VOM, was achievable in 65% of patients with NPAF by linear ablation along the VOM and additional inside CS ablation, but did not affect the short-term clinical outcome.
authors.affiliation: Korea University Cardiovascular Center, Seoul, Republic of Korea.
authors.forename: Jong-Il
authors.initials: JI
authors.lastname: Choi
authors.forename: Hui-Nam
authors.initials: HN
authors.lastname: Pak
authors.forename: Jae Hyung
authors.initials: JH
authors.lastname: Park
authors.forename: Eun Jeong
authors.initials: EJ
authors.lastname: Choi
authors.forename: Sook Kyoung
authors.initials: SK
authors.lastname: Kim
authors.forename: Jae Jin
authors.initials: JJ
authors.lastname: Kwak
authors.forename: Jin Kun
authors.initials: JK
authors.lastname: Jang
authors.forename: Chun
authors.initials: C
authors.lastname: Hwang
authors.forename: Young-Hoon
authors.initials: YH
authors.lastname: Kim
mesh_terms: D001281:Atrial Fibrillation / Q000150:complications / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D003330:Coronary Vessel Anomalies / Q000150:complications / Q000601:surgery*; D005260:Female; D006329:Heart Conduction System / Q000002:abnormalities* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D016896:Treatment Outcome; D014680:Veins / Q000002:abnormalities / Q000601:surgery