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.
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.
Choi
Jong-Il
JI
Korea University Cardiovascular Center, Seoul, Republic of Korea.
Pak
Hui-Nam
HN
Park
Jae Hyung
JH
Choi
Eun Jeong
EJ
Kim
Sook Kyoung
SK
Kwak
Jae Jin
JJ
Jang
Jin Kun
JK
Hwang
Chun
C
Kim
Young-Hoon
YH
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