title: High Atrial Defibrillation Threshold With Internal Cardioversion Indicates Arrhythmogenicity of Superior Vena Cava in Non-Long-Standing Persistent Atrial Fibrillation.
abstract: BACKGROUND
  The purpose of this study was to clarify the relation between atrial defibrillation threshold (ADFT) for internal cardioversion (IC) and arrhythmogenicity of the superior vena cava (SVC).
  
  
  RESULTS
  A total of 159 consecutive patients (139 male, age 59.9±10.3 years) who underwent radiofrequency catheter ablation of atrial fibrillation (AF) were assessed. IC was performed in 50 patients with non-long-standing persistent AF (non-LSAF) with a purpose-built cardioversion catheter in which direct current is delivered between the right atrium and the coronary sinus. SVC arrhythmogenicity was defined as SVC firing initiating AF, SVC associated with maintenance of AF, or frequent ectopy in the SVC. In all 50 non-LSAF patients, AF termination was obtained on IC during the procedure except in 1 patient with SVC AF. In the patients with ADFT >10 J (n=10), SVC arrhythmogenicity was observed more often than in those with ADFT ≤10 J (n=40; 60% vs. 13%; P=0.004). There were no significant differences between the 2 groups in left atrial diameter (40.8±7.6 vs. 40.6±6.3 mm; P=0.92), persistent AF (33% vs. 50%; P=0.46), or other clinical parameters. The patients who underwent SVC isolation, however, had higher ADFT before SVC isolation than those who did not (15.5±8.8 vs. 9.2±4.4 J; P=0.01).
  
  
  CONCLUSIONS
  High IC ADFT is associated with SVC arrhythmogenicity in non-LSAF patients.
authors.affiliation: Department of Cardiovascular Medicine, Tokyo Medical and Dental University.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Ihara
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sasaki
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Shirai
authors.forename: Susumu
authors.initials: S
authors.lastname: Tao
authors.forename: Shingo
authors.initials: S
authors.lastname: Maeda
authors.forename: Mihoko
authors.initials: M
authors.lastname: Kawabata
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Sasano
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yokoyama
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Isobe
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hirao
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy*; D017115:Catheter Ablation / Q000379:methods; D004554:Electric Countershock / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014683:Vena Cava, Superior / Q000503:physiopathology*