title: Long-term effects of box isolation on sympathovagal balance in atrial fibrillation.
abstract: BACKGROUND
  Complete isolation of the posterior left atrium, including all pulmonary veins (box isolation), is a feasible and safe atrial fibrillation (AF) treatment method. Data on long-term effects of box isolation on autonomic function, however, remain limited.
  
  
  RESULTS
  A total of 92 patients (paroxysmal AF, n=76; persistent AF, n=16) undergoing box isolation with non-contact mapping were studied. Twenty-four-hours ambulatory electrocardiograms and transthoracic echocardiography were done at baseline and after 2 days, and at 3, 6 and 12 months. Autonomic functions were evaluated by means of heart rate variability (HRV). During a mean follow up of 16+/-5 months, no AF episodes were detected in 76 patients while AF recurred in 16. Significant long-term HRV attenuations were observed in all patients without AF recurrence, but not in those with AF recurrence. In patients without AF recurrence, the natural logarithm (Ln) high-frequency (HF) decreased significantly from 5.5+/-1.3 ms(2) (before) to 4.2+/-0.9 ms(2) (after 12 months, P<0.001) and the ratio of the low-frequency to HF power increased significantly from 2.4+/-2.0 (before) to 3.4+/-2.3 (after 12 months, P=0.05). LnHF was significantly lower in patients without than in those with AF recurrence during the 12-month period after ablation. Cardiac function improved significantly in patients without AF recurrence after box isolation.
  
  
  CONCLUSIONS
  Changes in the sympathovagal balance with box isolation may contribute to AF prevention.
authors.affiliation: Department of Cardiology, Fukuoka University School of Medicine, Fukuoka, Japan. yoshio-y@krc.biglobe.ne.jp
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Koichiro
authors.initials: K
authors.lastname: Kumagai
authors.forename: Hideko
authors.initials: H
authors.lastname: Nakashima
authors.forename: Keijiro
authors.initials: K
authors.lastname: Saku
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000517:prevention & control / Q000601:surgery*; D017763:Autonomic Denervation / Q000379:methods*; D006348:Cardiac Surgical Procedures / Q000379:methods*; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery*; D006334:Heart Function Tests; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013997:Time Factors; D014630:Vagus Nerve / Q000503:physiopathology*