title: How does successful off-pump pulmonary vein isolation for paroxysmal atrial fibrillation influence heart rate variability and autonomic activity?
abstract: OBJECTIVE
  : Surgical pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) blocks trigger stimulation from PVs and partially disconnects the atria from sympathetic and parasympathetic neural stimulation. This study describes long-term changes in heart rate variability (HRV) and autonomic activity (AA) after successful bipolar radiofrequency PVI.
  
  
  METHODS
  : Twenty-seven patients who underwent coronary artery bypass grafting and successful (defined as stable sinus rhythm for 1 year) off-pump bipolar radiofrequency PVI for PAF were prospectively followed 3, 6, and 12 months after surgery including 24 hours Holter electrocardiogram. The following HRV and AA parameters were calculated: mean NN-interval, SD of NN-intervals, SD of averaged NN-intervals, root mean square of successive differences, low frequency (LF) power (0.04-0.15 Hz; a parameter specific for sympathetic activity), high frequency (HF) power (0.15-0.4 Hz; a parameter specific for parasympathetic activity), and the LF:HF ratio.
  
  
  RESULTS
  : Preoperatively, high HRV and AA parameters were recorded. In 3-, 6-, and 12-month time, a progressive reduction of HRV and AA was observed, reaching significance after 12 months. Respective rates before surgery and 12 months after it were: for SD of averaged NN-intervals (122.4 ± 113; 80.5 ± 42 milliseconds; P = 0.046), for root mean square of successive differences (79.2 ± 93; 45 ± 20 milliseconds; P = 0.04). The LF:HF ratios were 1.22 and 0.73 before and 12 months after surgery, respectively. The statistically significant continuous reduction in LF:HF ratio (P = 0.02) is suggestive of a progressive parasympathetic dominance 12 months after surgery.
  
  
  CONCLUSIONS
  : Successful PVI for PAF results in HRV and sympathetic activity reduction with preoperative sympathetic dominance and oncoming vagal dominance after 1 year from surgery. Despite preoperative sympathetic dominance, successful PVI for PAF results in HRV and a reduction in sympathetic activity with emerging parasympathetic dominance 12 months after surgery.
authors.affiliation: From the *Department of Cardiac Surgery, 1st Chair of Cardiology, Medical University of Warsaw, Warsaw, Poland; and †Department of Cardiovascular Surgery, University Medical Centre Ljubljana, Ljubljana, Slovenia.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Suwalski
authors.forename: Piotr
authors.initials: P
authors.lastname: Suwalski
authors.forename: Jurij M
authors.initials: JM
authors.lastname: Kalisnik
authors.forename: Mariusz
authors.initials: M
authors.lastname: Sledz
authors.forename: Julita
authors.initials: J
authors.lastname: Switaj
authors.forename: Marcin
authors.initials: M
authors.lastname: Czachor
authors.forename: Borut
authors.initials: B
authors.lastname: Gersak
authors.forename: Kazimierz B
authors.initials: KB
authors.lastname: Suwalski