Competing autonomic mechanisms precede the onset of postoperative atrial fibrillation

J Am Coll Cardiol. 2003 Oct 1;42(7):1262-8. doi: 10.1016/s0735-1097(03)00955-0.


Objectives: This study was designed to evaluate autonomic changes preceding atrial fibrillation/flutter (AF) after thoracotomy.

Background: Autonomic fluctuations before the onset of postoperative AF have been reported but with conflicting results.

Methods: In 48 patients with postoperative AF, 2-h Holter recordings before the onset of AF were compared with corresponding data from 48 age- and gender-matched surgical controls without AF. Five-minute segments of heart rate variability (HRV) were studied using linear regression methods.

Results: There was a near-significant trend for the RR interval among patients with AF to be lower than controls (p = 0.06), whereas the standard deviation of RRs (p < 0.0001), root mean square of successive RR differences (p < 0.0001), proportion of RRs >50 ms different (p < 0.0001), low-frequency power (p = 0.0003) and its log (p < 0.0001), and high-frequency-power (p < 0.0001) and its log (p < 0.0001) were all significantly greater in patients with AF, respectively. In comparison to controls, AF patients had a significant decrease in RR interval (p = 0.02) and significant increments in all time- and frequency-domain analyses studied.

Conclusions: In the period before the onset of postoperative AF, there are significant increases in HRV during a time when heart rate also increases. These novel findings are consistent with parasympathetic resurgence competing with increasing sympathetic activity as the triggering mechanism for postoperative AF.

MeSH terms

  • Aged
  • Atrial Fibrillation / physiopathology*
  • Autonomic Nervous System / physiopathology*
  • Case-Control Studies
  • Electrocardiography, Ambulatory
  • Female
  • Heart Rate
  • Humans
  • Male
  • Postoperative Complications / physiopathology*
  • Prospective Studies
  • Thoracic Surgical Procedures*