The role of chronic atrial stretch and atrial fibrillation on posterior left atrial wall conduction

Kurt C. Roberts-Thomson, Irene Stevenson, Peter M. Kistler, Haris M. Haqqani, Steven J. Spence, John C. Goldblatt, Prashanthan Sanders, Jonathan M. Kalman

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77 Citations (Scopus)

Abstract

Background: The posterior left atrium (LA) is involved in the initiation and maintenance of atrial fibrillation (AF). Objective: The purpose of this study was to compare conduction patterns on the posterior LA in patients with mitral regurgitation (MR), with and without AF. Methods: Epicardial mapping of the posterior LA was performed in 23 patients undergoing cardiac surgery. Patients were included in one of three groups: Group A-patients in sinus rhythm with normal left ventricular function undergoing coronary artery bypass grafting, Group B-patients in sinus rhythm with MR undergoing mitral valve surgery, or Group C-patients in persistent AF with MR undergoing mitral valve surgery. Conduction patterns, regional conduction velocity, conduction heterogeneity, conduction anisotropy, and complex fractionated atrial electrograms (CFAEs) were assessed. Results: LA diameter was greater in patients in Groups C (57 ± 4mm) and B (54 ± 6mm) than in Group A (39 ± 7mm, P <0.01). Patients in Group C had a greater number of lines of conduction delay than Groups A and B (2.0 ± 0.8 vs 1 ± 0 and 1 ± 0, P <0.05). The extent of conduction delay and conduction heterogeneity was greater in Group C than in Group B, which was greater than in Group A (P <0.05). The percentage of CFAEs that remained stable during AF was 61% ± 17%. There was a significant correlation between CFAEs during AF and regions of slow conduction during pacing (R = 0.36, P <0.001). Conclusion: Patients with MR, LA enlargement, and AF have more extensive regions of conduction slowing in the posterior LA. Anatomically constant lines of conduction delay in this region lead to circuitous wavefront propagation. During persistent AF, fractionated electrograms in the posterior LA are distributed to regions demonstrating slow conduction, and the majority remain stable over time.

Original languageEnglish
Pages (from-to)1109-1117
Number of pages9
JournalHeart Rhythm
Volume6
Issue number8
DOIs
Publication statusPublished or Issued - Aug 2009

Keywords

  • Atrial fibrillation
  • Atrial stretch
  • Conduction delay
  • Mitral regurgitation
  • Posterior left atrium

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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