title: The impact of 6 weeks of atrial fibrillation on left atrial and ventricular structure and function.
abstract: OBJECTIVE
  The impact of prolonged episodes of atrial fibrillation on atrial and ventricular function has been incompletely characterized. The purpose of this study was to investigate the influence of atrial fibrillation on left atrial and ventricular function in a rapid paced porcine model of atrial fibrillation.
  
  
  METHODS
  A control group of pigs (group 1, n = 8) underwent left atrial and left ventricular conductance catheter studies and fibrosis analysis. A second group (group 2, n = 8) received a baseline cardiac magnetic resonance imaging to characterize left atrial and left ventricular function. The atria were rapidly paced into atrial fibrillation for 6 weeks followed by cardioversion and cardiac magnetic resonance imaging.
  
  
  RESULTS
  After 6 weeks of atrial fibrillation, left atrial contractility defined by atrial end-systolic pressure-volume relationship slope was significantly lower in group 2 than in group 1 (1.1 ± 0.5 vs 1.7 ± 1.0; P = .041), whereas compliance from the end-diastolic pressure-volume relationship was unchanged (1.5 ± 0.9 vs 1.6 ± 1.3; P = .733). Compared with baseline, atrial fibrillation resulted in a significantly higher contribution of left atrial reservoir volume to stroke volume (32% vs 17%; P = .005) and lower left atrial booster pump volume contribution to stroke volume (19% vs 28%; P = .029). Atrial fibrillation also significantly increased maximum left atrial volume (206 ± 41 mL vs 90 ± 21 mL; P < .001). Left atrial fibrosis in group 2 was significantly higher than in group 1. Atrial fibrillation decreased left ventricular ejection fraction (29% ± 9% vs 58 ± 8%; P < .001), but left ventricular stroke volume was unchanged.
  
  
  CONCLUSIONS
  In a chronic model of atrial fibrillation, the left atrium demonstrated significant structural remodeling and decreased contractility. These data suggest that early intervention in patients with persistent atrial fibrillation might mitigate against adverse atrial and ventricular structural remodeling.
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo.
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Kazui
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo.
authors.forename: Mathew C
authors.initials: MC
authors.lastname: Henn
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Watanabe
authors.affiliation: Cardiovascular Division, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo.
authors.forename: Sándor J
authors.initials: SJ
authors.lastname: Kovács
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Lawrance
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Greenberg
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo.
authors.forename: Marc
authors.initials: M
authors.lastname: Moon
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Schuessler
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, Mo. Electronic address: damianor@wustl.edu.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Damiano
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology*; D004195:Disease Models, Animal; D006325:Heart Atria / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D013552:Swine; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*
keywords: Cox-Maze; atrial fibrillation; atrial function