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

Copyright © 2009 Heart Rhythm SocietyBackgroundThe posterior left atrium (LA) is involved in the initiation and maintenance of atrial fibrillation (AF).ObjectiveThe purpose of this study was to compare conduction patterns on the posterior LA in patients with mitral regurgitation (MR), with and without AF.MethodsEpicardial 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.ResultsLA diameter was greater in patients in Groups C (57 +/- 4mm) and B (54 +/- 6mm) than in Group A (39 +/- 7 mm, P ConclusionPatients 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.Kurt C. Roberts-Thomson, Irene Stevenson, Peter M. Kistler, Haris M. Haqqani, Steven J. Spence, John C. Goldblatt, Prashanthan Sanders and Jonathan M. Kalma