Abstract 13879: Are Complex Fractionated Atrial Electrograms Related to Fibrosis or Fiber Orientation?
Introduction: Complex fractionated atrial electrograms (CFAE) recorded during atrial fibrillation (AF) have been described as a target for ablation. It is unknown if CFAE are functional or are related to fibrosis or fiber disarray in the underlying left atrial substrate. We used a canine rapid atrial pacing model of AF to test the hypothesis that regions of CFAE would have more fibrosis and fiber disarray compared to non-CFE regions.
Methods: Five canines underwent rapid atrial pacing at 440 ppm for 10–12 weeks to establish persistent AF; two control animals without pacing were also included. A left atrial geometry and contact bipolar fractionation map of the left atrium (LA) was acquired. Regions of stable CFAE (fractionation interval <120ms for 1 minute) were identified. After sacrifice, the CFAE and non-CFAE regions were outlined on the atrium and sections were examined for the presence of fibrosis (graded 0 to 4+, Masson's trichrome stain) and changes in myofiber orientation.
Results: There was a mild increase in global left atrial fibrosis in the AF animals compared to nonpaced controls (median 1+ vs. 0). Stable CFAE regions at the LA roof (n=1) or posterior wall (n=4) were identified and compared to 5 non-CFE regions on the anterior wall near the mitral annulus. There was no difference in degree of fibrosis (median 1+ vs. 1+) or fiber orientation between CFE and non-CFE regions (Figure, fibrosis=blue).
Conclusions: CFAE are primarily functional, and may be related to activation wavefronts from overlapping left atrial structures on the posterior wall or septum. In this first histologic analysis of CFAE regions, we found no evidence of increased fibrosis or fiber disarray in CFAE compared to non-CFAE regions in the canine AF model.
- © 2010 by American Heart Association, Inc.