Abstract 2864: Regional Differences in Left Atrial Wall Thickness in Patients With Atrial Fibrillation
Introduction: Successful catheter ablation of atrial fibrillation (AF) requires the creation of transmural lesions in the left atrium (LA). LA wall thickness is thus relevant both for procedural efficacy (the creation of transmural lesions in thick regions) and safety (prevention of perforation in thin regions). This study sought to evaluate regional LA wall thickness in patients with AF.
Methods: LA muscular wall thickness (excluding fat) was measured by 64 slice cardiac computed tomography (CT) in 60 patients with persistent AF prior to catheter ablation procedures. Measurements were performed in all patients at 11 distinct LA locations, including 3 at the roof (right, middle left), 3 at the floor (right, middle, left), 4 at the posterior wall (right, middle, middle-superior, left) and 1 at the origin of the mitral isthmus.
Results: There was a large range of LA wall thickness (average thickness 1.87±0.37 mm, range 0.7–3.3 mm). There was no significant correlation between overall LA size and average wall thickness. There were significant regional differences in LA wall thickness, however (figure⇓). In particular, the LA roof was significantly thicker than the posterior wall and floor (p<0.001), and the mitral isthmus was also significantly thicker than the posterior wall (p<0.001) and floor (p<0.001).
Conclusions: In patients with persistent AF, there is inter- and intra-patient variability in the thickness of the LA muscular wall. In most patients however, the roof and mitral isthmus are thicker compared to the posterior wall and floor.