Pranav Bhagirath

93 Left atrial sphericity: a promising parameter to predict response to ablation BACKGROUND Patient selection for catheter ablation of atrial fibrillation (AF) is a challenging task (1) , in particular for repeat ablation procedures (2) . Studies evaluating adverse remodeling of the left atrium (LA), measured using size and function, as a predictor for post ablation AF recurrence have reported conflicting results (3-8) . Although these discrepancies could be due to technique inherent limitations of the imaging modality used, it can also be hypothesized that the use of LA dimensions and volume provides only an indirect and inaccurate reflection of structural (tissue based) remodeling. Recent observations in patients undergoing index AF ablation, emphasize the importance of distinguishing between volumetric and geometrical remodeling (9 10) . Bisbal et al. have observed that volumetric changes are not necessarily related to remodeling of the geometry (11) . Furthermore, they have also reported that patients without AF recurrence are found to have favorable geometrical remodeling when compared to those with recurrence (12) . However, to date there is no description of long-term remodeling effects in the patient group with recurrence of AF, especially with regard to their impact on the efficacy of a repeat ablation procedure. This study evaluated the impact of LA geometrical and volumetrical remodeling on repeat catheter ablation outcome. To this extent, long-term remodeling was only evaluated in patients with AF recurrence following an index catheter ablation. These parameters were correlated to the outcome of the repeat ablation procedure. METHODS Patient Population A total of 54 patients who had undergone a first repeat catheter ablation for AF between January 2012 and June 2013 were retrospectively screened for inclusion. In total 25 patients with a contrast enhanced computed tomography (CT) examination pre- and post-index ablation were identified and included in the study. The terms pre- and post- ablation are used with respect to the index procedure (supplemental material). The study complied with the declaration of Helsinki and received approval from the local ethical committee and the institutional scientific board.