Pranav Bhagirath

103 Left atrial sphericity: a promising parameter to predict response to ablation Limitations The percentage of LASP is obtained after segmentation of the LA cavity. Although the segmentation process is mostly automated, the sub-classification of the PV’s and LAA is performed manually and is therefore susceptible to inter-observer variations. The impact of manual sub-classification has been evaluated by Bisbal et al. (12) . Their results showed a high concordance correlation coefficient of 0.96 and 0.94 for intra- and inter-observer variability. These results indicate that despite the manual nature of the segmentation process, it is a highly reproducible and clinically applicable technique. The sample size of 25 patients is a lower limit for statistical evaluation. However, the purpose of the study was to indicate the feasibility of using left atrial geometrical remodeling as a predictor of repeat ablation success (proof of concept). To this extent, the current sample size is considered sufficient. Future perspectives The study results indicate that geometrical changes of the LA following index ablation, reflected by the LASP, can predict the success rate of a repeat procedure. Comparative studies should further investigate the long-term clinical impact of these results for patient selection and procedural outcome. CONCLUSION Changes in LASP following index PVI can reliably predict the procedural success rate (probability of AF recurrence) for patients undergoing repeat catheter ablation for AF. A reduction of the LASP is strongly correlated with a higher success rate of the repeat procedure. Applying geometrical remodeling as a selection criterion could improve the procedural efficacy of repeat AF ablation.