Pranav Bhagirath

211 General discussion remains publicly available for accessing the image database, uploading segmentations for evaluation and contributing manual segmentations for improving the consensus ground truth on the datasets. Left atrial geometry Preliminary results of left atrial sphericity (LASP) from the previous study showed that all patients undergoing an index procedure had a lower sphericity of 77 ± 4 when compared to 85 ± 3 in patients undergoing a redo ablation. This was associated with a high AF recurrence and was considered indicative of advanced structural remodeling and rate. These findings lead to a study where the impact of LA geometrical remodeling, expressed as sphericity, and maintenance of sinus rhythm after repeat pulmonary vein isolation was investigated. The results showed a strong relation between the pattern of LA geometrical remodeling and the outcome of a repeat ablation procedure. The post-procedural change in the left atrial geometry, calculated as the difference between pre-procedural LASP and post- procedural LASP, was significantly associated with AF recurrence (p<0.001). Patients with AF recurrence following the redo ablation (n=14) showed an increase of the LASP (negative remodeling) after the index procedure. Eleven patients had a reduction of LASP (positive remodeling) after the index ablation and were all free from AF recurrence following the repeat ablation. This association was independent of volumetric remodeling as both pre- and post- index procedural LA volume index demonstrated no correlation with post-procedural AF recurrence. In addition, conventional clinical parameters such as the nature of AF were not correlated with changes in the LASP as both negative and positive geometrical changes were observed in paroxysmal as well as persistent AF patients. Clinical implications A single modality, CMR based imaging workflow was proven clinically feasible, and suitable to perform patient selection and procedural guidance of AF ablation. The results indicate that procedural efficacy of repeat ablation procedure may be improved by: 1. Incorporating LA sphericity as a stratification criteria during AF ablation workup 2. A scar-map guided (patient-specific) ablation strategy for targeted gap ablation