Pranav Bhagirath

85 Implementation of a standardized cardiac magnetic resonance based workflow for atrial fibrillation catheter ablation DISCUSSION It is well established that imaging plays an important role in patient selection and procedural guidance of AF ablation procedures [3] . This study investigated the feasibility of using a standardized and integrated CMR based workflow for patient selection and procedural guidance for AF ablation. As the study population also consisted of patients undergoing a redo ablation, special emphasis was placed on examining the usefulness of LGE-CMR for procedural guidance. Themainfindings are as follows: (1) AcomprehensiveCMRprotocol targetedat acquiring relevant information for catheter ablation can be completed in less than 40 minutes; (2) Post-processing of this information can be completed in less than 5 minutes; (3) The ablation sites of the redo procedures correlate well with gaps detected in the scar-maps; and (4) Not all gaps are electrically active and could be considered as bystanders, not involved in the AF recurrence. Clinical utility of the workflow Currently, patient assessment for AF ablation is often performed using multiple modalities. The findings of this study demonstrate the feasibility of the proposed protocol to perform assessment of LAA thrombus and LA geometry using a single CMR examination. This workflow can contribute to a potential reduction of procedural radiation exposure [13] by providing LA anatomical shells that can be quicklymergedwith the EAM for anatomical guidance of the procedure. Finally, the addition of LGE imaging further expands the utility of this workflow. The information about tissue-characteristics can be used to generate scar-maps and could potentially provide patient-specific (targeted) ablation strategies for redo procedures. Correlation between LGE-CMR gaps and electrical reconnection The gaps identified using LGE-CMR demonstrated a high correlation with the invasively measured sites of reconnection. However, not all LGE-CMR gaps showed electrical reconnection. Although previous investigations have mentioned non-conducting gaps [14;15] , no study has yet characterized the temporal electrical course of these gaps. Certain groups of patients develop AF recurrence long after the ablation procedure. Therefore, it may be hypothesized that such electrically dormant gaps may demonstrate reconnection in the long-term. In such case, these gaps should be considered a potential ablation site during the redo-procedure.