Pranav Bhagirath

32 Chapter 2 Recent work examining the correlation between the site of ablation and localization of the scar provides information about conduction gaps that could help in guiding redo procedures (9;28;48) . Reports listing an insufficient accuracy in determining these gaps after fusion of the EAM and LGE images (29;49) might have differences in patient selection, imaging protocol and post-processing tools. Technique inherent artifacts due to arrhythmias, motion or partial volume are also likely to play a role. These results show that the amount of ablation induced LA structural remodeling may be used as a marker for procedural outcome. Furthermore, incorporation of 3D LGE sequences could play an important role during follow up examination and for devising patient specific redo ablative strategies. The inability of echocardiography and CT to performatrial tissue characterization, make CMR the preferredmodality for this purpose. DISCUSSION Various non-invasive imaging modalities are currently employed in the treatment strategy of AF. All techniques have their advantages and limitations ( table 1 ), and due to a different gold standard for each step in the workup, a multimodality approach is advocated in the daily practice. Using multiple modalities is neither cost-efficient nor time-effective. An increasing demand for catheter ablation procedures has resulted in electrophysiology Table 1. Comparison of imaging modalities for catheter ablation workup, guidance and evaluation. TTE TEE CT CMR Pre-procedural LA dimension +(*) ++ ++ ++ LA fibrosis + LA geometry + + LAA thrombus + + + PV anatomy + + + Peri-procedural Procedure guidance + + Post-procedural PV stenosis + (**) + + PV flow + Ablation scar + A summary of the elements encountered during the workup and follow up of a patient undergoing ablation. A ‘+’ is given when the concernedmodality can adequately perform the step. *TTE significantly underestimates these parameters. **TEE has difficulties to thoroughly examine all the PV’s and underestimates the severity of obstruction.