Pranav Bhagirath

29 Multimodality imaging for patient evaluation and guidance of catheter ablation for atrial fibrillation Pulmonary vein anatomy evaluation Electrical isolation of the PV at the antrum level has long become the first step in ablative treatment of AF. Both myocardial sleeves (i.e. cardiac muscular fibers extending into the pulmonary veins) as an underlying trigger of AF and the adjacent disperse atrial substrate, surrounding the PV ostiumcontaining triggers and rotors, must be electrically isolated (1) . There is no uniform PV branching pattern and at least 1 accessory PV is present in 26% of the patients (11) . Therefore, detailed anatomical knowledge is desirable prior to the ablation procedure. TEE, CT and CMR can provide this information; however, only CT and CMR provide true 3 dimensional (3D) datasets that can be imported and fused with the EAM. This allows for detailed visualization of the anatomy thereby increasing catheter maneuvers and procedural efficacy (12;13) . CT and CMR have a high level of agreement in assessing PV anatomy and dimensions (10;37) . PROCEDURAL IMAGING Anatomic guidance EAM systems can reconstruct 3D anatomy relative to a reference point and combine it with local electrical information to direct catheter ablation. Fusion of the EAM shell with a 3D anatomic dataset from CMR or CT provides a highly detailed anatomic projection. Besides the obvious benefits of improved visualization and simplified catheter guidance inside the complex LA anatomy, this approach significantly reduces fluoroscopic exposure (14) . Studies comparing ablation procedures using conventional fluoroscopy versus image integration report a lower arrhythmia recurrence rate for the image integration group, 19% image integration vs. 48% fluoroscopy only (12) . Another study showed similar values, 22.6% for EAM with image integration versus 41.7% using electroanatomic system only (13) . Despite the limited number of patients studied, this data demonstrates the importance of EAM combined with 3D imaging. Fusion of these datasets contributes to reduced fluoroscopic exposure and may increase the efficacy of the ablative procedure. MRI guidance Catheterization laboratories are successfully working towards performing ablation in an MR environment (38) .There are still hurdles to be won; catheter and tracking mechanism adjustments to function inaMRI scanner and trainingpersonnel to shift fromfluoroscopy towards the MR suite, meanwhile maintaining cost-efficiency. The transition to an MRI