PO-03-140 CARDIAC MAGNETIC RESONANCE IMAGING VERSUS CARDIAC COMPUTED TOMOGRAPHY ANGIOGRAPHY FOR LEFT ATRIAL APPENDAGE SIZING AND THROMBUS ASSESSMENT PRIOR TO DEVICE CLOSURE

Abstract

Preoperative imaging for left atrial appendage closure (LAAC) is essential for LAA sizing and thrombus assessment. Transesophageal echocardiography (TEE) and cardiac computed tomography angiography (CCTA) have been utilized to date for this purpose. During the recent global iodine contrast shortage, cardiac magnetic resonance imaging (CMR) was utilized as an alternative imaging modality. The purpose of this study was to assess CMR vs CCTA for preoperative LAA sizing and thrombus assessment prior to LAAC. This retrospective study conducted at The Ohio State University Wexner Medical Center included all patients who underwent preoperative CMR or CCTA for LAAC with Watchman FLX or Amplatzer Amulet between May 2022 and October 2022. Primary measures were accuracy of predicted device size, accuracy of thrombus detection/exclusion, and mean difference in maximum LAA ostial diameter and depth as compared to intraoperative TEE. An area-derived diameter approach was utilized with CMR and CCTA to obtain the maximum diameter in order to prevent oversizing highly elliptical ostial shapes. The radius (r) was calculated based on device design. For the octadecagonal Watchman FLX, area = r2 x 3.0782. For the circular Amulet, area = r2 x 3.1416. 75 patients underwent LAAC, and 25 (33%) vs 50 (67%) underwent preoperative CMR vs CCTA respectively. Demographics were notable for age 75 ± 7 years, 32 (43%) females, 31 ± 7 kg/m2 body mass index, 53 ± 9% left ventricular ejection fraction, and 4 ± 1 CHA2DS2-VASc. 64 (88%) and 9 (12%) patients underwent Watchman FLX and Amplatzer Amulet implantation respectively. There was no significant difference with CMR vs CCTA in accuracy of predicted device size (CMR: 16 (64%) vs CCTA: 26 (70%) patients, p=0.604) and accuracy of thrombus assessment (CMR: 22 (88%) vs CCTA: 46 (92%) patients, p=0.680). Among the 57 (76%) cases completed with intraoperative TEE guidance where LAA measurements were obtained, there was no significant difference with CMR vs CCTA in the mean difference in maximum LAA ostial diameter (CMR: 2.9 ± 2.0 vs CCTA: 2.6 ± 2.5 mm, p=0.699) and mean difference in maximum LAA depth (CMR: 9.5 ± 8.5 vs CCTA: 10.8 ± 7.5 mm, p=0.620) as compared to intraoperative TEE. Figure 1 demonstrates LAAC device sizing using multiplanar reconstruction with oblique views of the LAA on CCTA (A-C) and CMR (D-F). CMR and CCTA were comparable for LAA sizing and thrombus assessment prior to LAAC.