PO-03-139 HIGH-RESOLUTION CARDIAC MAGNETIC RESONANCE IMAGING FOR LEFT ATRIAL APPENDAGE SIZING AND THROMBUS EXCLUSION PRIOR TO DEVICE CLOSURE

Abstract

Transesophageal echocardiography and cardiac computed tomography angiography are currently utilized for left atrial appendage closure (LAAC) planning. The advent of high-resolution cardiac magnetic resonance imaging (HR-CMR) now potentially allows for adequate spatial resolution for LAAC planning. This study sought to assess preoperative HR-CMR with software-based sizing vs intraoperative TEE for LAA sizing and thrombus exclusion prior to LAAC. This retrospective study conducted at The Ohio State University Wexner Medical Center included all patients who underwent preoperative HR-CMR and intraoperative TEE for LAAC with Watchman FLX (Boston Scientific, Marlborough, MA) from May to September 2022. For HR-CMR, magnetic resonance angiography (MRA) and late gadolinium enhancement (LGE) sequences were obtained for LAA sizing and thrombus exclusion respectively. A proprietary sizing software (TruPlan, Boston Scientific) was utilized to analyze the MRA sequence to characterize LAA anatomy, predict closure device size, and estimate device compression ratio. HR-CMR was compared to TEE for assessing accuracy of LAA thrombus exclusion, maximum ostial diameter, depth, lobe count, morphology, and accuracy of predicted device size. 16 patients were included, with baseline characteristics notable for 8 (50%) females, age 73 ± 6 years, 30 ± 7 kg/m2 body mass index, 54 ± 8% left ventricular ejection fraction, and 4 ± 2 CHA2DS2-VASc. 15 (94%) cases were successfully completed. There was no significant difference in LAA thrombus exclusion (CMR 14 (88%) vs TEE 16 (100%) cases, p=0.48), maximum ostial diameter (CMR 20.9 ± 4.2 vs TEE 20.6 ± 4.2 mm, p=0.99), depth (CMR 31.1 ± 7.8 vs TEE 26.8 ± 5.6 mm, p=0.09), lobe count (CMR 1.8 ± 0.8 vs TEE 1.4 ± 0.6 lobes, p=0.25), and morphology features (p=0.44). LAA assessments are summarized in Table I. The mean devices deployed per case was 1.1 ± 0.3. In 2 (13%) cases a device downsize was required. 1 case was aborted due to inability to access a very small LAA ostium. On 45-day TEE or CCTA, no peri-device leak ≥5 mm or device-related thrombus were noted. A comparison of standard vs high-resolution contrast-enhanced (CE)-MRA of the LAA is demonstrated in Figure 1. HR-CMR is a viable modality for preoperative LAA sizing and thrombus exclusion with promising results. HR-CMR may provide utility in cases where TEE or CCTA are contraindicated or unavailable.Tabled 1Table IMeasureHR-CMR (N=16)TEE (N=16)P-valueLAA thrombus accurately excluded14 (88%)16 (100%)0.484Minimum LAA ostial diameter (mm)18.0 ± 4.216.6 ± 3.40.335Target LAA ostial diameter (mm)*20.9 ± 4.220.6 ± 4.20.987LAA depth (mm)31.1 ± 7.826.8 ± 5.60.093Number of lobes1.8 ± 0.81.4 ± 0.60.250Morphology0.437Cactus4 (25%)3 (19%)Cauliflower0 (0%)2 (13%)Chicken wing5 (31%)2 (13%)Windsock7 (44%)8 (50%)Other0 (0%)1 (6%)LAA closure device size accurately predicted12 (75%)12 (75%)1.000Values presented as mean ± 1 standard deviation for continuous variables and n (%) for categorical variables. Abbreviations: HR-CMR = high resolution cardiac magnetic resonance imaging, LAA = left atrial appendage, TEE = transesophageal echocardiography. *Based on maximum diameter measured on TEE vs area-derived diameter on HR-CMR. Open table in a new tab