Cardiac MRI for Preprocedural Assessment in Participants with Nonvalvular Atrial Fibrillation Undergoing Left Atrial Appendage Closure

Purpose To evaluate the feasibility of cardiac MRI for preprocedural left atrial appendage closure (LAAC) planning and to compare cardiac MRI- and transesophageal echocardiography (TEE)-derived measurements. Materials and Methods Patients with nonvalvular atrial fibrillation who were suitable candidates for LAAC between October 2019 and July 2023 were included in this prospective single-center study. Participants underwent preprocedural TEE and cardiac MRI for the measurement of LAA ostium diameter and depth at four angles (0°, 45°, 90°, and 135°), and measurements were compared between modalities. Participants were stratified by renal function (chronic kidney disease CKD group: estimated glomerular filtration rate (eGFR, 2; non-CKD group: eGFR, ≥60 mL/min/1.73 m2). A subgroup of participants also underwent cardiac CT angiography (CCTA). LAA dimensions were analyzed using Pearson correlation and Bland-Altman analyses. Results A total of 108 participants were included (mean age, 76.5 years ± 7.8 SD; 77 male; CKD group, n = 79; non-CKD group, n = 29). TEE- and cardiac MRI-derived LAA ostium diameter measurements showed moderate-to-strong correlation (r = 0.530-0.737), regardless of CKD status. LAA depth measurements showed weak-to-moderate correlation between modalities, with systematically lower measurements for TEE. Agreement between cardiac MRI- and TEE-derived measurements across morphology subtypes was poor. Among the 40 participants who also underwent CCTA, cardiac MRI-derived LAA ostium diameter measurements demonstrated strong correlation with CCTA-derived measurements (r = 0.60-0.82), without systematic bias. Conclusion Cardiac MRI is a reliable, contrast material-free alternative to TEE and CCTA for preprocedural LAAC planning, with measurements unaffected by renal function. Keywords: Left Atrial Appendage Closure, Cardiac MRI, Transesophageal Echocardiography, Cardiac CT Angiography, Chronic Kidney Disease University Hospital Medical Information Network Clinical Trials Registry no. UMIN000040200 Supplemental material is available for this article. © RSNA, 2026.