Impact of left atrial appendage occlusion in atrial flow evaluated through 4D flow cardiac magnetic resonance

Abstract Introduction Device-related thrombus (DRT) and peri-device leak constitute significant complications following left atrial appendage occlusion (LAAO), primarily due to its association with strokes and thromboembolic events. Patient-specific fluid simulations have been employed to explore this hypothesis(1). However, these simulations require detailed anatomical and physiological data, rely on certain assumptions when defining boundary conditions, and involve long computational times. Recently, there has been growing interest in the use of 4D flow cardiac magnetic resonance (CMR) imaging for various cardiovascular diseases, owing to its capability to reproduce blood flow. While its role in the LAAO scenario has been evaluated in silico(2), there are no reported cases of its application in patients undergoing LAAO. Purpose Our objective was to evaluate the impact of LAAO in atrial flow through 4D flow CMR. Methods Five patients undergone LAAO were included in the pilot study. A pre- and 90-days post-procedure 4D flow CMR scans were performed. One of the patients was excluded due to suboptimal image quality. To assess the impact of LAAO on atrial flow dynamics, three parameters were evaluated: a) mean velocity, b) stasis velocity ratio, and c) endothelial cell activation potential (ECAP) index — all associated with an elevated risk of thrombus formation(3,4). Results Baseline and procedural characteristics, along with imaging results, are presented in Table 1. Preprocedural 4D flow CMR for all patients revealed low velocities (Figure 1A) and a high ECAP index (Figure 2A) in the left atrial appendage, indicating flow stasis and an elevated risk of thrombus formation. Successful device implantation was performed in all cases, and no periprocedural complications were detected. Postprocedural 4D flow CMR was feasible in all cases, and no artifacts were detected despite the presence of the LAAO device. An objective increase in velocities and a decrease in the ECAP index were observed in all cases following LAAO. No DRT or ischemic events were reported during follow-up. Conclusions Our preliminary study demonstrates that 4D flow CMR provides valuable information on left atrial flow dynamics following the LAAO procedure. Further studies are warranted to evaluate this promising technique.Table 1.Patient characteristicsFigure 1 and 2.Representative example