Usefulness of a novel sizing chart for left atrial appendage occlusion with the Amplatzer Amulet

Purpose: The present article aims to compare a novel sizing chart based on both maximum and minimum diameters (novel MATRIX) with the current sizing recommendation instructions for use (IFU) based on the maximum diameter.

Background: Current IFU with the Amulet device are still based on the maximum left atrial appendage (LAA) diameter, which might lead to inappropriate oversizing, especially in elliptic appendages.

Methods: This was a retrospective analysis of patients undergoing LAA occlusion in two high-volume centers. Two hundred patients were included (100 patients with baseline cardiac computed tomography angiography [CCTA] and 100 with baseline 2D and 3D-transesophageal echocardiography [TEE]). The degree of concordance between the predicted device size recommendation and the actual device selection was the primary outcome.

Results: The novel MATRIX showed a higher level of concordance between the predicted and implanted device size, regardless of imaging modalities. CCTA showed the strongest, and 2D-TEE the weakest concordance between the predicted and implanted device for both MATRIX and IFU charts. The percentage of patients in whom the disagreement among the predicted and implanted device represented >1 size was higher when using the IFU chart. In elliptical LAA anatomies, the differences favoring the use of MATRIX compared to the IFU in terms of predicted/implanted agreement were higher. Finally, no significant differences in clinical or imaging endpoints were observed between the two different sizing charts.

Conclusions: Incorporating both the LAA maximum and minimum diameters, as opposed to just maximum diameter, appears to improve sizing accuracy. The proposed MATRIX sizing chart offered a higher level of concordance between predicted and implanted device compared to the current IFU.