The present paper analyzes the role of different imaging modalities for left atrial appendage (LAA) assessment and the recommended specific measurements to improve device selection with regard to the Amulet device.

Morphological LAA assessment is one of the pivotal factors to achieve proper LAA sealing and potentially reduce the risk of complications by minimizing manipulation inside the appendage.

Eight experienced physicians in LAAO were asked to contribute in the preparation of a device sizing consensus manuscript after comprehensive assessment of previous published data on LAA imaging/measurement.

LAA morphology is often complex and requires more detailed spatial resolution and 3-dimensional assessments to reduce the risk of mis-sizing. Traditionally, upsizing of devices based upon the largest measured LAA diameters have been used. However, this may lead to oversizing in markedly elliptical appendages. Thus, when 3D imaging modalities are available, utilizing the LAA mean diameters might be a better alternative. Operators should also note the systematic biases in differences in measurements obtained with different imaging modalities, with CT giving the largest measurements, followed by 3D-TEE, and then 2D-TEE and angiography. In fact, for 2D imaging techniques (2D-TEE and angiography), LAA diameters tend to be underestimated, and therefore, LAA largest diameters seem to be still the best option for device sizing. Some specific anatomies such as proximal chicken-wing or conic LAAs may require different measurements and implantations to achieve implant success.

In conclusion, LAA mean diameters might be a better alternative to largest diameters when 3D imaging modalities are available.