Exploring new dimensions: cardiac tomography advances in left atrial appendage wall thickness assessment

The left atrial appendage (LAA) is a finger-like extension originating from the main body of the left atrium, characterized by a neck and one or multiple lobes. Closure devices for the LAA are typically implanted at the neck level. Peri-device leaks during LAA closure have different causes, and the LAA thickness and stiffness may play a role in them.

This study aimed to assess the feasibility of utilizing a novel software tool, based on cardiac computer tomography (CCT), for measurement of left atrial appendage (LAA) wall thickness.

In fifteen patients, ten with a history of atrial fibrillation undergoing LAA closure (study group) and five without structural heart disease (control group), CCT synchronized with ECG-triggered at 75% of the RR cycle was acquired to capture the maximum volume of the left atrium. Using ADAS 3D software (Adas3D Medical S.L., Barcelona, Spain), LAA was segmented into two structures: neck and lobes. The thickness of the neck was analyzed using a novel tool within the software that allows the measurement of thickness of the left atrium wall and may be applicable also for LAA (figure 1). The thickness is represented using a color-coded system (red <1 mm, yellow 1-2 mm, green 2-3 mm, blue 3-4 mm, violet >4 mm).

Among the 15 patients analyzed, those who underwent LAA closure were significantly older, more hypertensive, and diabetic with a mean history of atrial fibrillation of 7.1 ± 3.2 years. Analyzing a total of 681±177 points per patient, the mean neck wall thickness in the control group was significantly greater than in the group that underwent LAA closure (1.29±0.61 mm vs. 1.18±0.49 mm, p<0.001). (Table 1). Conclusion: Through the use of myocardial thickness quantification software, the feasibility of measuring the left atrial appendage (LAA) wall thickness has been demonstrated. With proof of concept established, further studies with larger sample sizes are needed to determine the clinical implications of LAA wall thickness in optimizing the outcomes of closure procedures.