Novel morphological classification of left atrial appendage using 3-dimensional printer -rock, paper and scissors-
Authors: Ryuzaki S , Kondo Y , Nakano M , Nakano M , Kajiyama T , Ito R , Chiba T , Yoshino Y , Komai Y , Takanashi Y , Kobayashi Y 
Published: October 2024

Abstract

Background
The WATCHMAN device was developed as a permanent implantable device to seal off the LAA to prevent cardiogenic embolism. It has been used in Japan since September 2019 only for patients who are at the high risk of bleeding events. It is known that the LAA diameter of Asians is larger than that of non-Asians. Furthermore, the LAA of the Japanese are more complicated, compared to the Western. Whereas the four classifications from previous reports are widely used in the world, the classification differs with different physicians in the real-world practice.

Purpose
We aimed to identify the relationship between morphological features of LAA and clinical events such as ischemic stroke in Japanese patients.

Methods
All LAAC cases in our institution performed between February 2020 and December 2023 were retrospectively analyzed. The three-dimensional printing of LAA was generated from cardiovascular computed tomography imaging data. The shapes of the LAA were classified into 3 morphological types: (1) The LAA with bi lobe was defined as "Scissors" type; (2) The one with complicated peripheral branches was "Paper" type; (3) The simple one was "Rock" type. We examined the between the risk of cardioembolic stroke and the morphological features of the LAA.
The left atrial appendage was classified by two cardiologists, and when they made different choices, we used the operator's choice.

Results
The cohort consisted of 116 patients, excluding 22 patients without CT scans. Of those, 30 (26%), 38 (33%) and 48 (41%) patients were divided into the Rock, Scissors and Paper types, respectively. All groups were identically matched for comorbidities. Table shows the patient characteristics and the results of univariate and multivariate analysis. There were 51 (44%) patients who had a history of cardioembolic stroke (18% vs. 30% vs. 53%; Rock vs. Scissors vs. Paper types, p-value = 0.05). In the multivariate analysis, the Paper type is the potential risk factor of cardioembolic stroke (p-value = 0.01). In addition, of those, 36 (31%), 32 (28%), 28 (24%) and 20 (17%) patients were divided into the Chicken wing, Cactus, Cauliflower and Windsock types, respectively. The four types were not associated with prior cardioembolic stroke events (18% vs. 25% vs. 55%; Chicken wing vs. Cactus vs. Cauliflower vs. Windsock types, p-value = 0.83). The match rate of cardiologists’ choice was 86.2% for the new classification and 44.8% for the classical classification.

Conclusions
The morphological features of LAA by three-dimensional printing was significantly related to cardioembolic stroke in this population. Patients with Paper type LAA were significantly more likely to have had a history of cardioembolic stroke. These results could have a relevant impact on the antithrombotic management of patients who are at the high risk of embolic and bleeding events and, moreover, LAAC could be the best option for these patients.