Three-dimensional printer guided new morphological classification of left atrial appendage -rock, paper and scissors-

Abstract

Abstract Background Cardiogenic embolism by left atrial thrombi is one of the most important atrial fibrillation (AF)-related clinical problems. In a previous survey, 91% of nonrheumatic AF-related left atrial thrombi was originated in the left atrial appendage (LAA). 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. The WATCHMAN family is the only left atrial appendage closure (LAAC) device in JAPAN. 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 The LAAC database of our institution was respectively analyzed. All LAAC cases were performed between February 2020 and February 2022. 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 erasing branches was "Paper" type; (3) The simple one was "Rock" type. We retrospectively examined the relationship between the risk of ischemic stroke and the morphological features of the LAA. Results The cohort consisted of 63 consecutive patients (age, 73±8 years; male gender, 73%; BMI, 24±4 kg/m²; the size of WATCHMAN device, 29±42 mm). Of those, 14 (22%), 21 (33%) and 28 (44%) patients were divided into the Scissors, Paper and Rock types, respectively. All groups were identically matched for comorbidities. Table shows the patient characteristics and the results of univariate and multivariate analysis. There were 35 (56%) patients who had a history of ischemic stroke (4 vs. 9 vs. 22; Rock vs. Scissors vs. Paper types, p-value=0.01). In the multivariate analysis, the Paper type is the potential risk factor of ischemic stroke (p-value<0.01, respectively). Conclusions The morphological features of LAA by three-dimensional printing may be related to cardioembolic stroke. Patients with Paper type LAA were significantly more likely to have had a history of ischemic 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.Table 1Table 2