Does Spontaneous Echo Contrast in the Left Atrial Appendage Increase Thromboembolism Risk After Left Atrial Appendage Closure? A Retrospective Study on Its Impact on Device‐Related Thrombosis and Arterial Thromboembolic Events

<b>Background:</b> Left atrial appendage closure (LAAC) prevents arterial thromboembolic events (ATEs) in nonvalvular atrial fibrillation (AF). Spontaneous echo contrast (SEC) is an independent risk factor for left atrial appendage (LAA) thrombosis; however, there is little knowledge about the relationship between preoperative SEC and the increased risk of device-related thrombosis (DRT) or ATEs in patients with AF who have undergone LAAC. <b>Methods:</b> This retrospective study focused on patients with nonvalvular AF who successfully underwent LAAC surgery. Transesophageal echocardiography (TEE) was used to assess preoperative LAA status. SEC in LAA Grades 0-2 was defined as LAASEC-, and Grades 3-4 or previously diagnosed LAA thrombus formation as LAASEC+. <b>Results:</b> A total of 519 AF patients (432 in LAASEC- group and 87 in LAASEC+ group) who underwent LAAC were included. At the 1-year follow-up, there was no significant difference in the incidence of DRT (2.5 vs. 3.8%, <i>p</i> = 0.636), ATEs (0.5 vs. 0%, <i>p</i> = 0.525), and all-cause mortality (2.1% vs. 2.3%, <i>p</i> = 0.899) between the LAASEC- group and the LAASEC+ group. However, the LAASEC+ group had higher proportions of cauliflower-type LAA and ≥ 3 lobes. <b>Conclusions:</b> The difference in preoperative LAA thrombosis or LAASEC was not related to the incidence of DRT or ATEs in AF patients within 1 year after LAAC.