Resolution of silent left atrial thrombi and clinical outcomes in patients with atrial fibrillation: insight from the LAT trial

Abstract Background Silent thrombi in the left atrium (LA), which are thrombi that have not yet caused thromboembolism, are occasionally observed in patients undergoing transesophageal echocardiography (TEE) for atrial fibrillation (AF). However, there is limited data regarding the impact of resolving these silent LA thrombi (LAT) on patient outcomes. Methods We conducted a retrospective review of clinical records from 2010 to 2018 at six hospitals, involving 17,436 TEE procedures for patients with AF. Among these, 297 patients (1.7%) were identified with silent LAT. Of these, 169 patients with follow-up TEE or cardiac computed tomography data for assessing the resolution of LAT were included in this study. The study population were categorized into two groups: the successful resolution group, defined as those with complete LAT resolution without any related events (N=130), and the failed resolution group (N=39). The latter included patients with residual LAT at the last follow-up (N=26), individuals with thromboembolic events (N=8), or those who required surgical intervention for LAT (N=5). Results During the median follow-up period of 394 days (interquartile range, 373-421 days) following thrombi detection, ischemic stroke and systemic thromboembolism (IS/SE) were observed in 10 cases, major bleeding in 23 cases, and all-cause death in 8 cases. In comparison to the successful resolution group, the failed resolution group not only exhibited a higher incidence of IS/SE (1.5% in the successful vs. 20.5% in the failed resolution group, Log-rank p < 0.001) but also showed trends toward increased major bleeding (10% vs. 23.1%, p = 0.033) and higher total mortality rates (3.1% vs. 10.3%, p = 0.05). These differences in composite endpoints were also statistically significant (13.9% vs. 35.9%, p = 0.001). Conclusion In patients with silent LATs were identified, non-resolution of these LATs was associated with not only a higher incidence of IS/SE but also increased rates of major bleeding and all-cause mortality. Conversely, patients who experienced LAT resolution exhibited more preferable prognoses. The status of LAT resolution is closely associated with patient outcomes, underscoring the importance of monitoring LAT resolution in stratifying patient prognoses.