Abstract 11162: Low Left Atrial Appendage Flow Velocity Predicts Treatment Failure in Patients With Left Atrial Thrombi: Insight From the LAT Trial

Abstract

Background: Blood stasis is one of the important pathogeneses in the formation of left atrial (LA) thrombi. The LA appendage peak flow velocity (LAAV) is an established quantitative parameter for estimating the thromboembolic risk. However, it remains unknown whether the LAAV affects the successful resolution of LA thrombi even after prescribing an appropriate oral-anticoagulation treatment. Purpose: To evaluate whether the LAAV is associated with successful resolution of LA thrombi. Methods: The analysis was performed from the LAT trial, a multicenter observational study investigating the outcomes of silent LA thrombi detected by trans-esophageal echocardiography (TEE) or computed tomography. Management of oral anticoagulants was at the physician’s discretion, and resolution of LA thrombi was checked by follow-up TEE. Of 297 patients registered in the trial, we enrolled 236 patients (median age, 69 years; 28% female; 100% atrial fibrillation) whose baseline LAAV data was available in this study. Results: The prescription rates of oral-anticoagulants at baseline and the final follow-up were 83.5% and 93.6%, respectively (p = 0.002). During a median follow-up of 387 (interquartile range, 367-414) days after the thrombi detection, LA thrombi successfully resolved in 145 (61.4%) patients by altering the oral anticoagulants. Patients with resolved LA thrombi had a higher baseline LAAV than those without (28.4 ± 18.5 vs. 19.8 ± 9.3 cm/s, p < 0.001). A receiver operating curve analysis revealed that the best cut-off value for predicting treatment success or failure was 25 cm/s (area under the curve: 0.651, p < 0.001). After adjusting for age, gender, body mass index, heart failure, and warfarin use, an LAAV ≤ 25 cm/s was a significant predictor of failed resolution of LA thrombi (hazard ratio, 1.54; 95% confidence interval, 1.09-2.18; p = 0.015). Conclusions: In the LAT trial, one third of patients failed thrombolysis even 1 year after identifying silent LA thrombi. An LAAV ≤ 25 cm/s at baseline independently predicted treatment failure with oral anticoagulants.