1Universitätsklinikum Jena Klinik für Innere Medizin I - Kardiologie Jena, Deutschland; 2Universitätsklinikum Jena Institut für Diagnostische und Interventionelle Radiologie Jena, Deutschland
Background: Left atrial (LA) thrombus in patients (pts) presenting for LA ablation is an absolute contraindication to ablation. Although thrombi can still form despite the use of oral anticoagulation (OAC) in advance of the procedure. Transesophageal echocardiography (TEE) has been considered the gold standard for LAA thrombus detection. Additional cardiac computer tomography (CT) is often performed in pts with persistent atrial fibrillation (AF) or atrial tachycardia (AT). The aim of the study was in routine workflow 1) to identify the incidence of LAA thrombi in TEE and CT, 2) to search for an association in detecting LAAthrombi in the two methods and 3) to find out if the LAA flow velocity/ LA volume influences the thrombus detection.
Methods: Between 05/2018 and 10/2023 patients with AF/ AT under OAC which were scheduled for a LA ablation were included. TEE and CT searching for LAA thrombus were carried out at intervals of up to 7 days. LAA flow velocity measured in the TEE. A 3-D reconstruction of the LA from the CT was done using EnSite Verismo (Abbott, USA). The LAvolume which included LAA and excluded the pulmonary veins were obtained from the CT at the end- systole.
Results: Patients characteristics (n= 283) included mean age of 66y (+9), 182 male, mean CHA2DS2-VASc score 3 [0-7]. All pts were orally anticoagulated with the majority under NOAC (n= 265). Mean LA volume (LA + LAA) was 158 ml (+45ml),
In 16 pts (6%), a LAA thrombus was detected using TEE. In the TEE of 42 patients (15%),SEC or Sludge was described but no solid thrombus. An LAA thrombus in the CT was described in 27 pts (10%). In 16 pts (6%) the CT was not able to give a definitive diagnosis of the presence of thrombi due to contrast medium recesses or flow phenomena. In 8 out of 35 events (23%) TEE and CT agreed on the diagnosis of a thrombus, in 6 cases during same-day examinations. 15 patients with LAA thrombus described on CT but not on TEE (mean time interval between examinations was 2d). 8 patients with LAA thrombus described on TEE but not on CT (mean time interval between examinations was 1.5 d). In a total of 200 out of 283 pts (71%), CT and TEE were in agreement in excluding a thrombus (p= 0,358).
LAA flow velocity and thrombus verification by TEE showed a significant correlation (p < 0.001). No correlation was found between the presence of a thrombus on CT and LA volume(p= 0.964).
Discussion: In 12% of the patients, all treated with OAC, a thrombus was described in at least one of the examinations or in both. Only in one out of four pts TEE and CT agreed on the diagnosis of a thrombus. It was notable that both examinations excluded thrombi in 70%. LAA flow velocity and thrombus verification in the TEE are significant correlated. LA volume and thrombus notification in CT are not related.
Conclusion: In routine workflow, the diagnosis or exclusion of LAA thrombus is still challenging. The findings regarding thrombus diagnosis were relatively frequently discrepant between the two methods. Even in TEE, the gold standard, the result depends on the physician performing the examination. In contrast to this, the value of the CT is limited by the interaction of flow phenomena and the time of CT- scan.