Features of Left Atrial Appendage Thrombosis in Patients With Persistent Nonvalvular Atrial Fibrillation After COVID-19

Aim To evaluate the incidence and characteristic features of left atrial appendage (LAA) thrombosis in patients with persistent nonvalvular atrial fibrillation (AF) after COVID-19.Material and methods Transesophageal echocardiography (TEE) was performed for 469 patients (57.4 % males; mean age, 64.0 [58.0; 70.0] years) with persistent nonvalvular AF before scheduled sinus rhythm restoration. In 131 of these patients (27.9 %), the most recent episode of arrhythmia developed during the coronavirus infection. The time from the onset of COVID-19 to TEE was 145 [62; 303] days. All patients received an adequate anticoagulant therapy, in most cases, with direct oral anticoagulants for at least 3 weeks preceding the study.Results A LAA thrombus was detected in 20 (5.9 %) patients who have had no coronavirus infection and in 19 (14.5 %) patients after COVID-19 (р=0.0045). 18 of 19 (94.7 %) thrombi found in patients who have had COVID-19 were mural whereas only 5 (25.0 %) of such thrombi were found in patients who have had no COVID-19 (p<0.0001). In the absence of LAA thrombus, the LAA emptying velocity was 32.0 [25.0; 40.0] cm/sec whereas in the presence of a mural thrombus, it was 25.0 [20.0; 32.3] cm/sec, and in the presence of a typical thrombus, it was 17.0 [13.5; 20.0] cm/sec (р<0.0001). A Kaplan-Meier analysis showed that the median time of mural thrombus dissolution was 35.0 (95 % confidence interval (CI), 24.0-55.0) days and for a typical thrombus, this time was 69.0 (95 % CI, 41.0-180.0) days (р=0.0018).Conclusion Patients with persistent AF who have had COVID-19 had LAA thrombosis 2,5 times more frequently and, in most cases, the thrombus was mural. Mural thrombi, in contrast to typical, are not associated with a pronounced decrease in LAA emptying velocity and dissolve twice as fast as typical thrombi with an adequate anticoagulant treatment.