Background: Electric cardioversion of atrial fibrillation (AF) is associated with an increased risk of embolism, with embolic material existing in the heart cavities. The initiation of oral anticoagulation therapy reduces the risk of thromboembolic events. The aims of this study were to evaluate the prevalence of left atrial appendage (LAA) thrombi in non-valvular AF, to compare vitamin K antagonists (VKAs) and non-vitamin K oral anticoagulants (NOACs) with respect to thrombus prevalence, and to evaluate the rate of LAA thrombus persistence on repeat transesophageal echocardiography (TEE) after treatment change.
Methods: We enrolled 160 consecutive AF patients who presented with an AF duration > 48 h and had undergone TEE before cardioversion.
Results: Left atrial appendage thrombus was observed in 12 (7.5%) patients, and spontaneous echo contrast 4 was observed in 19 (11.8%) patients; the incidence was similar between the NOAC and VKA groups (8.9% vs. 3.6% and 12.4% vs. 18.5 %, respectively). Among patients on NOAC, thrombus prevalence was detected in 8.4% of users of rivaroxaban, 8% of users of dabigatran, and 12.5% of users of apixaban.
Conclusions: The LAA thrombus developed in 7.5% of patients despite anticoagulation therapy, demonstrating similar prevalence rates among patients either on NOAC or VKA. Lower mean LAA flow velocity and a history of vascular disease were independent predictors of embolic material in the LAA. It seems that in the case of embolic materials in LAA under NOAC treatment, switching to VKA provides additional clinical benefit to the patients.
Keywords: atrial fibrillation; electric cardioversion; left atrial appendage thrombus; non-vitamin K antagonist oral anticoagulants; transesophageal echocardiography.