The Safety and Efficacy of Standard-Dose versus Low-Dose Non-Vitamin K Antagonist Oral Anticoagulants in Patients with Nonvalvular Atrial Fibrillation and Left Atrial Appendage Thrombus

Background. Data comparing different doses of non-vitamin K antagonist oral anticoagulants (NOACs) regarding resolution of left atrial appendage thrombus (LAAT) in patients with nonvalvular atrial fibrillation (AF) are scarce. This study aimed to investigate the safety and efficacy of standard-dose versus low-dose NOACs in patients with nonvalvular AF and LAAT. Methods. Patients with nonvalvular AF who underwent transesophageal echocardiography (TEE) before interventional procedures for the detection of LAAT and treated with NOACs from October 2014 to September 2020 in Ningbo First Hospital were retrospectively screened. The study population was divided into two groups according to the doses of NOACs: standard-dose group (dabigatran 150 mg, twice daily; rivaroxaban 20 mg, once daily) and low-dose group (aged ≥75 years, body weight <50 kg, or creatinine clearance <50 mL/min; dabigatran 110 mg, twice daily; rivaroxaban 15 mg, once daily). Repeated TEE was performed 1, 2, and 3 months later. The rate of LAAT completely resolved and incidence of thromboembolic and major bleeding events were compared between the two groups. Results. A total of 24 patients were included, 14 patients in the standard-dose group and 10 in the low-dose group. After 3 months, LAAT was completely resolved in 12 out of 14 (85.7%) and 8 out of 10 (80%) patients treated with standard- and low-dose NOACs, respectively. The rate of LAAT completely resolved was comparable between groups. No thromboembolic or major bleeding events occurred during the follow-up. Conclusion. Low-dose NOACs are a safe and effective option for the treatment of LAAT in some special subset patients. However, the results warrant validation in a prospective study.

Efficiency of the Left Atrial Appendage Thrombus Dissolution in Patients with Persistent Nonvalvular Atrial Fibrillation with Warfarin or Direct Oral Anticoagulants Therapy

Aim. Compare the incidence of the left atrial appendage (LAA) thrombus dissolution in patients with persistent nonvalvular atrial fibrillation receiving warfarin and direct oral anticoagulants (DOAC).Materials and methods. 68 patients with persistent nonvalvular atrial fibrillation were included in a retrospective study (age was 59.7±9.8 years, 60.3% men), in whom at least one repeated transesophageal echocardiographic examination was performed after detecting a thrombus. After detecting a thrombus in the LAA, 37 (54.4%) patients started or continued taking warfarin in doses that ensure the INR maintenance at the level of 2-3, 14 (20.6%) started or continued taking dabigatran at a dose of 150 mg 2 times/day, 14 (20.6%) started or continued taking rivaroxaban 20 mg 1 time/day and 3 (4.4%) started or continued taking apixaban 5 mg 2 times/day. Repeated transesophageal echocardiographic examination was performed on average 33.3±14.2 days after the first one.Results. Dissolution of a previously identified thrombus was found in 26 (83.9%) of 31 patients receiving DOAC and in 19 (51.4%) of 37 patients receiving warfarin (p=0.011). The logistic regression analysis showed that the chances of a thrombus dissolution in LAA while taking DOAC are 14.8 times (95% confidence interval [CI] was 2.469-88.72) higher than while taking warfarin. The size and the rate at which blood is expelled from the LAA also have an independent influence on the chances of thrombus dissolution. An increase in the size of a thrombus by 1 mm reduces the chances of a thrombus dissolution by 1.136 (95% CI was 1.040-1.244) times, and an increase in the rate of blood expulsion from the LAA by 1 cm/sec increases these chances by 1.105 (95% CI was 1.003-1.219) times.Conclusion. In the present study, the incidence of the LAA thrombus dissolution in patients with persistent nonvalvular atrial fibrillation while receiving DOAC was higher than while receiving warfarin.

A Case of Massive Left Atrial Thrombus

Rheumatic heart disease is the most common cause of mitral valve stenosis. Left atrial appendage thrombus is associated with mitral stenosis, but in rare cases the thrombus can extend to the left atrial cavity. We present a case of a severe rheumatic mitral stenosis and associated large left atrial thrombus, with embolic sequelae.