The objective of this study is to assess the efficacy and safety different dosage of rivaroxaban application versus dual antiplatelet therapy after successful closure of left atrial appendage using the LAMBRE device.

Transcatheter left atrial appendage occlusion(LAAO) has emerged as an effective alternative for preventing thromboembolic events in patients with nonvalvular atrial fibrillation. The contemporary strategy for post-implantation antithrombotic medication therapy derived from several initial industrialized authoritative researches, demonstrated as 45 days for anticoagulation and prolonged DOAC for 6 months. In spite of the increasing experience of operators and arrival of new technologies, the rates of DRT still maintained. Therefore, whether altered medication therapy post-implantation attracted overwide attention. Nowadays, new oral anticoagulation such as rivaroxaban, dabigatran has evolved empirically and successively has been applied for days-weeks anticoagulation therapy following LAAO ,yet, the specific recommended dosage remained unclear.

Therefore, the objective of the study is to compare the effects of different dosage of rivaroxaban for short-term(12 weeks) anticoagulation therapy versus DAPT for post-LAAO anti-thrombotic therapy.

Inclusion Criteria:

• Successful transcatheter LAAC using LAMBRE with COST criteria met by intra-procedural TEE and LAA angiography;
• Cha2ds2-Vasc2 score≥2 and or Has-bled score≥3(with contraindication or self-refusal to long-term administration of oral anticoagulants);
• Age18-85 years old;
• Life expectancy≥1 year;
• Written informed consent obtained;

Exclusion Criteria:

• • Prior history of cardiac surgery or with need for intervention in limited intervals;
• Intolerant of TEE or with clinical contraindications for TEE
• Detection of LAA/LA thrombus prior to the procedure;
• Anteroposterior diameter of LAA≥60mm according to TTE
• Impairment of renal function: eGFR≤15ml/min and/or creatinine level≥200μmol/L;
• Patients with hepatic disease that is associated with abnormal blood coagulation(cirrhosis: Child Pugh B an C);
• PLT ≤ 50*10^9/L;
• LVEF≤35% and/or NYHA≥IV；
• Allergies or contraindications to antiplatelet or anticoagulation therapy;
• At high risk of major bleedin(such as gastrointestinal ulcer at present or recently, malignant tumor with high risk of hemorrhage, recent brain or spinal injury, recent brain, spinal or ophthalmic surgery, recent intracranial hemorrhage, known or suspected esophageal varices, arteriovenous malformations, angioaneurysms or major intraspinal or intracerebral vascular malformations, et al)
• Patients with requirement for anticoagulation therapy due to other diseases besides atrial fibrillation (such as after mechanical valve replacement, spontaneous or recurrent venous thromboembolism, etc.);
• Occurrence of severe pericardial tamponade, major hemorrhage and other life-threatening complications after left atrial appendage closure;
• Combined with other basic complications necessary to take drugs that may affect the effect of anticoagulation and antithrombotic regimen in this study(such as pyrrole antifungal agent, human acquired immunodeficiency virus (HIV) protease inhibitor, anti arrhythmia drug dronedarone, powerful cytochrome enzyme CYP3A4 inducer including rifampicin, phenytoin sodium, carbamazepine, phenobarbital, and other anticoagulants).
• Enrolled in other clinical studies in progress;
• Researches think that the patient is not suitable to participate in this study.