The primary objective of this investigation is to compare the efficacy of two different antithrombotic strategies after percutaneous LAA occlusion with a Watchman device on the prevention of silent cerebral embolism.

BACKGROUND Left atrial appendage intervention is increasingly recognized as an alternative strategy for thromboembolism prophylaxis in AF. Theoretically, a complete occlusion of left atrial appendage may eliminate the possibility of embolism from the appendage. However, residual risk exists due to blood stasis and endothelial dysfunction in the atrial fibrillation state. This may raise an issue that whether we should and how to give the patients after appendage occlusion long-term antithrombotic therapy.

Meanwhile, patients with AF have a high incidence of silent cerebral embolism (SCE), which has similar impact with clinical stroke on cognition function. We hypothesized that the SCE caused by micro embolism may act as part of the residual risk after appendage occlusion, thus, an optimal antithrombotic treatment to decrease the incidence of SCE remains unclear.

AIM OF THIS STUDY The primary objective of this investigation is to compare the efficacy of two different antithrombotic strategies after percutaneous LAA occlusion with a Watchman device on the prevention of SCE. The primary endpoint is incidence of SCE detected by MRI. The secondary endpoints are more than two new SCE detected by MRI, cognition function and composite endpoint of all-cause mortality, clinical thromboembolic events and major bleeding events.

DESIGN This is a randomized, prospective, multicenter design. We aim to include 150 patients 45 days after successful LAAC with WATCHMAN device. Patients are randomized in a 1:1 fashion into two arms: Standard Antiplatelet Therapy and Half-Dose NOAC. Follow-up duration of this study is 12 months. The 1-year routine follow-up strategy included DW-MRI scans performed approximately 90 days, 180 days, and 365 days post-procedure.

Inclusion Criteria:

1. AF patients over 18 years old
2. Patients had undergone left atrial appendage occlusion with WATCHMAN device and confirmed no significant peri-device leak or DRT at the 45-day CT
3. Patients have a history of ischemic thromboembolic events or have CHA2DS2-VASc score ≥3

Exclusion Criteria:

1. Patients with an indication of long-term antiplatelet therapy other than LAAO at the time of enrollment (eg, ACS, Intracranial vascular stenosis≥75%)
2. Absolute contraindications to OAC
3. Absolute contraindications to anti-platelet therapy
4. Contraindications to MR or unwilling to receiving MR
5. Patients with clinical thromboembolicor major bleeding events within 45 days after LAA occlusion