What is the failure rate of the Watchman (Left Atrial Appendage Closure) procedure for atrial fibrillation (AFib)?

From the Guidelines

The Watchman procedure for atrial fibrillation has a failure rate of around 5-10%, with device-related thrombus formation occurring in roughly 3-5% of cases post-implantation, as reported in the most recent study 1. The failure rate of the Watchman procedure can be attributed to various factors, including incomplete closure of the left atrial appendage, residual leaks, and device-related thrombus formation. According to the 2025 study published in Nature Reviews Cardiology 1, the risk factors for device-related thrombus (DRT) include non-paroxysmal AF, renal insufficiency, hypercoagulable disorders, pericardial effusion, deep device implantation, and older age.

• The study found that low-grade hypoattenuated thickening, which typically represents device healing, poses a low embolic risk, whereas high-grade hypoattenuated thickening requires intensified anticoagulation therapy.
• The WATCHMAN device has been associated with device-related thrombus, deep implantation, LAA diameter, left ventricular dysfunction, and reduced LAA peak emptying velocity.
• The effectiveness of the Watchman in preventing strokes is comparable to warfarin therapy, with studies showing non-inferiority in stroke prevention, as reported in the 2012 study published in the European Heart Journal 1.
• Following the procedure, patients typically require 45 days of warfarin therapy, followed by dual antiplatelet therapy (aspirin plus clopidogrel) for 6 months, and then lifelong aspirin, as stated in the 2012 study 1.
• Success rates have improved over time with technological advancements and increased operator experience, making the Watchman procedure a reliable alternative to long-term anticoagulation for stroke prevention in appropriate atrial fibrillation patients.

From the Research

Failure Rate of Watchman Procedure for AFib

• The Watchman procedure is a left atrial appendage closure device used to prevent stroke in patients with atrial fibrillation (AFib) 2.
• Studies have reported varying failure rates for the Watchman procedure, with some reporting a low overall complication rate of 1.9% 3 and others reporting an adverse event rate of 7.3% 4.
• The most common complications associated with the Watchman procedure include pericardial effusion, bleeding requiring transfusion, and stroke 3, 4.
• A patient-level meta-analysis of two randomized trials found that left atrial appendage closure (LAAC) with the Watchman device resulted in significantly fewer hemorrhagic strokes and nonprocedural bleeding compared to warfarin 5.
• However, the same meta-analysis found that LAAC was associated with more ischemic strokes compared to warfarin 5.

Procedural Adverse Outcomes

• A study using the National Inpatient Sample (NIS) database found that the in-hospital mortality rate for Watchman device implantation was 0.29% 3.
• The same study reported a pericardial effusion rate of 0.68% and a bleeding rate requiring transfusion of 0.1% 3.
• Another study using the MAUDE database found that the overall adverse event rate for Watchman device implantation was 7.3%, with a mortality rate of 0.4% 4.
• The most common adverse events reported in the MAUDE database included pericardial effusion, device embolization, and stroke 4.

Post-Procedure Antithrombotic Therapy

• A study using the LAAO Registry of the National Cardiovascular Data Registry found that the most common discharge antithrombotic strategies after Watchman device implantation included warfarin and aspirin, direct oral anticoagulant (DOAC) and aspirin, and warfarin alone 6.
• The same study found that discharge on warfarin alone or DOAC alone was associated with a lower risk of adverse outcomes compared to warfarin and aspirin 6.