What does the percutaneous Watchman left atrial appendage closure procedure involve for a patient with non‑valvular atrial fibrillation who is unsuitable for long‑term oral anticoagulation?

What is the Watchman Device Procedure and What Does It Entail

The Watchman device is a percutaneous left atrial appendage (LAA) closure device implanted via transseptal catheterization to prevent stroke in patients with non-valvular atrial fibrillation who have contraindications to long-term oral anticoagulation. 1

Mechanism and Rationale

The left atrial appendage is the source of approximately 90% of thrombi in patients with non-valvular atrial fibrillation, making it the primary target for mechanical stroke prevention strategies. 2, 3 The Watchman device physically occludes this appendage to prevent thrombus formation and subsequent embolic stroke. 3

Patient Selection Criteria

Patients must meet specific criteria before being considered for the Watchman device:

• High stroke risk: CHA₂DS₂-VASc score ≥2 or ≥3 (CMS requires CHADS₂ score ≥2 or CHA₂DS₂-VASc score ≥3) 1, 2
• Contraindications to long-term oral anticoagulation (absolute contraindications preferred) 1, 2
• Must be suitable for short-term warfarin therapy (at least 45 days post-procedure) 1, 2
• Cannot be used in patients with valvular atrial fibrillation 3

The 2019 AHA/ACC/HRS guidelines give this a Class IIb recommendation (Level of Evidence B-NR), meaning it "may be considered" but remains a second-line option compared to oral anticoagulation. 1, 2

The Implantation Procedure

Technical Approach

The procedure is performed percutaneously via transseptal catheterization under general anesthesia with transesophageal echocardiography (TEE) and fluoroscopic guidance. 1, 4

Key procedural steps include:

• Femoral venous access is obtained 4
• Transseptal puncture is performed to access the left atrium 1
• The LAA is sized using TEE and angiography 4
• The Watchman device is deployed to completely occlude the LAA orifice 4
• Adequate intraprocedural anticoagulation with intravenous heparin is essential 5
• Device position, stability, and absence of peridevice leak are confirmed before release 5

Success Rates and Complications

The device is successfully deployed in 98.5% of patients, with complete or minimal residual flow achieved in 99.3% of cases. 6 However, serious periprocedural complications occur in approximately 6-7% of cases. 2

The most common serious adverse events include:

• Pericardial effusion requiring drainage (most common complication) 2, 7
• Major bleeding requiring transfusion 6
• Device embolization 7
• Procedure-related ischemic stroke 7
• 30-day mortality rate of 0.7% 6

A significant learning curve exists, with serious pericardial effusions occurring in 7.1% of the first 3 implant patients at each site compared to 4.4% of subsequent patients. 8

Post-Procedural Antithrombotic Management

The standard post-implantation antithrombotic protocol consists of three phases:

Phase 1 (0-45 days)

• Warfarin (target INR 2.0-3.0) plus aspirin 81-162 mg daily 2, 5
• TEE is performed at 45 days to evaluate for device-related thrombus and peridevice leak 5

Phase 2 (45 days to 6 months)

• Dual antiplatelet therapy (DAPT): aspirin plus clopidogrel 2, 5
• This regimen is initiated only if the 45-day TEE shows no device-related thrombus or significant peridevice leak 5

Phase 3 (>6 months)

• Aspirin 81-162 mg daily indefinitely 2, 5
• Another TEE is recommended at 1 year for continued surveillance 5

This creates a clinical paradox: patients receiving the device due to bleeding contraindications are still exposed to bleeding risks from post-procedural antithrombotic therapy that may be equivalent to direct oral anticoagulants. 2, 5

Surveillance Requirements

Mandatory transesophageal echocardiography surveillance is required at specific intervals:

• At 45 days post-implantation to assess for device-related thrombus and peridevice leak before discontinuing warfarin 5
• At 1 year post-implantation for continued surveillance 5

TEE assessment must evaluate:

• Device position and stability 5
• Peridevice leak (any leak, regardless of size, is associated with increased thromboembolism risk) 5
• Device-related thrombus formation 5
• Pericardial effusion 5
• Pulmonary vein obstruction 5
• Mitral valve impingement 5

Device-Related Complications During Follow-Up

Device-related thrombus formation occurs in up to 7.2% per year and is associated with increased ischemic stroke risk. 2, 5

Risk factors for device-related thrombus include:

• Non-paroxysmal atrial fibrillation (OR 1.90-2.24) 5
• Renal insufficiency (OR 4.02) 5
• History of TIA or stroke (OR 2.31) 5
• Deep device implantation >10 mm from pulmonary vein limbus (OR 2.41) 5

Peridevice leaks are present in approximately 25% of cases, and any leak is associated with increased risk of thromboembolism. 5, 8

Efficacy Compared to Oral Anticoagulation

The PROTECT-AF and PREVAIL trials demonstrated non-inferiority to warfarin for the composite endpoint of stroke, systemic embolism, and cardiovascular death. 2, 3 At a mean follow-up of 3.8 years, LAA closure was superior to warfarin for the primary efficacy endpoint. 2

Hemorrhagic stroke risk is significantly lower with the Watchman device compared to long-term warfarin (relative risk 0.09; 95% CI 0-0.45). 5

Critical limitation: No randomized trials have compared the Watchman device with direct oral anticoagulants (DOACs), which have better safety profiles than warfarin. 2 This is a major evidence gap, as all trial data compared the device against warfarin, not modern DOACs. 2, 5

Institutional and Operator Requirements

The procedure requires a multidisciplinary team approach with specific institutional capabilities: 1

• Interventional cardiology or electrophysiology expertise 1
• TEE capability and expertise 1
• Cardiac surgery backup for emergent complications 1
• Proper operator training to overcome the significant learning curve 8

Clinical Context and Current Role

Oral anticoagulation remains the preferred first-line therapy for stroke prevention in most patients with atrial fibrillation and elevated stroke risk. 2 The Watchman device serves as a second-line option specifically for patients with absolute contraindications to long-term anticoagulation who can tolerate at least 45 days of post-procedural anticoagulation. 1, 2, 5

The FDA approval specifies that patients must be deemed suitable for anticoagulation and, in particular, a period of periprocedural anticoagulation. 1 Patients unable to take any oral anticoagulation were excluded from the Watchman randomized controlled trials, though there is increasing real-world experience with antiplatelet-only regimens outside the United States. 1