What are the indications for the Watchman device in patients with non-valvular atrial fibrillation (AF)?

Watchman Device Indications

The Watchman device may be considered for percutaneous left atrial appendage occlusion in patients with non-valvular atrial fibrillation at increased risk of stroke (CHA₂DS₂-VASc score ≥2-3) who have absolute contraindications to long-term oral anticoagulation. 1

Primary Indication

The core indication is narrow and specific:

• Patients with non-valvular AF (excluding moderate-to-severe mitral stenosis or mechanical heart valves) 1
• Elevated stroke risk: CHA₂DS₂-VASc score ≥2 (FDA) or ≥3 (CMS criteria) 1, 2
• Absolute contraindications to long-term oral anticoagulation due to bleeding propensity, poor drug tolerance, or adherence issues 1, 2

Oral anticoagulation remains the preferred first-line therapy for stroke prevention in most AF patients with elevated stroke risk. 1, 2 The Watchman is explicitly positioned as a second-line alternative when anticoagulation cannot be sustained long-term. 2

Critical Eligibility Requirements

Must Be Suitable for Short-Term Anticoagulation

A crucial but often overlooked requirement: patients must be deemed suitable for at least 45 days of periprocedural anticoagulation (warfarin or DOAC). 1, 2 This creates a clinical paradox—patients receiving the device due to bleeding contraindications must still tolerate short-term anticoagulation. 2

The original PROTECT AF and PREVAIL trials excluded patients unable to take any oral anticoagulation. 1 However, real-world experience outside the United States increasingly uses antiplatelet-only regimens in truly anticoagulation-ineligible patients, though this remains investigational. 1

FDA vs. CMS Approval Differences

Important regulatory nuances exist:

• FDA approval: Restricted to patients suitable for long-term warfarin but with appropriate rationale to seek a non-pharmacological alternative 1
• CMS approval: Device is an option for patients suitable for short-term warfarin but deemed unable to take long-term oral anticoagulation 1

The CMS language more accurately reflects real-world practice patterns. 1

Evidence Base and Limitations

Comparative Efficacy

The device demonstrated non-inferiority to warfarin in combined analysis of PROTECT AF and PREVAIL trials:

• Significantly fewer hemorrhagic strokes compared to warfarin 1, 2
• Initial increase in ischemic strokes in the device group, but this difference became non-significant when periprocedural events were excluded 1
• Lower cardiovascular death compared to warfarin 2

Critical Evidence Gap

No randomized trials compare the Watchman device with direct oral anticoagulants (DOACs), which have superior safety profiles to warfarin. 2 This represents a major limitation since DOACs are now standard anticoagulation therapy. All device trials used warfarin as the comparator, making the evidence less applicable to contemporary practice. 2

Recent retrospective data suggests the Watchman may have lower rates of major bleeding, TIAs, and ischemic strokes compared to DOACs in high-risk populations, but this requires prospective validation. 3

Procedural Risks to Consider

Serious periprocedural complications occur in approximately 6-7% of cases, including: 2

• Pericardial effusion requiring drainage
• Device embolization
• Major bleeding
• Procedure-related ischemic stroke

Device-related thrombus formation occurs in up to 7.2% per year and is associated with increased ischemic stroke risk during follow-up. 2 Risk factors include: 4

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

Post-Implantation Requirements

Mandatory Antithrombotic Regimen

Standard three-phase protocol: 2

1. Phase 1 (0-45 days): Warfarin (INR 2.0-3.0) plus aspirin
2. Phase 2 (45 days to 6 months): Dual antiplatelet therapy (aspirin plus clopidogrel)
3. Phase 3 (>6 months): Aspirin monotherapy indefinitely

Real-world practice varies, with some centers using DOACs or DAPT alone during the initial period, though this deviates from FDA-approved protocols. 2

Mandatory Surveillance

Transesophageal echocardiography (TEE) must be performed at 45 days and 1 year to evaluate for: 4

• Device-related thrombus
• Peridevice leak (any leak increases thromboembolism risk)

TEE provides superior visualization compared to transthoracic echocardiography for detecting small thrombi and leaks. 4

Clinical Decision Algorithm

Step 1: Confirm non-valvular AF with CHA₂DS₂-VASc score ≥2-3 1

Step 2: Attempt oral anticoagulation (DOAC preferred over warfarin) 2, 5

Step 3: If absolute contraindication to all long-term oral anticoagulants exists, assess suitability for at least 45 days of periprocedural anticoagulation 1, 2

Step 4: If suitable for short-term anticoagulation, consider Watchman with understanding of 6-7% serious complication risk 2

Step 5: If unsuitable for any anticoagulation, consider enrollment in investigational trials using antiplatelet-only regimens 1

Common Pitfalls

• Overuse in patients who could tolerate DOACs: The device should not be used simply for patient preference or convenience when long-term anticoagulation is feasible 1, 2
• Inadequate assessment of short-term anticoagulation tolerance: Patients must be able to complete the 45-day warfarin/DOAC course 1, 2
• Failure to perform mandatory TEE surveillance: Missing the 45-day and 1-year TEE assessments can result in undetected device thrombus or significant leaks 4
• Assuming equivalence to DOACs: No head-to-head trial data exists comparing the device to modern anticoagulation 2