What is the efficacy of left atrial appendage closure for stroke prevention in patients with atrial fibrillation?

Efficacy of Left Atrial Appendage Closure for Stroke Prevention in Atrial Fibrillation

Left atrial appendage closure (LAAC) is effective for stroke prevention in patients with atrial fibrillation who have contraindications to long-term oral anticoagulation, but it should not be considered as a first-line alternative to anticoagulation therapy for most patients. 1

Evidence for LAAC Efficacy

Randomized Clinical Trials

• Two major randomized clinical trials have evaluated the Watchman device (the most widely studied LAAC device):

  • PROTECT AF trial - Demonstrated non-inferiority to warfarin for the composite endpoint of stroke, systemic embolism, and cardiovascular death 1
  • PREVAIL trial - Met safety endpoints but did not achieve non-inferiority for the primary efficacy endpoint 1, 2

• A meta-analysis of these trials showed:

  • Significantly fewer hemorrhagic strokes in the device group compared to warfarin
  • Initial increase in ischemic strokes in the device group, though the difference was not significant when periprocedural events were excluded 1
  • Long-term follow-up (mean 3.8 years) showed superiority for the primary efficacy endpoint 1

Patient Selection

• Current guidelines recommend LAAC primarily for:
  • Patients at high risk of stroke (CHA₂DS₂-VASc score ≥3) 1
  • Patients who have contraindications to long-term oral anticoagulation 1
  • Patients who can tolerate at least 45 days of post-procedural anticoagulation 1

Limitations and Considerations

Procedural Risks

• LAAC procedures are technically challenging and require specific expertise 1
• Potential complications include:
  • Pericardial effusion
  • Periprocedural stroke
  • Incomplete closure with residual stroke risk 1
  • Device-related thrombus formation

Post-Procedure Antithrombotic Regimen

• Standard protocol in clinical trials:

  • Warfarin for 45 days post-procedure
  • Dual antiplatelet therapy for 6 months
  • Aspirin indefinitely 1

• This requirement limits LAAC use in patients who cannot tolerate any anticoagulation, though some centers are exploring antiplatelet-only regimens 1

Anatomical Considerations

• The LAA is the source of approximately 90% of thrombi in non-valvular AF 3
• However, not all strokes in AF patients are cardioembolic, and the LAA is not the only left atrial region where thrombi can originate 1
• This suggests that some patients may still require antithrombotic therapy even after LAAC 1

Current Guideline Recommendations

• American Heart Association/American Stroke Association (2021): LAAC with the Watchman device may be reasonable for patients with stroke or TIA in the setting of non-valvular AF who have contraindications for lifelong anticoagulation but can tolerate at least 45 days of anticoagulation (Class 2b, Level of Evidence B-R) 1

• European Society of Cardiology (2012): LAAC may provide an alternative for AF patients at high risk for stroke with contraindications to chronic oral anticoagulation, but is not indicated simply as an alternative to anticoagulation therapy 1

Clinical Implementation

• LAAC should be performed within a multidisciplinary team approach involving:

  • Electrophysiologists
  • Interventional cardiologists
  • Neurologists
  • Imaging specialists 1

• Careful patient selection is critical, focusing on those who:

  • Have a high stroke risk (CHA₂DS₂-VASc ≥3)
  • Cannot tolerate long-term oral anticoagulation
  • Can tolerate the periprocedural antithrombotic regimen 1

• Operators should be experienced and properly trained in the specific device and technique to minimize complications 1

Conclusion

While LAAC has shown promise for stroke prevention in AF, oral anticoagulation remains the preferred therapy for most patients with AF and elevated stroke risk. LAAC should be considered primarily for patients who are poor candidates for long-term oral anticoagulation due to bleeding risk or poor medication adherence.