The report is a product of the VA/HSR Evidence Synthesis Program.

The Effectiveness of Procedures to Remove or Occlude the Left Atrial Appendage: Systematic Review

Currently, low-strength evidence limited to one device suggests that percutaneous left atrial appendage (LAA) exclusion is associated with a similar risk of long-term stroke and mortality to that of oral anticoagulation, according to a recent systematic review conducted by the Portland Evidence-based Synthesis Program (ESP) Center at the Portland VA Health Care System. However, there are a variety of available devices and the effectiveness of most has not been well studied. Furthermore, the report notes that in many studies percutaneous LAA exclusion has been associated with high rates of serious procedure-related harms. The authors found insufficient evidence to determine the efficacy of surgical LAA exclusion in reducing stroke.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting between 2.7 and 6.1 million people in the United States. The prevalence of AF increases with age and is often associated with structural heart disease and co-morbidities that are common in the Veteran population. AF is the most important cause of cardioembolic stroke, which accounts for 14-36% of all ischemic strokes. While patients at highest risk for AF-related stroke also often have other independent risk factors, most cardiac sources of embolism are thought to be due to thrombus formation from blood stasis in the left atrium. Among patients with non-valvular AF, more than 90% of thrombi develop in the left atrial appendage. Antithrombotic therapy with aspirin, warfarin, or one of several newer oral anticoagulants reduces the risk of stroke due to both atrial fibrillation and atherosclerotic disease, but is associated with a risk of serious bleeding. As a potential alternative to long-term anticoagulant therapy, various LAA exclusion procedures have been developed in an attempt to isolate the LAA from circulating blood flow. These procedures include both surgical occlusion and removal of the LAA and percutaneous catheter-based interventions.

Dr. Alaa Shalaby, a member of the VHA Cardiology Field Advisory Committee and Director of Cardiac Electrophysiology at the VA Pittsburgh Healthcare System, nominated the topic. The purpose of the ESP report was to systematically review the literature to better understand the balance of benefits and harms of surgical or percutaneous LAA exclusion procedures. Dr. William Gunnar, National Director of Surgery for the Veterans Health Administration, also served as an operational partner.

The report found low-strength evidence that percutaneous LAA exclusion is associated with a similar risk of long-term stroke and mortality as continued oral anticoagulation therapy. This finding is based on trials of one device (Watchman) studied in patients without contraindications to oral anticoagulant therapy. However, there is moderate-strength evidence that, in many studies, a substantial proportion (1.6-13.6%) of patients undergoing various percutaneous LAA exclusion procedures experienced serious periprocedural harms. The authors found insufficient evidence to determine whether factors such as operator experience, patient selection criteria, or choice of device can modify these risks. There is insufficient data to assess the balance of benefits and harms of percutaneous LAA exclusion procedures in patients who are ineligible for long-term oral anticoagulation therapy.

Trials of surgical LAA interventions were few and limited by sample size. The report notes that several studies that should add substantively to this body of evidence are underway, including a large RCT of surgical interventions with an estimated sample size of 4,700 patients, studies of recently developed percutaneous devices (LAmbre and Occlutech), and a trial comparing Watchman with Apixaban in patients ineligible for warfarin therapy.

Overall, the report found limited evidence that percutaneous LAA exclusion using the Watchman device may be an effective alternative to long-term oral anticoagulation in selected patients who are closely followed and in whom procedural success is sustained. However, evidence to support widespread use is tempered by the lack of data examining other devices and high rates of procedure-related harms. While surgical LAA exclusion does not appear to be associated with a significant increase in harms over the heart surgery during which the procedures are typically performed, rates of procedural success may be low. Report authors state there is insufficient evidence to support the routine use of surgical LAA exclusion to reduce stroke risk or future need for anticoagulant therapy.

Reference
Noelck N, Papak J, Freeman M, Paynter R, Low A, Motu'apuaka M, Kondo K, Kansagara D. The Effectiveness of Procedures to Remove or Occlude the Left Atrial Appendage: A Systematic Review of the Evidence. VA ESP Project #05-225; 2015.

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This report is a product of VA/HSR&D's Quality Enhancement Research Initiative's (QUERI) Evidence-Based Synthesis Program (ESP), which was established to provide timely and accurate synthesis of targeted healthcare topics of particular importance to VA managers and policymakers – and to disseminate these reports throughout VA.

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