WATCHMAN device for LAA: safety, efficacy confirmed in patients not using OACs

  • Boersma LV & al.
  • Circ Arrhythm Electrophysiol
  • 1 Apr 2019

  • International Clinical Digest
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  • Left atrial appendage (LAA) occlusion with WATCHMAN (Boston Scientific) leads to lower mortality and thromboembolism rates in patients for whom oral anticoagulation (OAC) is contraindicated.
  • Editorial finds results encouraging, notes that ASAP-TOO and STROKE-CLOSE will investigate LAA closure in this population.

Why this matters

  • Recent meta-analysis of PROTECT-AF and PREVAIL found WATCHMAN noninferior to vitamin K antagonists (VKA) for stroke prevention, with lower nonprocedural bleeding and mortality. 
  • Patients with OAC contraindication were not included in those trials.

Study design

  • Prospective multinational nonrandomized 2-year real-world EWOLUTION cohort study (n=1020).
  • Participants had nonvalvular Afib and were at high stroke risk; 72% ineligible for OAC.
  • Outcomes: mortality, bleeding, stroke/transient ischemic attack (TIA)/systemic embolism (SE).
  • Funding: Boston Scientific Corporation.

Key results

  • Dual antiplatelet therapy and OAC discontinued in 85%.
  • Deaths: 161 (16.4%; 95% CI, 13.8%-19.3%), mostly noncardiovascular.
  • Nonprocedural major bleeding: 
    • 46% relative risk reduction (RRR) vs expected rates with VKA.
    • Large RRR in higher-risk subgroups.
  • Ischemic stroke/TIA/SE: 
    • 80% RRR vs predicted by CHA2DS2-VASc.
    • Large RRR in higher-risk subgroups.
  • Device-related thrombus: 34 of 835 (4.1%) receiving routine LAA imaging; none had subsequent stroke/TIA/SE.


  • Nonrandomized; no controls.
  • OAC contraindications unclear.

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