ISCHEMIC STROKE / STROKE PREVENTION

Left Atrial Appendage Occlusion (LAAO)

Created 14/12/2021, last revision 16/09/2022

  • atrial fibrillation (AFib) is a leading preventable cause of ischemic stroke
  • the risk of stroke in people with AFib can be stratified with prediction instruments, such as  CHA2 DS2–VASc
  • early detection of AFib (especially in its paroxysmal form) and treatment with anticoagulants are critical
  • the anticoagulant therapy has significant bleeding risks and may be contraindicated in certain patients (although the situation has improved with the availability of DOACs)
  • the endovascular or surgical treatment of the left atrial appendage (LAA) has been suggested as an alternative to anticoagulant therapy in high-risk patients
    • because a significant proportion of thrombi in AFib form in the LAA (57% valvular AFib – 91% NVAFib)
  • the method is recommended by the guidelines
    • in patients with stroke or TIA in the setting of NVAF who have contraindications for lifelong anticoagulation but can tolerate at least 45 days, it may be reasonable to consider percutaneous closure of the LAA with the Watchman device to reduce the chance of recurrent stroke and bleeding   (AHA/ASA guidelines 2021 2b/B-R)
    • ESC guidelines 2020 IIb/B
Left atrial appendage (LAA)
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LAA occlusion methods

Endovascular LAAO
  • all percutaneous LAA occluder implantation procedures require peripheral venous access (typically via the right femoral vein)
  • after that, the transseptal puncture is performed to gain access to the left atrium
  • then specific steps for the deployment of individual nitinol occluder devices (Watchmen, Amplatzer, Amulet) are taken
  • in the Lariat procedure, a magnet link is created between an endocardial wire and pericardial wire, followed by epicardial suture ligation of the LAA
  • regardless of the type of the closure procedure, transesophageal echocardiography (TEE) imaging is essential for preprocedural screening, intraprocedural guidance, and postprocedural follow-up

Watchman  Watchman  → see here

  • made of a self-expanding nitinol skeleton and a permeable polyester cover
  • Watchman device has the most available outcomes data
  • FDA approved (2015)

Amplatzer Amulet  (Abbot) → see here  Amplatzer amulet

  • LAA Occluder comprises a lobe and disc connected by a flexible waist and is constructed from a nitinol mesh covered with a polyester patch
  • according to registries, the risk of periprocedural complications is up to 4.8%, the subsequent risk of occluder thrombosis is 1.5-5%   [Mandrola, 2017]

Amplatzer Cardiac Plug  Amplatzer cardiac plug

Lariat system  → see here

  • FDA approved, capable of eliminating even larger LAAs
  • closure with the Lariat device consists of both endocardially and epicardially delivered magnetic tipped wires that unite at the distal LAA wall
  • once adequate ligation of the LAA is confirmed on echocardiography, the endocardial balloon catheter and wire are removed
  • finally, the epicardial suture is released from the snare and tightened, which excludes the LAA
  • high risk of complications was reported (14.7%)!  [Price, 2014]
Lariat system
LAAO - Lariat system
Surgical LAAO
  • surgical LAA occlusion may be performed during concurrent cardiac surgery (ESC guidelines 2020  IIb/C)
  • the benefit is not reliably assessed, positive results with reduced mortality and risk of stroke have been reported  (Yao, 2018)

Periprocedural antithrombotic therapy

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Complications

  • some authors report complications in up 20% of cases  [Fauchier,2018]
    • the incidence of DRT in patients with LAA imaging was 7.2% per year
  • according to the LAAO registry, major periprocedural complications are present in 2.16% of patients [Freeman, 2020]
    • most commonly pericardial effusion requiring intervention was reported (1.39%)
    • stroke (0.17%) and death (0.19%) were rare
  • follow-up TEE may detect incomplete LAA occlusion (leak)
Device-Related Thrombus (DRT)  Device related thrombus (DRT)
  • the annual risk of DRT is:
  • DRT is strongly associated with a higher risk of ischemic stroke during follow-up
  • therefore, after the procedure, temporary antithrombotic treatment is necessary (until the occluder is covered with endothelium)
    • there is no universal antithrombotic protocol, mostly the therapy is derived from trials (see above)
  • main risk factors for DRT according to the LAAO-DRT registry:
    • permanent AFib
    • pericardial effusion (pathological accumulation of fluid in the pericardial sac)
    • hypercoagulable state
    • renal insufficiency (CKD)
    • deep implant position (>10mm from the pulmonary/coumadin ridge – the structure between the left superior pulmonary vein and the LAA) [Freixa, 2021]
      • coumadin ridge has often been misdiagnosed as a thrombus in the past
Incomplete occlusion (leak)
  • human left atrial appendages vary in size and shape
  • according to registries, TEE at 45 days identified three groups of patients:
    • with no leak
    • with small leaks (< 5 mm)
    • with large leaks (≥ 5 mm)
  • a partial occlusion can create a convenient nidus for thrombus (Alkhouli, 2022)
    • small leaks are associated with a modestly higher incidence of thromboembolic and bleeding events
    • large leaks (>5 mm) were not associated with adverse events, although higher proportions of these patients were maintained on anticoagulation
  • newer devices with improved seal might reduce the leaks-associated events
LAAO leaks

Air embolism

Pericardial tamponade

Occluder migration

Risk-benefit of the procedure

  • given the safety profile of DOACs, the risk-benefit of the LAAO is uncertain
  • after the procedure, antiplatelet therapy is often continued, which itself is risky in terms of bleeding risk [Mandrola, 2017]
    • bleeding risk of ASA vs. DOACs is not that much different (see AVVEROES and RE-SPECT ESUS trials)
    • in addition, many thrombi occur outside the LAA (due to diffuse atriopathy), and this risk increases with the number of comorbidities    [Mahajan, 2012]
  • there is also a discussion about a transient use of DOACs after the LAAO without subsequent long-term ASA administration
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