ISCHEMIC STROKE / STROKE PREVENTION

Left Atrial Appendage Occlusion (LAAO)

Created 14/12/2021, last revision 07/11/2023

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

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LAA occlusion methods

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 → see here

Amplatzer Amulet (Abbot) → see here

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%, and the subsequent risk of occluder thrombosis is 1.5-5% [Mandrola, 2017]

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
a high risk of complications was reported (14.7%)! [Price, 2014]

surgical LAA occlusion may be performed during concurrent cardiac surgery (ESC guidelines 2020 IIb/C)
the benefit is not reliably assessed, but positive results with reduced mortality and risk of stroke have been reported (Yao, 2018)

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some authors report complications in up to 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)

the annual risk of DRT is:
- 4-8% [Fauchier,2018]
- 4.1% according to the EWOLUTION registry [Boersma, 2019]
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; the regimen is mostly 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)

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)
partial occlusion can create favorable conditions for thrombosis (Alkhouli, 2022)
- patients with large leaks (>3-5 mm) are usually maintained on anticoagulation (if possible), or a vascular plug may be used
newer devices with improved sealing might reduce leak-related events

Air embolism

Pericardial tamponade

Occluder migration

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