CardioNerds Amit Goyal, Dr. Colin Blumenthal, Dr. Kelly Arps and Dr. Justice Oranefo discuss mechanical stroke prevention in atrial fibrillation with Dr. Christopher Ellis, cardiac electrophysiology lab director and director of the left atrial appendage closure program at Vanderbilt University. There has been a significant increase in the number of patients undergoing left atrial appendage occlusion (LAAO). This trend is expected to continue with current and upcoming clinical data on this topic. In this episode we dive into the rationale behind LAAO and explore several historical facts. We then proceed to the current state of practice including currently available options, appropriate indications, post op care, and potential complications. Notes were drafted by Dr. Justice Oranefo. Audio editing by CardioNerds Academy Intern, student doctor Chelsea Amo Tweneboah.

This CardioNerds Atrial Fibrillation series is a multi-institutional collaboration made possible by contributions of stellar fellow leads and expert faculty from several programs, led by series co-chairs, Dr. Kelly Arps and Dr. Colin Blumenthal.

This series is supported by an educational grant from the Bristol Myers Squibb and Pfizer Alliance. All CardioNerds content is planned, produced, and reviewed solely by CardioNerds.

We have collaborated with VCU Health to provide CME. Claim free CME here!

Disclosures: Dr. Ellis discloses grant or research support from Boston Scientific, Abbott-St Jude, advisor for Atricure and Medtronic.

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1. Surgical or catheter based left atrial appendage occlusion results in mechanical exclusion of the left atrial appendage, which is the most common source of thrombus leading to embolic events in patients with non-rheumatic atrial fibrillation.
   
2. Surgical LAAO should be considered in patients with atrial fibrillation and CHA2DS2VASC score ≥ 2 undergoing cardiac surgery for other indications.
   
3. Endocardial LAAO devices such as WATCHMAN FLX and AMULET are approved for stroke prevention in patients with atrial fibrillation with a CHA2DS2VASC score ≥ 2 and have an appropriate reason to seek a non-drug alternative to anticoagulation therapy.
   
4. Appropriate patient selection and post-operative anticoagulation and imaging strategy are crucial for prevention and management of complications related to LAAO.
   

What are the types of LAAO device?

Left atrial appendage occlusion devices can be divided into epicardial closure and endocardial closure.

Epicardial techniques/devices include surgical ligation, Atriclip, and Lariat. These techniques require pericardial access (either by open thoracotomy or thoracoscopic access). The goals are complete exclusion and ischemic necrosis of the LAA.

LARIAT device

Atriclip device

Endocardial techniques include WATCHMAN FLX and AMULET devices. These techniques require the use of nitinol-based devices which are delivered into the LAA via a transeptal approach. These devices become endothelialized over time resulting in occlusion of the LAA.

AMULET device

WATCHMAN FLX

Who is the ideal candidate for surgical LAAO?

Several studies have evaluated the efficacy of surgical LAA occlusion. The most prominent being the LAOS III trial which randomized 4770 patients with atrial fibrillation and CHA2DS2VASC ≥ 2 undergoing cardiac surgery for other reasons to surgical LAAO vs no LAAO (3,4). The primary outcome of ischemic stroke or systemic embolization occurred in 4.8% of patients in the LAAO group vs 7% of patients in control group over an average follow-up of 3.8 years. Though patients were randomized to LAAO, there was no requirement to stop anticoagulation and this difference was seen despite 75% of patients continuing anticoagulation. Additionally, there was no significant difference in operation time and bleeding complications.

Based on these findings, LAAO should be considered in patients with atrial fibrillation undergoing cardiac surgery for other reasons regardless of the anticipated anticoagulation strategy.

This ability to perform surgical LAAO requires safe access to the pericardial space. For this reason, conditions that create pericardial adhesions (e.g., prior cardiac surgery, chest radiation or trauma, multiple prior ablations) can limit the ability to perform surgical LAAO.

Who is the ideal candidate for endocardial LAAO?

Several  randomized controlled trials and cohort studies have evaluated the utility of both the AMULET and WATCHMAN devices in stroke prevention with the most notable being the PREVAIL, PROTECT AF, and AMULET IDE trials (5,6,7,8,9,10).

Based on the available data, these devices are indicated for stroke prevention in patients with non-valvular atrial fibrillation, a CHA2DS2VASC score ≥ 2 and an appropriate reason to seek a non-drug alternative to anticoagulation therapy. A classic example is a patient with recurrent GI bleeding despite multiple attempts to tolerate anticoagulation. These devices can also be considered in patients with high-risk professions suck as police officers or fire fighters.

Several individual factors also affect the feasibly of endocardial LAAO. A suitable LAA anatomy is necessary for safe device implant (13). Other important considerations are nickel allergy (consider formal allergy testing in patients with suspected nickel allergy), surgical repair of the atrial septum, and severe kyphoscolisis (making adequate transeptal access difficult).

There is no strong data comparing LAAO to DOAC in patients without high bleeding risk, however this question is being studied in 2 ongoing trials, CHAMPION AF (WATCHMAN FLX) and CATALYST (AMULET).

What are the complications of LAAO?

Surgical LAAO is safe and effective when there is complete occlusion of the LAA, however, historically ~ 20-30% are unsuccessful due to incomplete occlusion. More modern surgical techniques including confirmation with intra-operative transesophageal echocardiogram and the Atriclip have demonstrates a higher rate of success. Though the addition of a LAAO has not been shown to add significant time or risk to an already planned cardiac surgery, this requires a patient to already have an indication for surgery and carries the associated risks of that procedure.

Endocardial LAAO has the advantage of being minimally invasive, but procedural complications such as cardiac tamponade, bleeding, and stroke can occur. More recent data has shown a < 1% procedural risk with the WATCHMAN FLX device. Other post procedural complications of endocardial LAAO devices include peridevice leak (~ 10% incidence; leaks ≥ 3mm are associated with an increased risk of stroke) and device related thrombus (DRT; 2-3% incidence). Device embolism is rare but carries potentially devastating consequences (12).

What is the anticipated post operative care following LAAO?

Post operative care with surgical LAAO is predominently dictated by the primary indication for surgery. Due to the high incidence incomplete exclusion, an intra or post-operative TEE is necessary to document complete LAA occlusion. As for anticoagulation, there is no current randomized control trial data that supports using surgical LAAO as an alternative to AC. As previously discussed, a lower incidence of stroke was seen in the LAOS III trial, but this trial specifically studied using surgical LAAO as an adjunct to OAC, not as a replacement.

With endocardial LAAO, appropriate patient and device selection as well as adequate post-operative care is crucial to maximize safety and efficacy. Patients must be able to tolerate some degree of short-term anticoagulation with the goal to safely transition to single anti-platelet therapy while minimizing the risk of stroke and bleeding. This involves OAC for at least 45 days followed by aspirin monotherapy if no DRT or peridevice leak is seen on post-op imaging. DAPT (aspirin and clopidogrel) can be used instead of OAC in the early phase however there is not strong data for this strategy (11). Post-op imaging (TEE or CTA) is required approximately ~45 days, 6 months, and 1 year after the procedure.

In patients who have undergone LAAO, LAA imaging is recommended prior to cardioversion, however, in the absence of DRT or device leaks anticoagulation is not necessary post cardioversion (14,15).

1. Belcher, J.R. & Somerville, W., 1955. Systemic Embolism and Left Auricular Thrombosis in Relation to Mitral Valvotomy. British Medical Journal, 2(4946), pp.1000–1003.
   
2. Blackshear, J.L. & Odell, J.A., 1996. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. The Annals of thoracic surgery, 61(2), pp.755–759.
   
3. Friedman, D.J. et al., 2018. Association Between Left Atrial Appendage Occlusion and Readmission for Thromboembolism Among Patients With Atrial Fibrillation Undergoing Concomitant Cardiac Surgery. JAMA : the journal of the American Medical Association, 319(4), pp.365–374.
   
4. Whitlock, R.P. et al., 2021. Left Atrial Appendage Occlusion during Cardiac Surgery to Prevent Stroke. The New England journal of medicine, 384(22), pp.2081–2091.
   
5. Reddy, V.Y. et al., 2014. Percutaneous Left Atrial Appendage Closure vs Warfarin for Atrial Fibrillation: A Randomized Clinical Trial. JAMA : the journal of the American Medical Association, 312(19), pp.1988–1998.
   
6. Belgaid, D.R. et al., 2016. Prospective randomized evaluation of the watchman left atrial appendage closure device in patients with atrial fibrillation versus long-term warfarin therapy: The PREVAIL trial. International journal of cardiology, 219, pp.177–179.
   
7. Freeman, J.V. et al., 2020. The NCDR Left Atrial Appendage Occlusion Registry. Journal of the American College of Cardiology, 75(13), pp.1503–1518.
   
8. REDDY, V.Y. et al., 2013. Left Atrial Appendage Closure With the Watchman Device in Patients With a Contraindication for Oral Anticoagulation: The ASAP Study (ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology). Journal of the American College of Cardiology, 61(25), pp.2551–2556.
   
9. Holmes DR Jr, Kar S, Price MJ, et al. Prospective randomized evaluation of the Watchman Left Atrial Appendage Closure device in patients with atrial fibrillation versus long-term warfarin therapy: the PREVAIL trial [published correction appears in J Am Coll Cardiol. 2014 Sep 16;64(11):1186]. J Am Coll Cardiol. 2014;64(1):1-12. doi:10.1016/j.jacc.2014.04.029 
   
10. Lakkireddy D, Thaler D, Ellis CR, et al. Amplatzer Amulet Left Atrial Appendage Occluder Versus Watchman Device for Stroke Prophylaxis (Amulet IDE): A Randomized, Controlled Trial. Circulation. 2021;144(19):1543-1552. doi:10.1161/CIRCULATIONAHA.121.057063
    
11. Magdi M, Renjithal SLM, Mubasher M, et al. The WATCHMAN device and post-implantation anticoagulation management. A review of key studies and the risk of device-related thrombosis. Am J Cardiovasc Dis. 2021;11(6):714-722. Published 2021 Dec 15.
    
12. Della Rocca DG, Magnocavallo M, Gianni C, et al. Procedural and short-term follow-up outcomes of Amplatzer Amulet occluder versus Watchman FLX device: A meta-analysis. Heart Rhythm. 2022;19(6):1017-1018. doi:10.1016/j.hrthm.2022.02.007
    
13. Maan A, Heist EK. Left Atrial Appendage Anatomy: Implications for Endocardial Catheter-based Device Closure. J Innov Card Rhythm Manag. 2020;11(7):4179-4186. Published 2020 Jul 15. doi:10.19102/icrm.2020.110704
    
14. Maarse M, Wintgens LIS, Ponomarenko A, et al. Impact of anticoagulation strategy after left atrial appendage occlusion in patients requiring direct current cardioversion. J Cardiovasc Electrophysiol. 2021;32(3):737-744. doi:10.1111/jce.14889
    
15. Sharma SP, Turagam MK, Gopinathannair R, et al. Direct Current Cardioversion of Atrial Fibrillation in Patients With Left Atrial Appendage Occlusion Devices. J Am Coll Cardiol. 2019;74(18):2267-2274. doi:10.1016/j.jacc.2019.08.1045