Percutaneous left atrial appendage closure with a novel self-modelizing device: A pre-clinical feasibility study
Introduction
Atrial fibrillation (AF) is the most common tachyarrhythmia in clinical practice [1] and can result in thromboembolic events leading to serious illness or even death. Eight to 21% of patients scheduled for a cardioversion attempt present with left atrial thrombi [2], [3]. Over 90% of these thrombi are located in the left atrial appendage (LAA) [4]. Emboli originating from the LAA often cause stroke, associated with a mortality of 38% in 12 months and a 12 month recurrence rate of 17% [5]. The risk of embolization of left atrial thrombi depends on the atrial size, sludge formation, and blood flow velocity in the left atrial appendage, patients' age, risk factor profile, and other factors [6]. The main risk of an embolic event in atrial fibrillation, however, is the lack of adequate anticoagulation [7]. Oral anticoagulation (OAC) is very effective and relevantly reduces the stroke risk by 62% [5].
Patients at high risk of embolic stroke, but with contraindications for OAC are in a need of an alternative approach that is not associated with a long-term risk of hemorrhage or other adverse events. This is particularly necessary for those patients who have survived intracranial hemorrhage but remain at high risk for cardiogenic embolism. A reasonable alternative may be the exclusion of the LAA cavity from circulation, using either surgical or percutaneous catheter-based procedures. Currently, the excision of the LAA at the time of mitral valve surgery is recommended for reduction of future stroke risk [8]. The efficacy of LAA exclusion in patients undergoing elective coronary artery bypass graft surgery was shown in the LAA Occlusion Study (LAAOS) [9].
The frequency of thrombus formation in the LAA of patients with AF and its suspected role as a source of embolism led to the hypothesis that resection or obliteration of the LAA might reduce the risk of stroke. Johnson et al. [10] performed atrial appendectomies in 437 patients during cardiac surgery. They found no strokes that were attributed to AF, and no patients were found to have atrial clots on TEE during follow-up [10]. Nevertheless, surgical LAA closure has not been accepted due to its invasive nature. But, based on the surgical experience, the development of a less invasive percutaneous approach to close the LAA by implantation of a mechanical device was a logical consequence. Since 2001 clinical studies using different systems (PLAATO®, Amplatzer®, Watchman®) were performed [11], [12], [13], [14]. However, these devices have limitations in terms of limited recapture and repositioning capabilities as well as significant leaks after implantation, which increase by time [15].
In the present study the feasibility and safety of the Occlutech® LAA occluder were analyzed in a big animal model study.
Section snippets
Methods
In accordance with the “Position of the American Heart Association on Research Animal Use,” adopted by the AHA on November 11, 1984 and after approval of the study protocol by the Department of Animal Science University of Kaposvár, Hungary at the Test Facility, twelve young pigs were included in the study. The Test Facility is accredited by the Hungarian Government (9/2001.(III.30.) EüM-FVM) and is registered to conduct research in laboratory animals. All the conditions of testing conform to
Results
Details of the implanted devices are shown in Table 1. Two procedure-related complications caused by heart perforations occurred during transseptal puncture due to difficulties in visualizing the atrial septa. One pig died due to tamponade and the other pig had a small pericardial effusion, but recovered fully and had no further complications. These complications depended on difficulties in TEE visualizing the atrial septa due to the anatomy of the pig heart and could not be attributed to the
Discussion
Transcatheter LAA occlusion may be considered in non-valvular atrial fibrillation patients with a high stroke risk and contraindications for long-term oral anticoagulation [16]. The number of implantations of LAA occluders already started to grow markedly and is expected to rise further in the near future. At present, 2 different occluder systems are available, the Watchman® and the Amplatzer® Cardiac Plug device. However, both occluders are still having some limitations [17]. The Watchman®
Conclusion
The study device achieved complete closure of the LAA in all pigs, and remained in the LAA, with benign healing and no evidence of new thrombus or damage to surrounding structures. Moreover, the uncompromised survival of all implanted pigs demonstrates the feasibility and safety of the device.
Funding of the study
The study was funded by the Occlutech, Jena, Germany.
Conflict of interest
Dr. Park is a consultant for Occlutech, Jena, Germany.
References (22)
- et al.
Prognostic implications of left atrial spontaneous echo contrast in nonvalvular atrial fibrillation
J Am Coll Cardiol
(1994) - et al.
Transesophageal echocardiographically facilitated early cardioversion from atrial fibrillation using short-term anticoagulation: final results of a prospective 4.5-year study
J Am Coll Cardiol
(1995) - et al.
Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation
Ann Thorac Surg
(1996) - et al.
Risk scoring and thromboprophylactic treatment of patients with atrial fibrillation with and without access to primary healthcare data: experience from the Stockholm health care system
Int J Cardiol
(2013) - et al.
Sequential changes in renal function and the risk of stroke and death in patients with atrial fibrillation
Int J Cardiol
(2013) - et al.
Alternatives to chronic warfarin therapy for the prevention of stroke in patients with atrial fibrillation
Int J Cardiol
(2011) - et al.
Left Atrial Appendage Occlusion Study (LAAOS): results of a randomized controlled pilot study of left atrial appendage occlusion during coronary bypass surgery in patients at risk for stroke
Am Heart J
(2005) - et al.
Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: a randomised non-inferiority trial
Lancet
(2009) - et al.
Percutaneous left atrial appendage transcatheter occlusion (PLAATO system) to prevent stroke in high-risk patients with non-rheumatic atrial fibrillation: results from the international multi-center feasibility trials
J Am Coll Cardiol
(2005) - et al.
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)
J Am Coll Cardiol
(2013)
Cited by (12)
Foam-based Left Atrial Appendage Closure (CLAAS) Device: Evaluation in a Chronic Canine Model
2023, Journal of the Society for Cardiovascular Angiography and InterventionsRecent developments in next-generation occlusion devices
2021, Acta BiomaterialiaAn overview of current and emerging devices for percutaneous left atrial appendage closure
2019, Trends in Cardiovascular MedicineCitation Excerpt :The delivery sheath is steerable and has the flexibility to bend 180° to adapt to the axis of the LAA. This feature should be useful in case of complex LAA morphologies – e.g., reversed chicken wing – or in cases in which the transseptal puncture is challenging (or suboptimal) [28]. Animal implants with the re-designed Occlutech™ LAA occluder were performed in Q1-2018 and a CE Mark trial is anticipated in 2018–2019, with an expected commercial re-launch by the company in 2020.
Preclinical assessment of a modified Occlutech left atrial appendage closure device in a canine model
2016, International Journal of CardiologyCitation Excerpt :At the end of the study, each animal was anesthetized using isoflurane and was euthanized using an intravenous overdose of potassium. The Occlutech LAA occlusion device (Occlutech®, Jena, Germany) was described previously [7]. Briefly, this device has a self-expanding, flexible, nitinol mesh structure with a cylindrical shape.
Safety and feasibility of left atrial appendage inversion in swine: A proof-of-concept study for potential therapy to prevent embolic stroke
2023, Frontiers in Bioengineering and Biotechnology
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Drs. Park and Sherif have contributed equally to the work.