Percutaneous left atrial appendage closure with a novel self-modelizing device: A pre-clinical feasibility study

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Highlights

  • Preclinical feasibility and safety of a new left atrial appendage occluder.

  • Compared to other devices, the Occlutech® device has rounded loops that fix the device at the landing zone.

  • The nitinol body of this occluder is soft resulting in a better adaptation to the LAA wall with complete closure of the LAA.

Abstract

The aim of the study is to evaluate the feasibility and safety of a new left atrial appendage (LAA) occluder.

Twelve pigs were included. In 2 pigs the implantation process failed due to pericardial tamponade in 1 pig and device embolization in the other pig. The placement of the devices was controlled via TEE and fluoroscopy. After 6 weeks of implantation the hearts were explanted.

The devices were found to be easy to deploy and showed a very good adaptation to the LAA tissue. Eight out of 10 pigs had full closure of the LAA directly after implantation.

After six weeks, due to the self-modelizing properties of the device, all pigs had a full closure of the LAA. The macroscopic evaluation of the explanted hearts showed that all devices were securely integrated in LAA tissues.

There was one case of mild pericarditis but no macroscopic signs of inflammation on the device surrounding endocardium. The explantation revealed that device loops had penetrated the LAA tissue in three pigs. However, no signs of bleeding, pericardial effusion, or other damage to the LAA wall could be detected and the pigs were in good condition with normal weight gain and no clinical symptoms.

The Occlutech® LAA occluder 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.

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)

Cited by (12)

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  • An overview of current and emerging devices for percutaneous left atrial appendage closure

    2019, Trends in Cardiovascular Medicine
    Citation 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 Cardiology
    Citation 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.

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Drs. Park and Sherif have contributed equally to the work.

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