Late discovery of left atrial appendage occluder device embolization: a case report

Background Left atrial appendage (LAA) closure has been well evaluated in the prevention of stroke in patients with atrial fibrillation. Device embolization remains one of the most common complications. To the best of our knowledge, there have been no reports of late discovery of LAA occluder device embolization at 1.5 years after implantation. Case presentation We describe the case of a 77-year-old man who underwent uneventful LAA closure. Echocardiography performed the next day showed the device in place. The patient was discharged but was then lost to follow-up. 1.5 years later, he was admitted for ischemic stroke. Transesophageal echocardiography showed the absence of the occluder device in the LAA. Computed tomography scan of the abdomen showed the device in the abdominal aorta. Due to the high cardiovascular risk, the device was kept in place and the patient was treated medically. Conclusions Per-procedural and late device embolization are not uncommon. Review of the literature however showed no report of late discovery of device embolization at 1.5 years. Follow-up echocardiography is mandatory for the detection of endothelialization or embolization.


Background
Several studies have evaluated different left atrial appendage (LAA) occluder devices and demonstrated noninferiority in stroke prevention compared to warfarin in patients with atrial fibrillation (AF) [1,2]. Early device embolization remains one of the most common complications, which requires urgent extraction. We herein describe a case of late discovery of an occluder device embolization that was not extracted but rather medically managed.

Case presentation
A 77-year-old male patient with a medical history significant for permanent AF with a CHA 2 DS 2 -VASC score of 6, ischemic stroke with residual seizure and two hemorrhagic strokes, was referred for LAA closure using a Watchman device (Boston Scientific, Inc., Natick, Massachusetts). LAA morphology and measurements were obtained from cardiac computed tomography (CT) angiography and transesophageal echocardiography (TEE). LAA was bilobed. The maximum width of the ostium was measured at 20 mm. Hence, a 24 mm device was successfully implanted. The device was well aligned with the axis of the LAA. A gentle tug test did not change the device position. The patient remained stable and there were no complications noted during or after the procedure. Transthoracic echocardiography (TTE) performed the next day showed the device in place. The patient was discharged with a scheduled TEE six weeks after the procedure but was lost to follow-up.
1.5 years later, he presented with two new ischemic strokes and unexplained left foot pain. Repeat TTE/TEE showed the absence of the occluder device in the LAA. CT scan of the chest and abdomen showed the device in the abdominal aorta between the ostium of the celiac trunk and the superior mesenteric artery (Fig. 1, Panels A-C). Mild thrombosis was seen in the device at the level of the fabric membrane (Panels B and D). The abdominal aorta was severely calcified (Panels A and C). Due to the high cardiovascular risk, surgical or percutaneous extraction were not done and the device was kept in place. Low dose aspirin was added to his medical treatment. The patient died 3 months later from seizure.

Discussion and conclusions
Complications of Watchman device implantation are rare, with device embolization rates of 0.6 and 0.7% [1,2]. Device extraction can be performed either percutaneously via a snare introduced in the femoral artery sheath (e.g., for Watchman device), or surgically (for larger devices) [3]. Percutaneous removal remains the treatment of choice for vascular embolization, particularly in patients with multiple comorbidities and the elderly population. Device embolization risk depends on the operator's experience, the choice of device size and the final position. Patient related characteristics such as LAA morphology and length, ostium size or unusual morphologies are also important criteria. Per procedural TEE guidance is mandatory, thereby avoiding vigorous tug testing (usually performed for proof of device stability). Nevertheless, aggressive physical movements are not advised before endothelialization [4].
Published articles retrieved from PubMed database included single center/multicenter registries, randomized controlled trials, observational studies, case reports and a systematic review   (Table 1). Device embolization occurred mostly during the procedure and within 7 days in the described cases. Some cases reported embolization at 45 and 48 days [3,16,19]. A study published by Swaans et al. [5] described device embolization 3 months following the procedure. Another case described percutaneous retrieval of an AMPLATZER cardiac plug 6 months after embolization [23]. In a systematic review, Aminian et al. [24] concluded that embolization occurred mostly in the periprocedural period but late embolization was not uncommon. Review of the literature however showed no report of late discovery of device embolization at 1.5 years. Since in the majority of cases device embolization is asymptomatic, patient education for short and long term follow-up is extremely important as there is no way to know the exact timing of device embolization. Hence, in our case, embolization could have occurred earlier but was lately picked up due to loss of follow-up.
We report a unique case of late discovery of LAA occluder device embolization in the abdominal aorta. Per procedural and follow-up echocardiography is crucial for the detection of device endothelialization or embolization.

Acknowledgments
This article was also published as an abstract in EP Europace [25].
Authors' contributions MJM collected the data and drafted the manuscript, CB reviewed the literature and contributed in data interpretation, RD and MG revised the manuscript, AN took care of the patient and contributed in the conception and design of the manuscript, and JM extensively revised the manuscript and was the main investigator. All authors read and approved the final manuscript.

Funding
Not applicable.
Availability of data and materials Not applicable.
Ethics approval and consent to participate Not applicable.

Consent for publication
Patient's next-of-kin gave written consent for their relatives personal or clinical details along with any identifying images to be published in this manuscript.

Competing interests
Professor Jacques Mansourati is consultant and receives research fees from Boston Scientific and Abbott Laboratories. All other authors declare that they have no competing interests.