MAUDE Adverse Event Report: BOSTON SCIENTIFIC CORPORATION WATCHMAN FLX?; SYSTEM, APPENDAGE CLOSURE, LEFT ATRIAL

Model Number	M635WU50350
Medical Device Problem Code	Adverse Event Without Identified Device or Use Problem (2993)
Health Effect - Clinical Code	Thrombosis/Thrombus (4440)
Date of Event	06/07/2025
Type of Reportable Event	Serious Injury
Additional Manufacturer Narrative
B3 date of event - article publish date used as event date is unknown.Detailed product information was not provided to bsc.We completed a good faith effort to obtain the information.Because the product is unknown at this time, we are unable to provide the complete udi and other product specific information.If additional details become available, a supplemental report will be submitted.Literature citation: abed, m., bechmann, e., fukui, m., & bapat, v.N.(2025).Giant thrombus on the face of watchman flx device.Annals of thoracic surgery short reports.Https://doi.Org/10.1016/j.Atssr.2025.05.014.
Event or Problem Description
Reported via literature article.It was reported that there was a device related thrombus.A left atrial appendage (laa) closure procedure was being performed.A watchman access system (was) and a 35mm watchman flx laa closure device & delivery system (wds) were selected to be used.The procedure was successfully completed with the closure device implanted in the laa of the patient.There were no patient complications that were reported to have occurred.The patient was discharged on apixaban, but it was discontinued due to recurrent nosebleeds, and they continued on low-dose aspirin.The patient came in two (2) years post procedure, and an imaging procedure was performed.The transesophageal echocardiogram (tee) imaging showed that there was a device related thrombus present on the closure device.Computed tomographic imaging demonstrated a large mobile hypoattenuated cylindrical shaped mass visualized in the left atrium with attachment to the closure device in the left atrial appendage.The distal portion of the mass abuts the atrial aspect of the anterior leaflet of the mitral valve.The closure device was well seated with no evidence of peridevice leak.After multidisciplinary discussion, the patient underwent surgical removal of the left atrial thrombus and exclusion of the closure device using a bovine patch with smooth side facing the atrium and the rough side towards the closure device.The postoperative course was uneventful.
Additional Manufacturer Narrative
B3 date of event - article publish date used as event date is unknown.Detailed product information was not provided to bsc.We completed a good faith effort to obtain the information.Because the product is unknown at this time, we are unable to provide the complete udi and other product specific information.If additional details become available, a supplemental report will be submitted.Literature citation: abed, m., bechmann, e., fukui, m., & bapat, v.N.(2025).Giant thrombus on the face of watchman flx device.Annals of thoracic surgery short reports.Https://doi.Org/10.1016/j.Atssr.2025.05.014.The device was not returned for analysis as the device remains implanted; therefore, a technical analysis could not be performed.Based on a thorough review of the reported complaint, boston scientific has assigned an investigation conclusion code of known inherent risk of device.
Event or Problem Description
Reported via literature article.It was reported that there was a device related thrombus.A left atrial appendage (laa) closure procedure was being performed.A watchman access system (was) and a 35mm watchman flx laa closure device & delivery system (wds) were selected to be used.The procedure was successfully completed with the closure device implanted in the laa of the patient.There were no patient complications that were reported to have occurred.The patient was discharged on apixaban, but it was discontinued due to recurrent nosebleeds, and they continued on low-dose aspirin.The patient came in two (2) years post procedure, and an imaging procedure was performed.The transesophageal echocardiogram (tee) imaging showed that there was a device related thrombus present on the closure device.Computed tomographic imaging demonstrated a large mobile hypoattenuated cylindrical shaped mass visualized in the left atrium with attachment to the closure device in the left atrial appendage.The distal portion of the mass abuts the atrial aspect of the anterior leaflet of the mitral valve.The closure device was well seated with no evidence of peridevice leak.After multidisciplinary discussion, the patient underwent surgical removal of the left atrial thrombus and exclusion of the closure device using a bovine patch with smooth side facing the atrium and the rough side towards the closure device.The postoperative course was uneventful.

• Brand Name: WATCHMAN FLX?
• Common Device Name: SYSTEM, APPENDAGE CLOSURE, LEFT ATRIAL
• Manufacturer (Section D): BOSTON SCIENTIFIC CORPORATION; 300 boston scientific way; marlborough MA 01752
• Manufacturer (Section G): BOSTON SCIENTIFIC CORPORATION; ballybrit business park; galway ; EI
• Manufacturer Contact: rachel shields ; 4100 hamline ave n; arden hills, MN 55112 ; 6512422111
• MDR Report Key: 24315286
• Report Number: 2124215-2026-07753
• Device Sequence Number: 17561848
• Product Code: NGV
• UDI-Device Identifier: 08714729860525
• UDI-Public: (01)08714729860525
• Combination Product (Y/N): N
• Initial Reporter State: MN
• Initial Reporter Country: US
• PMA/510(K) Number: P130013
• Number of Events Summarized: 1
• Summary Report (Y/N): N
• Serviced by Third Party (Y/N): Unknown
• Reporter Type: Manufacturer
• Report Source: Literature,Health Professional
• Initial Reporter Occupation: Physician
• Type of Report: Initial,Followup
• Report Date (Section B): 03/24/2026

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: No
• Operator of Device: Health Professional
• Device Model Number: M635WU50350
• Device Catalogue Number: M635WU50350
• Was Device Available for Evaluation?: No
• Is the Reporter a Health Professional?: Yes
• Type of Report(Section G): Thirty-Day
• Initial Date Received by Manufacturer: 01/30/2026
• Supplement Date Received by Manufacturer: 03/18/2026
• Initial Report FDA Received Date: 02/11/2026
• Supplement Report FDA Received Date: 03/24/2026
• Is the Device Labeled for Single Use? (Y/N): Yes
• Is This a Single-Use Device that was Reprocessed and Reused on a Patient? (Y/N): No
• Usage of Device: Initial
• Patient Sequence Number: 1
• Outcome Attributed to Adverse Event: Required Intervention
• Patient Age: 62 YR
• Patient Sex: Female