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

Model Number	M635WU50310
Medical Device Problem Code	Adverse Event Without Identified Device or Use Problem (2993)
Health Effect - Clinical Code	Thrombosis/Thrombus (4440)
Date of Event	02/01/2026
Type of Reportable Event	Serious Injury
Additional Manufacturer Narrative
B3 date of event: event date estimated as 02/01/2026 as the event was reported to have occurred in february 2026.
Event or Problem Description
It was reported thrombosis occurred.A left atrial appendage (laa) closure procedure was performed, and a 31mm watchman flx closure device was implanted on (b)(6) 2022.It was noted that the implant had a slight gutter.The patient was discharged.At a routine follow up transesophageal echocardiography (tee), a device related thrombus (drt) was noted.The patient remained on eliquis at the time but could not tolerate due to bleeding so the dosage was decreased.The thrombus resolved and the patient was taken off eliquis.In (b)(6) 2026, the patient had another routine follow up tee and another drt was noted on the ridge side of the device toward the limbus.The patient was placed back on half dose of eliquis.
Additional Manufacturer Narrative
B3 date of event: event date estimated as (b)(6) 2026 as the event was reported to have occurred in (b)(6) 2026.The device was not returned for analysis as the device remains implanted; therefore, a technical analysis could not be performed.It was confirmed this device met manufacturing specification prior to distribution and there were no manufacturing deviations which could have contributed to the reported event.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
It was reported thrombosis occurred.A left atrial appendage (laa) closure procedure was performed, and a 31mm watchman flx closure device was implanted on (b)(6) 2022.It was noted that the implant had a slight gutter.The patient was discharged.At a routine follow up transesophageal echocardiography (tee), a device related thrombus (drt) was noted.The patient remained on eliquis at the time but could not tolerate due to bleeding so the dosage was decreased.The thrombus resolved and the patient was taken off eliquis.In (b)(6) 2026, the patient had another routine follow up tee and another drt was noted on the ridge side of the device toward the limbus.The patient was placed back on half dose of eliquis.

• 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: 24532358
• Report Number: 2124215-2026-12558
• Device Sequence Number: 21420197
• Product Code: NGV
• UDI-Device Identifier: 08714729860518
• UDI-Public: (01)08714729860518(17)250424(10)29277449
• Combination Product (Y/N): N
• Initial Reporter State: NC
• Initial Reporter Country: US
• PMA/510(K) Number: P130013
• Number of Events Summarized: 1
• Summary Report (Y/N): N
• Device Implanted Year: 2022
• Serviced by Third Party (Y/N): Unknown
• Reporter Type: Manufacturer
• Report Source: Health Professional,Company Representative
• Initial Reporter Occupation: Physician
• Type of Report: Initial,Followup
• Report Date (Section B): 04/07/2026

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 Expiration Date: 04/24/2025
• Device Model Number: M635WU50310
• Device Catalogue Number: M635WU50310
• Device Lot Number: 0029277449
• 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: 02/27/2026
• Supplement Date Received by Manufacturer: 04/02/2026
• Initial Report FDA Received Date: 03/06/2026
• Supplement Report FDA Received Date: 04/07/2026
• Date Device Manufactured: 04/25/2022
• 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: Other
• Patient Age: 71 YR
• Patient Sex: Female