MAUDE Adverse Event Report: IRHYTHM TECHNOLOGIES, INC ZIO AT; DETECTOR AND ALARM, ARRHYTHMIA

Medical Device Problem Code	Failure to Transmit Record (1521)
Health Effect - Clinical Code	Unspecified Heart Problem (4454)
Date of Event	03/16/2026
Type of Reportable Event	Malfunction
Additional Manufacturer Narrative
A review of the complaint indicated that on day 2, customer care contacted the patient after a transmission had not been received for a 24-hour period.Troubleshooting activities were performed and confirmed that the patch was functioning as intended.During the interaction, the gateway was observed to have poor connectivity; however, connectivity appeared to be restored during the call.Customer care advised the patient to continue wearing the device based on the information available at that time.The zio at device was subsequently returned to irhythm, and the clinical data were downloaded.Review of the clinical data confirmed that the patient wore the zio at device for the full 14-day prescribed wear period.During preparation of the final report, irhythm identified an arrhythmia that met medical doctor notification (mdn) criteria but had not been transmitted during the wear period.The healthcare provider was notified on day 28.This event is being reported per 21cfr 803 as a product problem /malfunction.This report does not constitute an admission by irhythm that the product described in this report has any defects or has malfunctioned.These terms are included in form fda 3500a and are fixed terms for selection created by the fda to categorize the type of event solely for the purpose of regulatory reporting.
Event or Problem Description
The patient experienced an arrhythmia that met medical doctor notification (mdn) criteria; however, the event was not transmitted during the wear period.The investigation determined that the gateway prematurely stopped transmitting new data.The healthcare provider (hcp) was notified of the patient¿s arrhythmia.No delays in patient treatment were reported, and no adverse events, including death or serious injury, are known to have occurred.

• Brand Name: ZIO AT
• Common Device Name: DETECTOR AND ALARM, ARRHYTHMIA
• Manufacturer (Section D): IRHYTHM TECHNOLOGIES, INC; 699 8th st suite 600; san francisco CA 94103
• Manufacturer (Section G): IRHYTHM TECHNOLOGIES, INC; 6550 katella avenue, suite 200; cypress CA 90630
• Manufacturer Contact: tara mackinnon ; 699 8th st suite 600; san francisco, CA 94103 ; 6094600577
• MDR Report Key: 24980561
• Report Number: 3007208829-2026-00164
• Device Sequence Number: 9698392
• Product Code: QYX
• UDI-Device Identifier: 00869770000210
• UDI-Public: (01)00869770000210(17)260704
• Combination Product (Y/N): N
• Initial Reporter State: CA
• Initial Reporter Country: US
• PMA/510(K) Number: K240117
• Number of Events Summarized: 1
• Summary Report (Y/N): N
• Serviced by Third Party (Y/N): N
• Reporter Type: Manufacturer
• Report Source: Company Representative
• Initial Reporter Occupation: Non-Healthcare Professional
• Type of Report: Initial
• Report Date (Section B): 04/24/2026

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: No
• Is this a Product Problem Report?: Yes
• Operator of Device: Lay User/Patient
• Device Expiration Date: 07/04/2026
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 03/24/2026
• Type of Report(Section G): Thirty-Day
• Initial Date Received by Manufacturer: 03/27/2026
• Initial Report FDA Received Date: 04/24/2026
• Was Device Evaluated by Manufacturer? (Y/N): Yes
• Date Device Manufactured: 04/05/2026
• 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
• Patient Age: 39 YR
• Patient Sex: Female