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

Medical Device Problem Code	Patient-Device Incompatibility (2682)
Health Effect - Clinical Code	Hypersensitivity/Allergic reaction (1907)
Date of Event	04/16/2026
Type of Reportable Event	Serious Injury
Additional Manufacturer Narrative
A review of the complaint revealed that the patient wore the zio at for only a few hours of the prescribed wear period.The patient does have sensitive skin and does have history of reactions to medical adhesive.The exact cause of the reported event cannot be determined; however, the patient¿s preexisting allergy cannot be ruled out as a contributory factor.Skin irritation and allergic reaction is a known inherent risk of the device.The device manual warnings section read as follows: do not use the zio at patch on patients with known allergic reaction to adhesives or hydrogels or with family history of adhesive skin allergies.Patient may experience skin irritation.If skin irritation such as severe redness, itching or allergic symptoms develop, remove the zio at patch from the patient¿s chest.This event is being reported per 21cfr803 as a serious injury.This report does not constitute an admission by rhythm 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 presented to the emergency room (er) with skin irritation allegedly caused by the zio at.The patient¿s son reported that the patient developed a rash at the application site.The device was subsequently removed.While in the er, the patient was evaluated by a healthcare provider (hcp), who diagnosed an allergic reaction and prescribed an unspecified topical cream for treatment.

• 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: 25128641
• Report Number: 3007208829-2026-00178
• Device Sequence Number: 10737643
• Product Code: QYX
• UDI-Device Identifier: 00869770000210
• UDI-Public: (01)00869770000210(17)260801
• Combination Product (Y/N): N
• 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: Consumer
• Initial Reporter Occupation: Non-Healthcare Professional
• Type of Report: Initial
• Report Date (Section B): 05/08/2026

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: Lay User/Patient
• Device Expiration Date: 08/01/2026
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 04/30/2026
• Type of Report(Section G): Thirty-Day
• Initial Date Received by Manufacturer: 04/20/2026
• Initial Report FDA Received Date: 05/08/2026
• Was Device Evaluated by Manufacturer? (Y/N): Yes
• Date Device Manufactured: 02/02/2026
• 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: 55 YR
• Patient Sex: Female