FDA WARNING_LETTER - iRhythm Technologies, Inc. - August 12, 2022

The FDA issued a Warning Letter to iRhythm Technologies, Inc. on May 25, 2023, following an inspection from July 25 to August 12, 2022. The inspection found significant violations regarding the Zio AT System, a medical device intended for continuous ECG recording and cardiac event reporting.

Key violations include: 1. **Unapproved Device Violations:** The Zio AT System is adulterated and misbranded because iRhythm marketed it for "near real-time monitoring" and "high-risk patients," claims not cleared under its K163512 510(k) for long-term monitoring of non-critical care patients. Additionally, the firm made significant hardware, firmware, and algorithm changes (e.g., to the arrhythmia detection algorithm) without submitting new 510(k)s, which could significantly affect device safety and effectiveness.

2. **Labeling Violations:** The device is misbranded because its labeling lacks adequate directions for use, specifically regarding a transmission limit (100 patient-triggered, 500 auto-detected events). Once reached, data transmission stops, rendering the device unable to perform its intended function for near real-time monitoring. Physicians and patients are not adequately informed about this limit, its implications, or necessary actions.

3. **Quality System Regulation (QSR) Violations (21 CFR