The US Food and Drug Administration (FDA) has issued a warning letter to iRhythm Technologies over regulatory violations pertaining to its single-use cardiac monitoring chest patch.

The warning, which was issued after an inspection of the company’s facility in Cypress, California, states that the Zio QX ECG Monitoring System lists violations that are further to a Form 483 received by iRhythm in 2022.  

In the warning letter published May 25, concerns were raised around unapproved marketing for critical care patients, making further changes to the device without a new 510(k) submission, and improper labelling.

Moreover, the FDA mentions quality system regulation violations and medical device reporting violations – the latter pertaining to iRhythm belatedly telling FDA about two patient deaths whilst using the device.

In the letter, the FDA told iRhythm “your firm should take prompt action to address any violations identified in this letter. Failure to adequately address this matter may result in regulatory action being initiated by the FDA without further notice.”

iRhthm confirmed receipt via a Form 8-K. The company stated it “takes these matters very seriously” and, in response to the Form 483, has “already taken measures intended to address certain items identified by the FDA”. 

The FDA notice did not include any restrictions on manufacturing, production, or shipment of the device – iRhythm said, unless further action is taken by the FDA, its financial results will not be materially impacted.

At market close on Tuesday June 6, shares were down by 20% in the company from May 24.