St. Jude warns of lithium battery issue with some CRM devices

St. Jude Medical ($STJ) is warning of a possible problem with a lithium-based battery used in some of its high-voltage cardiac rhythm management (CRM) devices that could result in a short circuit.

The company said the problem is connected to two deaths out of almost 400,000 patients who have had the devices implanted. There is a risk the batteries used in the devices could produce “lithium clusters” during high-voltage charging in a subset of its ICD and CRT-D devices manufactured before May 23, 2015.

That could, in turn, result in a short circuit and deplete the battery within a day to a few weeks, rendering the device incapable of delivering therapy. Pacemakers produced by the company aren’t affected by this warning because they operate on low-voltage batteries.

“Our highest priority is the safety of patients depending on our life sustaining technology and we are working with regulators and physicians to communicate about this advisory and the resources we are providing to assist with patient management,” the company said in a release.

St. Jude recommends that patients contact their doctors immediately if their high-voltage CRM device issues a vibratory alert that its battery is nearly depleted, although replacing the device is not recommended “unless the physician determines otherwise.”

News of the warning was first reported Monday night in a Twitter post by Muddy Waters. Back in August, Muddy Waters reported on two types of cyberattacks that could target St. Jude Medical’s pacemakers, ICDs and CRTs. Muddy Waters said it was made aware of the risks by MedSec, the cybersecurity firm that discovered them. St. Jude has disputed the allegations.