St. Jude warns batteries in up to 350,000 defibrillators worldwide could short circuit and fail

MINNEAPOLIS – St. Jude Medical Inc. said Tuesday that nearly 350,000 of its defibrillators implanted in patients may short-circuit and stop, a malfunction that may have killed two people.

Ten people have fainted and 37 more have reported dizziness after their defibrillators failed to keep their hearts beating in proper rhythm, the company said. At least one of the deaths was in the U.S., it said.

The defect was detected in devices made before May 2015.

The news sent St. Jude Medical stock down 3.5 percent in trading Tuesday, to a close of $78.41. A spokeswoman for the company, headquartered in suburban Minneapolis, said it takes the issue “very seriously” but did not expect a material financial effect.

An implantable defibrillator shocks the heart back into rhythm if it stops beating normally. It needs a powerful battery. St. Jude defibrillators use lithium batteries.

“We have identified a very small risk of premature battery depletion in a very small percentage” of implantable defibrillators, Mark Carlson, the company’s chief medical officer, said via email. “While the risk that this will occur in an individual patient is very small, we are informing physicians about this issue so they can make the best clinical decisions for their patients.”

Shares in Medtronic PLC, another major medical device-maker rooted in Minnesota, also fell, and some investment sites speculated that its heart products may be vulnerable to the same battery problem.

Medtronic declined to comment on its stock movement. A company spokeswoman said Tuesday that all lithium medical device batteries have the potential to fail in the way that St. Jude disclosed, but Medtronic was still evaluating St. Jude’s findings.

“All high-power (defibrillator) devices from all manufacturers use lithium batteries; however we use a different battery” than St. Jude, Medtronic spokeswoman Kathleen Janasz said via email. She said the company routinely monitors the performance of its defibrillators.

St. Jude made the announcement in the hours before the Food and Drug Administration published an alert on the St. Jude device failures. It said the potential for premature battery depletion existed in a wide swath of implantable cardioverter defibrillators, or ICDs, and cardiac resynchronization therapy defibrillators, or CRT-Ds.

St. Jude’s at-risk defibrillator models include various versions of its Fortify, Fortify Assura, Quadra Assura, Quadra Assura MP, Unify, Unify Assura, and Unify Quadra devices.

St. Jude set up a web link where patients can go to see if their devices are affected: https://www.sjm.com/en/patients/arrhythmias/resources-support/battery-advisory