Zoll Medical Corporation, which received FDA clearance a few years ago for both home and hospital versions of its wearable defibrillator LifeVest, is now dealing with a range of lawsuits and FDA actions over problems with the device. At least two people have died because their vests failed to activate due to an electrical problem, the FDA reports, while local media in Pittsburgh reports that other patients are having the opposite problem, with burns and rashes caused by the device activating erroneously.

The FDA first began issuing warnings about the device, prompting a voluntary recall by Zoll, in January of last year. According to Zoll and the FDA, a small portion of vests need to be immediately replaced when they display a service warning, or they might not activate in the event of a heart attack. The company has attempted to address the problem by making the alerts harder to ignore and by ensuring all patients receive training before being issued the device on how to respond to that error message.

The FDA's latest missive came yesterday after a second death was reported, which occurred after the voluntary recall but prior to the software update Zoll is deploying to fix the problem.

"The 'Call for service — Message Code 102' has existed as a service code since the LifeVest 4000 was approved by the FDA in 2009," Zoll said in a letter to healthcare providers earlier this year, before the most recent death. "The unfortunate single death associated with this issue, as referenced in the FDA communication, occurred when a patient did not call Zoll after receiving prompts for 10 consecutive days by the 'Call for Service — Message Code 102' displayed on the device. In response to this rare, but potentially life-threatening situation, Zoll modified the instructions for patients if a 'Call for service — Message Code 102' is displayed on the LifeVest device. All LifeVest patients have received that revised training since September 2017."

Additionally, Pittsburgh's Action News 4, which covers the area where the company's factory is based, reports that the company is facing at least two wrongful death lawsuits related to the above electrical problems, as well as a slew of FDA complaints from patients whose vests went off prematurely, as in the case of an 11-year-old girl whose family says she suffered burns and multiple false alarms from the device.

There's also some question as to the vest's overall effectiveness. A study last summer showed that use of the vests by patients who had previously had a heart attack reduced all-cause mortality but not mortality from sudden cardiac death. Investigators, however, speculated that misclassification of some deaths could be responsible for the odd result.

Zoll Medical declined to be interviewed for this story.