Almost exactly a year after beginning a recall of some of its implantable defibrillator devices that were found to potentially emit electrical pulses below their programmed strength, Medtronic has sent out an even farther-reaching safety alert for a similar issue.
The previous recall encompassed certain versions of Cobalt and Crome implantable cardioverter defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-Ds), about 80,000 of which had been distributed around the world as of last summer’s safety notice. The new recall, meanwhile, covers specific models of a much broader swath of devices, numbering 816,000 around the world, per Medtronic’s May recall notice.
A total of 348,616 of the affected ICDs and CRT-Ds were distributed in the U.S. alone, according to a Tuesday notice from the FDA. They were all sold between October 2017 and June of this year under nearly a dozen product names, including Cobalt and Crome. The regulator has given the recall its most serious rating, Class I, indicating that the affected devices could potentially cause serious injuries or death.
ICDs and CRT-Ds are implanted in the chest to help maintain a normal heart rhythm. They work by monitoring for signs of arrhythmia and, once detected, sending out electric shocks that can either help coordinate the regular beating of the heart—much like a pacemaker—or interrupt a too-fast rhythm to get it back on track.
According to the May notice, however, Medtronic has found that some of its implants may deliver either low-energy shocks or none at all even when they’ve been programmed to deliver high-voltage therapy. The issue has been linked to a software defect in which the built-in Short Circuit Protection feature could be inappropriately activated.
Per Medtronic, the defect is confined only to ICDs and CRT-Ds that were manufactured after 2017 with a glassed feedthrough.
To date, the company has received reports of 28 incidents, 22 injuries and no deaths linked to the issue. As the FDA noted, if an ICD or CRT-D is unable to deliver the correct dose of electrical energy, allowing a dangerous arrhythmia to continue, it could lead to cardiac arrest or death, among other adverse effects. Additionally, if the issue is misinterpreted as a flaw with the device’s leads, doctors may call for the leads or the entire device to be unnecessarily replaced, opening up the opportunity for surgical complications.
Because of that potential for complications, Medtronic isn’t recommending that the devices be replaced as a preventive measure. Instead, the company has suggested that doctors continue remotely monitoring patients as usual to keep an eye out for interruptions in the devices’ therapy.
Plus, because the majority of the reported incidents occurred when the devices were programmed in the AX>B delivered pathway, Medtronic is also recommending that all patients have their implants reconfigured to deliver high-voltage therapy in the B>AX direction.
With that reconfiguration, Medtronic suggested that the risk of the low- or no-energy issue occurring stands at just 0.002% within five years of implantation and 0.005% after nine years.