After patient death, FDA warns of battery depletion in Medtronic pacemakers

After a patient death, the U.S. Food and Drug Administration is warning about a rare battery-depletion problem in certain Medtronic pacemakers that could cause the devices to quickly lose power and trigger a medical emergency.

The FDA published an alert Tuesday that said Medtronic discovered a problem in which a crack can form in a ceramic electric component in some pacemakers, leading to rapid battery depletion possibly without triggering the replacement indicator. The issue was confirmed in three devices that had been returned to the manufacturer.

The issue could affect two types of devices, including conventional implantable pacemakers that deliver mild electric current to one side of the heart to bring its rhythm back into healthy range. It could also affect cardiac resychronization therapy pacemakers, known as "CRT-P," which pace both sides of the heart to restore a well-organized heartbeat in a patient who has heart failure.

Although the flaw in the devices has a low occurrence rate of 0.0028%, patients with affected devices should get medical help immediately if they feel lightheadedness, dizziness, chest pain, severe shortness of breath or if they lose consciousness.

"These may be signs your device's battery has had a sudden drop or has drained," the alert said.

Medtronic's Azure, Astra, Percepta, Serena and Solara pacemakers are included in the alert.

The full list of model numbers covered by the alert is posted in a performance note on Medtronic's heart-device monitoring page.

Heart devices containing lithium batteries have been the subject of large-scale warnings in the past, including a 2016 recall of 175,000 implantable defibrillators made by St. Jude Medical because of an issue with lithium chemistry that created a short-circuit that drained the battery.

Tuesday's alert with Medtronic pacemakers involves the failure of a component called a capacitor, which can create a short and deplete the battery in a matter of days.

Tuesday's news broke as electrophysiologists from around the nation were gathering in San Francisco for the 40th annual meeting of the Heart Rhythm Society (HRS), whose Twitter account tweeted the news.

Dr. George Crossley, a Tennessee electrophysiologist who has studied device-battery problems and was in San Francisco for HRS, said the rate of failures is very low and patients shouldn't have the devices removed if there's no sign of a problem.

"This is really what we've always called a random component failure," Crossley said, "and not something that in the past would have generated this kind of attention.

"But certainly in the current environment, where we are trying to be as transparent as we can about everything, this is going to get more attention."

However, "it would be a very crazy thing at this point for a patient to want this device removed and replaced. Their chance of getting hurt by getting a device infection with a change-out would be much higher than the chance of their experiencing a failure."

The FDA said Medtronic has sold 131,889 of the devices in the U.S. In its note, Medtronic said it has sold about 266,700 of the devices worldwide.

The issue involves a capacitor that stores electrical energy from the battery.

"While inherently very reliable, a known failure mode of these capacitors is the potential for internal cracking that can be caused by thermal-mechanical stress during manufacturing," the Medtronic performance note says. "Under rare conditions, internal cracking within a capacitor may result in the development of a leakage pathway, causing high current drain and leading to rapid battery depletion. While the issue presents as rapid battery depletion, this is not a battery performance issue."

For newly made devices, the FDA has approved Medtronic's request to use a different capacitor and add a new step in the manufacturing process to better detect component failures.

Tuesday's alert is not classified as a recall, and neither Medtronic nor the agency is specifically recommending anyone have their pacemaker removed.

However, the FDA alert said patients whose pacemakers need to work constantly to keep them conscious and alert — known as "pacemaker-dependent" patients — should carefully monitor their battery life and discuss their options with their doctors.

Patients can check their device ID card or call their physician's office to see if their device is covered by the alert.

Patients should also monitor their device's battery life by using the at-home MyCareLink monitoring system, which sends alerts to doctors and can be monitored via the related smartphone app. The at-home device must be plugged in in order to check the pacemaker's battery level and send reports to a doctor's office.

Once implanted, the pacemakers are designed to last between six and 15 years, depending on the model and pacing settings.

All three confirmed failures happened within the first nine months after implant.

Although the devices may fail without tripping an elective replacement indicator (ERI), the alert says pacemaker-dependent patients who do get an ERI warning should be treated as a medical emergency.

The alert says one of the three reported device failures resulted in the death of a pacemaker-dependent patient.

A second case resulted in a patient who felt dizzy and had their device replaced when the physician realized the battery was depleted.

The third case involved a device that was not implanted when the physician realized the battery problem.

"Based on the low predicted rate of failure, we expect few, if any, additional events to occur," Medtronic's performance note says.