A worldwide experience of the management of battery failures and chronic device retrieval of the Nanostim leadless pacemaker.

Background: The Nanostim leadless pacemaker (LP) met the primary endpoints in an investigational device exemption trial, and was shown to be fully retrievable percutaneously. In October 2016, St Jude Medical issued a worldwide alert of a battery malfunction that caused lost pacing output and LP communication.

Objective: To report the battery failure mechanism and incidence and the worldwide patient management, including device retrieval experiences.

Methods: The affected LP battery is a custom lithium-carbon monofluoride cell. These were returned after failure and underwent analysis assessing electronics and battery performance. Data were collected in ongoing clinical studies when LPs were abandoned or retrieved.

Results: Of 1423 LPs implanted worldwide, there were 34 battery failures, occurring at 2.9 ± 0.4 years with no instances of associated patient injury. Analysis of returned batteries revealed an increase in battery resistance caused by insufficient electrolyte availability at the cathode/anode interface. A total of 66 of 73 retrieval attempts were successful (90.4%; implant duration range: 0.2-4.0 years). The LP docking button was inaccessible in 6 patients, and the docking button detached from the LP during retrieval in 1 patient. There was 1 case of arteriovenous fistula and another case of the LP docking button migrating into the pulmonary artery. There were also 115 non-LP retrieval patients after the advisory who received an additional pacemaker, with no adverse device-to-device interactions reported.

Conclusion: As with standard pacers, LPs can have critical battery failures. Chronic retrieval of LPs is safe and efficacious.