Customer Communications
Potential High Battery Impedance

Potential High Battery Impedance

InSyncŪ III Model 8042
Original Date of Communication: November 2015

View specific models that this applies to


As of May 10, 2021, approximately 500 devices remain active worldwide, from an original implant population of 96,800. In the United States, 200 active devices remain. Our modeling predicts an estimated failure rate between 0.16% and 0.6% for the remaining active devices. Due to the unpredictable nature of this issue, it is not possible to identify which devices might fail or when they might fail. The issue cannot be mitigated by programming changes or increasing patient follow-up frequency. InSync III CRT-pacemakers are no longer distributed.

Due to low estimated remaining active population, this advisory will be removed at our next semi-annual publish of this product performance website.

Initial Affected Population Number of Confirmed Advisory Related Events Estimated Remaining Active Population Current Malfunction Rate (confirmed malfunctions over total population)
96,800 Worldwide (39,900 United States) 171 Worldwide (95 United States) 500 Worldwide (200 United States)

0.18% Worldwide (0.24% United States)



All InSync® III Model 8042 Pacemakers


Medtronic has identified an issue related to long-term battery performance. Through 27 October 2015, Medtronic has confirmed 30 devices (0.03%) worldwide have been impacted by this issue, for which the root cause is unexpected high battery impedance.

Unexpected high battery impedance can result in the battery’s inability to supply sufficient electrical current, impacting device function. Twelve (12) of the 30 devices had reports of unexpected loss of pacing capture. The other 18 devices experienced some form of erratic behavior, including early elective replacement indication (ERI), significant fluctuations in remaining longevity estimates, and inaccurate lead impedances. Through 27 October 2015, events associated with this issue have occurred in devices with implant durations of 53 months or more. Medtronic has received one report of a patient death, where it is possible, but unconfirmed, that this issue was a contributing factor.

If pacing capture is compromised, some patients may experience a return of heart failure symptoms due to loss of biventricular pacing. In cases involving pacemaker-dependent patients, a loss of pacing capture could result in serious injury or death.

The Physician Letter for this issue is available at

Patient Management Recommendations (As of November 2015)

We realize that each patient requires unique clinical consideration. After consultation with Medtronic’s Independent Physician Quality Panel (IPQP), Medtronic offers the following recommendations for patients with an InSync III CRT-pacemaker:

  • Prophylactic device replacement in non-pacemaker-dependent patients is not recommended.
  • For pacemaker-dependent patients, physicians should carefully weigh the risks and benefits of device replacement to mitigate this issue on an individual patient basis
    • The estimated per patient mortality risk of this issue (0.007% to 0.02%) is comparable to the estimated per patient mortality risk of complications associated with an incremental, early device replacement (0.005%).
  • Continue routine patient follow up in accordance with standard practice, and advise patients to seek medical attention immediately if they experience new or unexpected symptoms.

Specific Models This Applies To 851050