Implantable cardioverter defibrillators (ICD) - risk of loss/ pacing therapy

(Medtronic) once elective replacement indicator (ERI) is reached there is a risk of loss of ICD/pacing therapy from rapid battery depletion that occurs around 2.5 years after implantation. (MDA/2012/014)

CAS deadlines

Action underway: 22 March 2012, action complete: 22 June 2012


Implantable cardioverter defibrillators (ICD)

Implantable cardioverter defibrillators (ICD).

EnTrust VR/DR/AT

Models: D153ATG, D153DRG, D153VRC, D154ATG, D154DRG, and D154VRC.

Manufactured by Medtronic.


Risk of loss of ICD/pacing therapy after elective replacement indicator (ERI) is reached, due to rapid battery depletion occurring approximately two and an half years after implantation.

Approximately 69,000 EnTrust devices have been sold worldwide since 2005, with just over 1,000 sold in the UK. To date only 0.15% of single chamber EnTrust ICDs and 0.04% of dual chamber EnTrust ICDs worldwide are reported to have experienced rapid voltage decline. Although the issue does not appear to affect devices implanted for less than 30 months, the failure rate as implant duration increases is as yet unknown.

Medtronic issued a Field Safety Notice (38Kb) addressing this issue on 6 March 2012.

Fig 1: Medtronic’s analysis of ICD failures
The graph shows examples of a number of ICDs which have experienced rapid voltage drop from 3.0V to 2.61V over a time period ranging from approximately one week to six months.  
Note:  This graph may not be characteristic of every possible voltage curve drop due to this issue.  The sole purpose of this graph is to illustrate rapid voltage decline to 2.61V (ERI), not the duration of time between ERI and EOL.

EnTrust Rapid Voltage Decline

End of life (EOL) is triggered 90 days after ERI or after two excessive charge time events (>16 seconds) or if the battery voltage is 2.55V.

In EnTrust devices that experienced rapid voltage decline, time between measurements of approximately 3.0V and 2.61V (ERI) ranged from four to 198 days (mean 71, median 56).  

In EnTrust devices that experienced rapid voltage decline, time between ERI and EOL ranged from six to 96 days (mean 41, median 26), based upon data available from the 9 ICDs that experienced charge circuit timeout events during automatic capacitor formation prior to device explant.

In the event of a battery short circuit the ICD may not be able to provide the required therapy for the three month period generally expected post ERI. Although incidents of charge circuit timeout have occurred, there have been no reports to date of death or serious injury associated with this failure.

The rapid voltage drop has been linked to an internal short circuit within the ICD battery.  Although the exact root cause is still being investigated by the manufacturer, the issue appears to be specific to EnTrust devices.  Failure rate data for other Medtronic ICD models incorporating the same battery model currently indicate that they are not affected.  Furthermore, these batteries are not used by other manufacturers.


  • Follow-up all patients with EnTrust ICDs urgently:

    • within one month if the device has been implanted for more than 28 months
    • within three months in other cases; in order to:
      • ensure audible alerts for ‘Low Battery Voltage ERI’ and ‘Excessive Charge Time EOL’ are programmed ON (status can be viewed over CareLink)
      • advise patients to contact centres immediately if the alert sounds
      • compare battery voltage with values from previous follow ups for evidence of rapid battery voltage drop (see Fig 1).
  • Replace ICDs where ERI has been reached in the presence of rapid battery voltage drop, within two weeks.
  • Continue to review all patients every three months.
  • Ensure all patients are enrolled on CareLink, in discussion with the manufacturer.
  • Prophylactic replacement of these devices is not recommended except in exceptional circumstances.

Action by

All cardiologists and cardiac physiologists who manage patients implanted with ICDs


This MDA has been sent to:  

  • NHS trusts in England (chief executives)
  • Care Quality Commission (CQC) (Headquarters) for information
  • HSC trusts in Northern Ireland (chief executives)
  • NHS boards in Scotland (equipment coordinators)
  • NHS boards and trusts in Wales (chief executives)

Onward distribution

Please bring this notice to the attention of relevant employees in your establishment. Below is a suggested list of recipients.

CAS and SABS (NI) liaison officers for onward distribution to all relevant staff including:

  • Cardiac laboratory technicians
  • Cardiac pacing technicians
  • Cardiac physiologists
  • Cardiologists
  • Cardiothoracic surgeons
  • Clinical governance leads
  • Medical directors
  • Nursing executive directors

Independent distribution

Establishments registered with the Care Quality Commission (CQC) (England only) 
This alert should be read by:

  • Hospitals in the independent sector
  • Private medical practitioners

Please note: CQC and OFSTED do not distribute these alerts. Independent healthcare providers and social care providers can sign up to receive MDAs directly from the Department of Health’s Central Alerting System (CAS) by sending an email to: and requesting this facility.

Manufacturer contact


Mrs Lezlie Bridge
Medtronic Limited
Building 9
Croxley Green Business Centre
Hatters Lane
Watford WD18 8WW

Tel: 01923 212 213 / 07740 899 216
Fax: 01923 225 273



If you have any comments or feedback on this Medical Device Alert please email us at:


If you are in England, please send enquiries about this notice to the MHRA, quoting reference number MDA/2012/014 or 2012/002/029/291/009

Technical aspects

Simon Holmes or Hazel Randall
Medicines & Healthcare products Regulatory Agency
Floor 4
151 Buckingham Palace Road
London SW1W 9SZ

Tel: 020 3080 7240 / 7287
Fax: 020 8754 3965

Email: or

Clinical aspects

Dr Nicola Lennard
Medicines & Healthcare products Regulatory Agency
Floor 4
151 Buckingham Palace Road
London SW1W 9SZ

Tel: 020 3080 7126
Fax: 020 8754 3965


How to report adverse incidents

Please report via our website: Reporting adverse incidents involving medical devices
Further information about CAS can be found on the CAS website

Northern Ireland

Alerts in Northern Ireland will continue to be distributed via the NI SABS system.

Enquiries and adverse incident reports in Northern Ireland should be addressed to:

Northern Ireland Adverse Incident Centre
Health Estates Investment Group
Room 17
Annex 6
Castle Buildings
Stormont Estate
Dundonald BT4 3SQ

Tel:    02890 523 704
Fax:   02890 523 900


How to report adverse incidents in Northern Ireland

Please report directly to NIAIC, further information can be found on the NIAIC website

Further information about SABS can be found on the SABS website


Enquiries and adverse incident reports in Scotland should be addressed to:

Incident Reporting and Investigation Centre
Health Facilities Scotland
NHS National Services Scotland
Gyle Square
1 South Gyle Crescent
Edinburgh EH12 9EB

Tel: 0131 275 7575
Fax: 0131 314 0722


Health Facilities Scotland Incident Reporting and Investigation Centre (IRIC)Health Facilities Scotland Incident Reporting and Investigation Centre (IRIC)


Enquiries in Wales should be addressed to:

Dr Chris Jones
Medical Director
Medical Device Alerts
Welsh Assembly Government
Cathays Park
Cardiff CF10 3NQ

Tel: 029 2082 3922


Download documents

Medical Device Alert: Implantable cardioverter defibrillators (ICD) manufactured by Medtronic (MDA/2012/014) (699Kb)

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