Most patients given an implantable cardioverter defibrillator do not know what should happen to it during their final weeks of life, a study shows.

American College of Cardiology guidance from 2010 recommends turning off defibrillators in the final weeks of a terminal illness to prevent shocks being delivered during the dying process, which can be painful and prolong the process.

However, if the device includes a pacemaker function, this can remain operational.

The guidelines also recommend these end-of-life issues are discussed with patients when they first receive the device.