Postmortem Examination of Pacemakers and Defibrillators Provides Useful Clinical Clues

The removal and examination of implanted cardiovascular devices at the time of autopsy can improve accuracy when establishing timing and cause of death, a small study shows. 

In an interview with TCTMD, Sunil K. Sinha, MD (Johns Hopkins University School of Medicine, Baltimore, MD), said little attention has been given historically to pacemakers or cardioverter-defibrillators (ICDs) after death, but now his team and others are starting to see their potential to provide important and otherwise unseen clues.

In a paper published online today ahead of print in the Journal of the American College of Cardiology, Sinha and colleagues advocate for the routine examination of these devices regardless of the suspected cause of death.

Guidelines from the Heart Rhythm Society and the Association for European Cardiovascular Pathology encourage postmortem interrogation of implantable cardiac devices in cases of sudden cardiac death. Sinha said the results of his study support those recommendations but take them a step further by suggesting that the devices be removed and undergo examination even when the cause of death is not sudden.

“Very often when someone dies, especially if it’s an unwitnessed death, we can hypothesize what the probable cause of death is, but unless we do an autopsy and look at all the possible clues available we really ‘don’t know what we don’t know,’ as the old saying goes,” Sinha noted.

For the study, autopsies were performed on 84 individuals with either a pacemaker (n = 37) or defibrillator (n = 47). The devices were removed and examined by an electrophysiologist for clinically significant alerts—classified as sustained atrial or ventricular tachyarrhythmias within 24 hours of death, or elevated fluid values suggestive of intrathoracic impedance—and then sent to the manufacturer for technical analysis. Of these, 43 involved cases of sudden death, with the primary cause in most of those being cardiac.

The researchers uncovered clinically significant alerts in 63% of the sudden deaths. But more surprisingly, the alerts also were found in approximately 20% of those with nonsudden cardiac death. Most of the alerts in the nonsudden cardiac death group were due to elevated intrathoracic impedance.

As a group, defibrillators were more likely than pacemakers to trigger alerts.

A Silver Lining

The study, taken together with another similar investigation published last year in JAMA Internal Medicine, represents “compelling collective evidence” for more widespread use of postmortem examination of pacemakers and defibrillators in cases of sudden cardiac death, say Michael J. Ackerman, MD, PhD and John R. Giudicessi, MD, PhD (both Mayo Clinic, Rochester, MN), in an accompanying editorial.

They add that increased emphasis on examination of the devices also “has the potential to add a silver lining to otherwise tragic deaths” by providing a mechanism to identify hardware failures or performance issues more quickly.

Sinha agreed, noting that current postmarketing surveillance by manufacturers is primarily based on examining devices that are returned to them at the time of replacement in patients who are still alive.