BACKGROUND: Interrogations of cardiac implantable electronic devices (CIEDs: pacemaker, defibrillator, Cardiac Resynchronization Therapy Implantable Cardioverter Defibrillator/Pacemaker or loop recorder) are rarely performed at autopsies of sudden or unexplained death. Therefore, data on the role of nonselective post-mortem CIED analysis is lacking.

OBJECTIVE: To obtain post-mortem CIED data of patients undergoing autopsy and thereby reveal the cause of death or device malfunction in a prospective study.

METHODS: From April 18^th, 2016, to November, 11^th, 2021 full autopsy, device removal and interrogation were performed by the Institute of Legal Medicine and the Department of Electrophysiology of the University Hospital of Cologne in all patients undergoing autopsy and having a CIED as part of the clinical routine.

RESULTS: 149 patients undergoing autopsy had CIEDs removed and analyzed. 24 were defibrillators, 102 were pacemakers, 7 were loop recorders, one was a leadless pacer and 16 were Cardiac Resynchronization Therapy Implantable Cardioverter Defibrillators (CRT-D). 84 (56 %) patients died of a natural cause, 37 (25 %) of an unnatural cause. 28 (19 %) patients’ cause of death could not be determined. Overall, 61 (41 %) patients had documented arrhythmia in their Holter prior to their death.

Arrhythmias: At the time of death, 29 (19 %) patients had sustained tachyarrhythmia. 7 heart failure patients had atrial fibrillation, two of them with a heart rate exceeding 200 bpm. 16 patients suffered from ventricular fibrillation (VF) at their time of death. 10 of the patients with VF had a pacemaker, 4 had defibrillators, one of which had therapy turned off and the other three failed to terminate VF with ATP and shocks. Two had a CRT-D. 6 patients suffered from ventricular tachycardia (VT) at their time of death. One patient had a loop recorder which showed ventricular tachycardia not responding to external defibrillation at the time of death, 4 had a pacemaker, one had an ICD which failed to terminate VT. Two patients suffered from multiple episodes of asystole, recorded in their loop recorders, resulting in cardiac arrest at the time of death. One patient had a CRT-D and one patient a single-chamber-ICD with tachyarrhythmia detection turned off.

Complications: Device complications only occurred in 4 patients. Two of them had a ventricular lead warning, one with a decrease in the impedance two weeks before his death. One patient had an ICD showing artefacts sensed as VF days before his death causing two inappropriate shocks. The other patient suffered from indistinguishable low voltage electrical signal non-compatible to VT or VF criteria of his ICD at the time of death. No malfunctions could be found. Two patients with an ICD showed ventricular undersensing prior to death.

Two patients’ antitachycardia programming did not comply with current recommendations.

Four patients’ date of death could not be determined because of the device interrogation as the body was very decomposed when found (decrease in patient activity, sudden rise of ventricular stimulation, rise of impedance).

CONCLUSION: Systematic post-mortem interrogation in CIED patients undergoing autopsy was useful in assisting with determination of the mechanism, the time and cause of death in 149 patients. Current surveillance standards may underestimate device malfunction, programming mistakes or cardiac arrhythmia at the time of death.