How pacemakers can help solve forensic cases and reveal true cause of death

Pacemakers and other cardiac devices can help solve forensic cases, according to a study presented at EHRA EUROPACE – CARDIOSTIM 2017.

Some 30% of cases remain unsolved because either the cause or the time of death remains uncertain even after autopsies, specialists say but the new and sophisticated devices could reveal important clues regarding these uncertainties and help solve the cases. The only issue is, cardiologists say, that current investigation procedures do not routinely involve the interrogation of these devices.

“In forensic medicine around 30% of cases remain unsolved because the cause or time of death after autopsy remains unclear,” said lead author Dr Philipp Lacour, a cardiologist at Charité – Medical University of Berlin, Germany. “The number of implanted cardiac devices with sophisticated diagnostic functions is increasing and we thought interrogating them might help to shed light on these unclear deaths,” he added. “Currently, device interrogation is not routinely performed after autopsy.”

To prove their claims, researchers conducted, in cooperation with the Department of Forensic Medicine at Charité – the Medical University of Berlin, an investigation analysing more than 5 000 autopsies from a five-year period. Of these, 150 cases had an implantable cardiac device which was removed from the body during the autopsy.

The explanted devices included 107 pacemakers, 22 implantable cardioverter defibrillators (ICDs), 14 cardiac resynchronization therapy (CRT) systems, and six implantable loop recorders. The devices were interrogated by two electrophysiologists to determine time and cause of death, and device failure.

According to the findings, in 76% of cases, time of death was established using data coming from the device. And the time of death was accurate down to the last minute, when the patient had fast heart rates, at the end of life.

In other cases, scientists used changes in seven parameters to assign the time of death. These included lead impedance and pacing threshold.

“At the end of life, lead impedance rises because of changes in the heart muscle and pacing climbs to 100% because the device doesn’t detect any heart rhythm.,” Lacour said in a press statement.

When it comes to causes of death, the interrogation of devices was able to provide answers for 24% of the cases, including in instances that involved bradycardia, tachycardia, ventricular fibrillation, and device malfunctions.

“The cause of death was most easily determined when the patient had a lethal arrhythmia such as tachycardia which was documented by the device,” said Dr Lacour. “For example, a ventricular fibrillation was recorded by a pacemaker, which did not intervene because it was not a defibrillator, and showed us that this arrhythmia caused the death.”

Device malfunction occurred in 7% of cases. This included hardware failures such as a broken lead, algorithm issues meaning the device did not recognise an arrhythmia or deliver a shock when it occurred, or a programming issue where the shock setting was insufficient to terminate an arrhythmia.

According to their calculations, the interrogation of cardiac devices was able to bring down the percentage of unknown causes of death from 30%, recorded with autopsy alone, to around 10–20%. It proved that by using this complementary method,  85% of all unclear deaths can be solved.

“We think device interrogation should be routinely performed after autopsy in all forensic cases,” continued Dr Lacour. “It helps determine the time and cause of death and identifies device malfunctions that might otherwise have gone unnoticed and should be highlighted to manufacturers and health departments.”

The doctors also say that in order to receive accurate information, the interrogation of cardiac devices such as pacemakers should be made as soon as possible after death, ideally within two weeks after the patient has died.