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Current monitoring of ICDs, pacemakers may underestimate device malfunction
The current monitoring of patients with cardiac implantable electronic devices may underestimate device malfunctions, leading researchers to propose new systematic methods to determine accurate causes of sudden death in patients with cardiac devices.
“With the vast majority of out-of-hospital sudden deaths evaluated by medical examiners or coroners, [cardiac implantable electronic device] problems are often missed in the postmortem investigation, as they are not part of the routine evaluation,” Zian H. Tseng, MD, MAS, from the section of cardiac electrophysiology in the division of cardiology at University of California, San Francisco, said in a press release.
The researchers conducted an autopsy study of 517 sudden deaths that occurred from 2011 to Nov. 30, 2013, in San Francisco. Patients with pacemakers or implantable cardioverter defibrillators within this cohort were identified. The researchers performed full autopsy, toxicology, histology and device interrogation among these patients with cardiac implantable electronic devices to determine the incidence of device problems, including hardware failures, issues with device algorithms or programming and improper device selection.
Among the deaths observed, 22 patients had cardiac implantable electronic devices, including 14 with pacemakers and eight with ICDs. Six patients with implantable devices died due to noncardiac causes. Ventricular tachycardia or fibrillation was the cause of death in six patients with pacemakers and seven patients with ICDs.
The researchers identified device issues in 11 cases, including four patients with pacemakers and seven patients with ICDs. Hardware failure contributed directly to patient death in three cases: two patients who experienced lead fractures and one with a rapid depletion of battery resulting in a sudden drop in pacing output. Other observed device problems included five incidences of ventricular fibrillation undersensing among patients with ICDs; one case of missed ventricular tachycardia due to a programming issue; one case of improper device selection; and one patient with pneumonia and a pacemaker with concerns about lead fracture.
In a separate study, the researchers also evaluated cases of sudden cardiac death among adult San Francisco residents with ICDs. Among 712 San Francisco residents identified with ICDs during the study period, 109 deaths occurred (cumulative incidence rate, 15.3%). The researchers noted that issues with ICDs represented 6.4% of these deaths.
“Current passive surveillance efforts may underestimate device malfunction,” the researchers concluded. “A prospective, systematic approach incorporating [systematic interrogation and autopsy] can provide unbiased data regarding what may lead to sudden death in individuals with cardiac implantable electronic devices and improve surveillance for cardiac implantable electronic device problems.” – by Adam Taliercio
Disclosure: Tseng reports receiving honoraria from Biotronik. One researcher reports receiving educational travel grants from Boston Scientific and Medtronik, and another researcher reports receiving grant funding from Zoll.