Sudden cardiac deaths are rare with pacemakers or ICDs

A prospective analysis found 4.3 percent of sudden cardiac deaths in San Francisco were in patients with pacemakers or implantable cardioverter-defibrillators (ICDs). Half of the deaths were related to the devices, and the most common cause of death was ventricular tachycardia (VT) or ventricular fibrillation (VF).

Zian H. Tseng, MD, MAS, of the University of California, San Francisco, and colleagues published their findings online in JAMA Internal Medicine on June 22. They mentioned more than 3 million people in the U.S. have a pacemaker or ICD.

In this analysis, the researchers performed autopsies on 499 of 517 sudden cardiac deaths in San Francisco from Jan. 1, 2011 to Nov. 30, 2013. They defined sudden cardiac deaths as unexpected death within an hour of acute symptom onset if witnessed or within 24 hours of the last observation at baseline if the death was not witnessed.

During the 35-month period, there were 22 sudden cardiac deaths in patients with pacemakers or ICDs. Fourteen patients had pacemakers and eight had ICDs. Of the eight patients with ICDs, six had ischemic cardiomyopathy and two had dilated cardiomyopathy.

Tseng et al wrote that none of the patients had lethal levels of drugs in their systems when they died. They added that six patients had a noncardiac cause of sudden death, including two cases of intracranial hemorrhage, two cases of pneumonia, one case of massive pulmonary hemorrhage and one case of blunt force trauma to the head and neck.

Eight of the 14 patients who had sudden cardiac deaths with pacemakers died of arrhythmic causes, including six cases of VF, one case of presumed profound bradyarrythmia or asystole and one case of unknown rhythm. Four of the deaths were attributed to device concerns.

Of the eight patients with ICDs, seven died of arrhythmic causes (six VF cases and one VT case). The other patient died of massive subarachnoid hemorrhage.

The researchers said that 712 San Francisco residents had an ICD during the study period. Of these patients, 15.3 percent died, and 6.4 percent of the deaths were sudden cardiac deaths with a device concern.

“Current passive surveillance efforts may underestimate device malfunction,” they wrote. “A prospective, systematic approach incorporating these methods 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.”