Fatal Overdoses Often Mistaken for Cardiac Arrest


By Nicole Lou

Deaths from drug overdose often gave the impression of being sudden cardiac death until an autopsy determined otherwise, according to a study.

Autopsy adjudication determined occult overdose actually caused death for 15% of 525 cases initially ruled as out-of-hospital cardiac arrest (OHCA), reported Zian Tseng, MD, MAS, of the University of California San Francisco, and colleagues.

With an additional 242 OHCA deaths after extending the study period, 22.3% were determined to be occult overdoses upon adjudication by an expert panel consisting of the medical examiner, a cardiac pathologist, a neurologist, and two cardiologists (or cardiac electrophysiologists), Tseng's group reported.

"Published national mortality estimates based on recognized overdoses may be a substantial underestimate of the true burden, because occult overdose deaths masquerading as sudden cardiac deaths are missed without postmortem toxicologic analysis," the investigators said, noting that some overdose cases may be missed if there is no history of ingestion or evidence of drug use at the scene.

The most common drug classes were opioids (68.4% and 48.1% for the initial and extended periods, respectively), sedative-hypnotics (49.4% and 51.9%), and stimulants (48.1% and 51.9%).

"Most occult overdose OHCA deaths involved multiple drugs, including opioids, and approximately one half of intoxicants were prescribed. Our findings affirm the need for continued efforts to combat the opioid epidemic and consideration of naloxone in selected OHCA resuscitations," study authors said.

Tseng's team previously reported that 40% of so-called "sudden cardiac deaths" in San Francisco County in 2011-2014 were not unforeseen and were noncardiac.

Their present case-series analysis of deaths attended by San Francisco EMS included adults who died at up to 90 years of age. The initial cohort included OHCA deaths from Feb. 1, 2011 to March 1, 2014, which all received full autopsies. The extended cohort counted mortalities from March 1, 2014 to Dec. 31, 2017, when not all received autopsies.

"Although we used convenience sampling in the extended cohort, we maintained the same inclusion and exclusion criteria; thus, any resultant bias is likely to be balanced and limited," Tseng and colleagues wrote.

People who died from overdose in the study were younger and more commonly White or Black than Asian or Latino.

San Francisco has an age-adjusted overdose mortality rate of 21 per 100,000 persons, "nearly identical" to the median overdose mortality rate among all states (21.4 per 100,000 persons), they said.

Nevertheless, they cautioned that their findings may not be generalizable to other communities with different demographic characteristics and prevalence of substance use.


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