Drug Overdoses Masquerading as Sudden Cardiac Death Common

Megan Brooks

August 14, 2020

A comprehensive postmortem toxicology study of out-of-hospital cardiac arrest (OHCA) deaths in San Francisco, California, has shown that more than 1 in 6 were actually occult drug overdose deaths, which means that national overdose fatality rates may be substantially underestimated.

"Drug overdose deaths are hiding in plain sight as sudden cardiac deaths," Zian H. Tseng, MD, cardiologist and electrophysiologist at the University of California, San Francisco, told Medscape Medical News.

"This is happening in every community throughout the country and in every country in the world, because unless you do toxicology in every cardiac arrest, you won't recognize it," said Tseng.

Of course, that's not feasible, Tseng admitted.

"Medical examiners and coroners have limited resources. They don't have the bandwidth or the funding or the manpower to investigate all these natural deaths, so they are presumed cardiac on death certificates 90% of the time," Tseng said.

The study was published online August 11 in Annals of Internal Medicine.

Tseng and colleagues reviewed autopsy and toxicology data on an initial cohort of 525 individuals whose deaths were initially ruled as OHCA in San Francisco.

Seventy-nine (15%) of these "cardiac" deaths were subsequently determined to be occult overdose deaths after review by an expert panel consisting of the medical examiner, a cardiac pathologist, a neurologist, and two cardiologists/cardiac electrophysiologists.

In an extended cohort of an additional 242 OHCA deaths, 54 (22%) were adjudicated as occult drug overdose deaths.

On the basis of their findings, Tseng offered this "back of the envelope" calculation.

"In 2016, I believe, there were around 60,000 recognized overdose deaths nationally. That same year, there were about 380,000 cardiac arrests. So if you take 1 in 6 of that, that's another 60,000 cases that were missed as overdoses. So we think it's potentially an undercount by a factor of two the scale of the overdose epidemic," he told Medscape Medical News.

Toxicology showed that the most common drug classes in occult overdose OHCA deaths were opioids, sedative-hypnotics, and stimulants. Most occult overdose OHCA deaths involved multiple drugs; approximately half of intoxicants were prescription medications.

From this study, the burden of drug overdose deaths is far greater than national estimates now suggest, Tseng said.

He and his colleagues also think naloxone should be considered in selected OHCA resuscitations.

"We think this study might provide evidence that we should incorporate Narcan in resuscitation efforts. It's a cheap and very effective reversal agent," Tseng said. "There is very little risk to give it to someone in cardiac arrest and see if it might revive them. It very well may save their life."

Funding for the study was provided by the National Heart, Lung, and Blood Institute. The authors have disclosed no relevant financial relationships.

Ann Intern Med. Published online August 11, 2020. Abstract

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