Two-Fifths of 'SCD' Not Even Cardiac in Postmortem Study

Larry Hand

November 22, 2016

NEW ORLEANS, LA — In a study of officially classified out-of-hospital (OOH) sudden cardiac deaths (SCDs) in San Francisco, 40% turned out to be noncardiac in origin after further analysis postmortem, reported investigators here at the American Heart Association (AHA) 2016 Scientific Sessions[1].

Dr Zian H Tseng (University of California, San Francisco) and colleagues conducted a review of all deaths reported to the San Francisco medical examiner's (ME's) office between February 1, 2011 and March 1, 2014. Of the 20441 deaths reported, 525 were included through adjudication as SCDs.

San Francisco county has a single medical examiner office that serves area of 49 square miles and a population of 864,000. It is 33% Asian, 6.1% black, 15% Hispanic, and 48% white. Three ambulance companies for eight hospitals respond to about 85% of 911 calls.

"Investigation after such natural deaths is not routine ME practice. Autopsy seems to be a lost art," Tseng said during a presentation as background. Autopsy rates for OOH deaths are ranging from about 10% in the US to 23% in Finland, according to Tseng. "Somehow the Europeans always do a little better than us."

In addition to analyzing the deaths reported to the ME, they also analyzed all county death certificates retrieved quarterly from the Department of Public Health, as well as outside medical records obtainable through medicolegal authority.

They specifically reviewed data on past medical history, medications, paramedic run sheets and rhythms, witness/family investigations, and autopsy and toxicological findings. The overall autopsy rate was 83%.

They found that SCD incidence rates varied widely by sex and race, with black males at highest risk and Hispanic females at lowest risk. The most common non–sudden arrhythmia deaths were from occult overdose or neurological causes.

Coronary artery disease (CAD) was associated with about a third of the SCDs and 57% of the sudden arrhythmia deaths.

Of the 525 adjudicated SCDs, 293 (56%) were of cardiac arrhythmic origin, 22 (4%) were of nonarrhythmic cardiac origin, and 210 (40%) were of noncardiac origin.

Etiologies varied widely, from chronic CAD (117 deaths) to cardiomyopathy (53 deaths) to hypertrophy (44 deaths) to aspiration/asphyxia (five deaths).

In terms of premortem conditions, hypertension affected 55% of SCDs and 60% of sudden arrhythmia deaths, while tobacco use was present in 40% of SCD cases and 39% of sudden arrhythmia deaths.

Tseng said during the presentation that the results may not be generalizable to other cities, mostly due to the population diversity.

He later told heartwire from Medscape, "I think it's a peek at what we, as clinicians, never get to see, which is postmortem. Those are perhaps the most important lessons that we can learn as clinicians. Did we prevent the diseases that we were trying to prevent or the conditions we were trying to treat?

"Surprisingly, nearly half were not even cardiac. It's really reflective of ongoing epidemics of opiate-addiction trends, for example, and also neurologic causes. But importantly, with coronary disease less and less of the underlying causes, we have hypertrophy and other cardiomyopathies making up the rest of the pie," he said.

Dr Graham Nichol (University of Washington, Harborview Center for Prehospital Emergency Care and Clinical Trial Center, Seattle), discussant for the presentation, said, "This large study from San Francisco is very interesting, but it's a little unclear how it generalizes to other communities. The etiology of cardiac arrest varies from region to region.

"It is important to recognize that the proportion of arrests that are due to any particular etiology, whether arrhythmic or coronary artery disease, depends a lot on which population you look at and how you ascertain and how you define the incidence of significant coronary artery disease," he said.

Tseng reported receiving support from the National Institutes of Health.

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