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Misclassification, overestimation common in cardiac arrest deaths
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Approximately 40% of deaths caused by cardiac arrest were neither sudden nor unexpected, and nearly half of cases of sudden cardiac death were not arrhythmic, according to a study published in Circulation.
“Our methods may provide an outline for medical examiner or coroner protocols for the systematic examination of these out-of-hospital natural deaths, which are rarely investigated in the community,” Ellen G. Moffatt, MD, assistant clinical professor of pathology at University of California, San Francisco, said in a press release.
Deaths in California
Zian H. Tseng, MD, MAS, professor of medicine at University of California, San Francisco, and colleagues analyzed data from 20,440 patients who died from Feb. 1, 2011, to March 1, 2014, in San Francisco.
Information on these patients was reviewed by an assistant medical examiner and a cardiac electrophysiologist to identify those with out-of-hospital cardiac arrest for a detailed autopsy with histology and toxicology. Sudden cardiac death was defined according to WHO criteria.
Of the deaths that occurred during the 37-month period, 12,671 were reported to the medical examiner and 912 were identified as out-of-hospital cardiac arrest deaths. More than half of these deaths met WHO sudden cardiac death criteria (59%; mean age, 63 years; 69% men), and 97% of the patients who died from sudden cardiac death were autopsied.
With 3 weeks of active medical care, an additional 89 patients who died from WHO-defined sudden cardiac death were identified with a death certificate signed by the attending physician. These patients were ineligible for autopsy but were included in the incidence rate of 29.6 per 100,000 person-years. The highest rates were seen in black men (P < .0001).
Major causes of death
Of the 525 patients who had sudden cardiac death, 57% did not have a cardiac history. The major causes of death in these patients were occult overdose (13.5%), CAD (32%), cardiac hypertrophy (8%), cardiomyopathy (10%) and neurological (5.5%). Sudden arrhythmic death occurred in 55.8% of patients who were autopsied, 53% of unwitnessed sudden cardiac deaths and 65% of witnessed sudden cardiac deaths. Nearly all the sudden arrhythmic death cohort (98%) had structural cardiac disease.
“These data provide an unbiased, real-world picture of the contemporary epidemiology, burden and underlying causes of sudden death in the community, and have implications for the accuracy of [sudden cardiac deaths] and aggregate mortality data as defined by death certificates or conventional criteria in clinical trials and cohort studies,” Tseng and colleagues wrote. “Our methods may also provide an outline for medical examiner or coroner protocols for the systematic examination of these out-of-hospital natural deaths, which are rarely investigated in the community.”
In a related editorial, Robert J. Myerburg, MD, professor of medicine at University of Miami, wrote: “The conclusion that 40% of events appearing to be [sudden cardiac deaths] were not sudden or unexpected is sobering and requires our attention as we classify [sudden arrhythmic deaths] in the design and execution of future studies on this important topic. The converse perception, that the cumulative numbers still contain a large representation of events that are indeed cardiac-based [sudden cardiac deaths], and that there may be some undercounting, should not be lost as a result of the principles elucidated in this study.” – by Darlene Dobkowski
Disclosures: Tseng reports he received personal fees from Biotronik. Moffatt and Myerburg report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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