Many reported cases of sudden cardiac death not related to arrhythmias

NEW ORLEANS — Only about half of presumed cases of sudden cardiac death were proven by postmortem investigation to be cases of sudden arrhythmic death, according to the results of the POST SCD study, presented at the American Heart Association Scientific Sessions.

“Incidence estimates of SCD vary widely depending on data sources and definitions,” Zian H. Tseng, MD, MAS, associate professor in residence, cardiac electrophysiology section, University of California, San Francisco, said in a presentation.

The researchers reviewed all deaths reported to the San Francisco County, California, medical examiner between Feb. 1, 2011 and March 1, 2014 to identify incidents of SCD in patients aged 18 to 90 years. Detailed reports of out-of-hospital death autopsies, toxicology and histology reports were studied. The researchers also examined all county death certificates for possible instances of SCD not reported to the medical examiner.

The researchers found that 541 of 3,658 out-of-hospital deaths were attributed to SCDs over a period of 37 months (mean age, 63 years; 69% men), of which 525 (97%) were autopsied.

There were 89 additional SCDs within 3 weeks of immediate medical care with death certificate, making them ineligible for autopsy. These deaths, however, were included in citywide incidence of 28.9 per 100,000 person-years and showed differences by sex and race (P < .0005).

Sixty-five percent of patients (n = 342) had no cardiac history.

The leading cause of death was coronary disease (32%), followed by occult overdose (14%), cardiomyopathy (10%), hypertrophy (9%) and neurologic (5%).

Overall, 56% of the cases were due to sudden arrhythmic death, with 4% cardiac but not arrhythmic and 40% non-cardiac.

Among witnessed SCDs, ventricular tachycardia/ventricular fibrillation was present in 91% of those with an arrhythmic cause of death (P < .0001), while pulseless electrical activity rhythm was present in 87% of those with a non-arrhythmic cause of death (P < .0001), according to the researchers.

Incidence rates varied by race and sex, with men at more risk than women and black individuals at more risk than individuals from other races or ethnicities, the researchers found.

“Reliance on EMS records and/or death certificates is insufficient for accurate determination of SCD incidence,” Tseng said. “To reduce overall public health burden of SCD, in addition to CAD, efforts also should be directed toward screening, treating and preventing [overdose], neurologic diseases, hypertrophy and cardiomyopathy.” – by Dave Quaile

Reference:

Tseng, ZH, et al. CSSR.04: Hi Impact EP Registries and Clinical Trials. Presented at: American Heart Association Scientific Sessions; Nov. 12-16, 2016; New Orleans.

Disclosure : Tseng reports receiving an NIH research grant.