Prospective Countywide Surveillance and Autopsy Characterization of Sudden Cardiac Death: POST SCD Study

Area of Science:

• Cardiology
• Forensic Pathology
• Public Health

Background:

• Sudden cardiac death (SCD) incidence is underestimated due to reliance on emergency medical services records and death certificates.
• Over 90% of SCDs occur out-of-hospital, with causes often presumed due to infrequent autopsies.

Purpose of the Study:

• To determine the precise incidence and autopsy-defined causes of all sudden cardiac deaths (SCDs) in a metropolitan area.
• To investigate if postmortem examinations identify actual sudden arrhythmic deaths among presumed SCDs.

Main Methods:

• Prospective identification of out-of-hospital cardiac arrest deaths (18-90 years) in San Francisco County over three years.
• Autopsy, toxicology, and histology performed via medical examiner surveillance; World Health Organization (WHO) SCD criteria applied.
• Review of death certificates for missed SCDs and adjudication by a multidisciplinary committee.

Main Results:

• 541 (59%) of 912 out-of-hospital cardiac arrests met WHO SCD criteria; 525 underwent autopsy.
• Leading causes included coronary disease (32%), occult overdose (13.5%), and cardiomyopathy (10%).
• Autopsy-defined sudden arrhythmic deaths constituted 55.8% of WHO-defined SCDs, with 98% showing structural cardiac disease.

Conclusions:

• Forty percent of cardiac arrest deaths were not sudden or unexpected; nearly half of presumed SCDs were not arrhythmic.
• Findings challenge the accuracy of WHO criteria and emergency medical services records for SCD in mortality data, clinical trials, and cohort studies.