Danish researchers explains Sudden Cardiac Death in the young

Introduction
Most studies on Sudden Cardiac Death (SCD) in the young are based on samples in selected groups.

This is the first nationwide study (population 5.4 million) to describe incidences of SCD in the 1-35 years old and to report autopsy frequencies in presumed SCD by systematic evaluation of all deaths.

Objectives
The purpose of this study was to establish the precise incidence rate of SCD and to report autopsy ratios in presumed SCD cases in the Danish population aged between 1-35 years (2.4 million inhabitants in the age group).

Methods
All deaths in Denmark from 2000-2006 in the 1-35 years old were included. The death certificates were reviewed independently by two physicians. Information on previously known disease was retrieved from The National Patient Registry. The number of persons autopsied was ascertained and autopsy reports were read. Cause of death was revised based on autopsy findings. We defined SCD as a natural non-traumatic sudden death of cardiac cause occurring in a person last seen alive and well 24 hours prior to death.

Results
In the 7-year study period there were a total of 6,629 deaths in the 1-35 years old in Denmark. From death certificates we identified 619 presumed SCD cases. Of these, 165 (27% of presumed SCD) were not autopsied. When autopsied (n=454), cardiac cause of death was established in 224 cases (49%), with the most common autopsy findings being pulmonary embolism (n=49), ischemic heart disease (n=39), aorta dissection (n=23), and myocarditis (n=23). In 94 (21%) cases death was of non-cardiac cause. In 136 (30%) cases no cause of death was established during autopsy and they were subsequently denoted sudden arrhythmic death syndrome, SADS. In 103 (62%) of the non-autopsied cases cause of death was denoted unknown/arrhythmic. The majority of SCD were out-of-hospital (86%). 54% were awake at time of death and 31% died during sleep. Annual incidence rate of definite SCD (autopsied cases) is 2.1/100,000, and for SADS 0.8/100,000.

Conclusions
This is, to our knowledge, the largest and most thorough study on SCD in the young, and the first to report precise incidence rates on presumed and definite SCD in the young. Of the presumed SCD victims 73% were autopsied. Autopsy-negative cases (SADS) were common.