Objectives: To determine the causes of sudden cardiac death in people aged 35 years or younger.
Design and setting: A review of all autopsies performed between 1 January 1994 and 31 December 2002 at a major Sydney forensic medicine department serving an area with over 2 million people.
Main outcome measures: Incidence of various types of cardiac disease causing sudden death in those aged <or= 35 years; proportion of deaths in which no cause was found at autopsy.
Results: There were 10 199 autopsies performed during the study period. Of these, 2986 (29.2%) deaths occurred in people aged <or= 35 years; 193 were classified as sudden cardiac deaths. The cause of sudden death in this group was not established in 60 (31%), and was presumed to be due to primary arrhythmogenic disorders. Coronary artery disease occurred in 46 (24%), hypertrophic cardiomyopathy/unexplained left ventricular hypertrophy in 29 (15%), and myocarditis in 23 (12%).
Conclusions: Unexplained deaths, presumed to result from sudden primary arrhythmogenic causes, occur in young Australians with structurally normal hearts. That underlying disease-causing genetic defects may be involved has clinical implications for family members.