**2.1 Definition of sudden cardiac death**

Sudden cardiac death (SCD) is defined as the sudden and unexpected death of a person who was otherwise stable prior to the event [8]. If the death is witnessed and occurs within 1 hour of onset of symptoms, it is classified as SCD. If the sudden and unexpected death is not witnessed, then SCD is declared if it occurs within 24 hours of the person last being seen alive and well.
