Sudden cardiac death (SCD) is defined as the natural sudden unexpected death due to a cardiac cause (cessation of cardiac activity)
In witnessed cases, as an acute change in cardiovascular status with time to death being <1 hour
In unwitnessed cases, as a person last seen alive and functioning normally <24 hours before being found undead
Sudden cardiac arrest - there are witnesses around that can intervene
Unexpected collapse due to cardiac cause (sudden cessation of cardiac activity resulting in individual becoming unresponsive with no normal breathing and no signs of circulation) in which CPR and/or defibrillation is successfully provided
Sport-related SCD is defined as a SCD occurring during or within one hour after exercise