The survival statistics for out-of-hospital cardiac ar- rest remain disappointing, with an estimated 10% overall survival rate.S2.2.2-44 Among the subgroup of 70% of out-of-hospital cardiac arrests that occur in the home, survival is 6%. The best reported outcomes are from locations with highly developed and publicly vis- ible emergency rescue response, along with the com- bination of public location of cardiac arrest, bystander witnesses willing to provide CPR, first responders arriv- ing quickly, shockable rhythm at initial contact, avail- ability of automated external defibrillators (AEDs), and possibly a benefit from telecommunication-directed Survival to hospital discharge after in- hospital cardiac arrests is estimated to be 24%.S2.2.2-48 In all settings, survival statistics appear to be better when rhythms recorded by responders are shockable (VF, pulseless VT), compared with pulseless electrical activ- ity or asystole.S2.2.2-49 Although the apparent increase in the incidence of pulseless electrical activity or asystole could be due to the later arrival of medical care, the decrease in the incidence of shockable rhythm has also been attributed, in part, to improvements in diagnosis and treatment of structural heart disease.S2.2.2-40 Figure 1A. SCD incidence and total events.S2.2.2-1 EF indicates ejection fraction; and SCD, sudden cardiac death. Figure 1B. SCD and clinical subsets.S2.2.2-1 SCD indicates sudden cardiac death. CLINICAL STATEMENTS AND GUIDELINES 2.2.2. Population Subgroups and Risk Prediction Risk prediction for SCA and SCD is complex. Risk analy- sis is divided into 2 general categories: population risk prediction and individual risk prediction.S2.2.2-41,S2.2.2-50 Conventional epidemiological markers provide insight into probabilities for the development of ischemic heart disease within a general class of subjects, but ade- quately tested and validated profiles for SCA risk strati- fication of individuals in the general population do not presently exist. 