Initiatives for improving out-of-hospital cardiac arrest outcomes.

O ut-of-hospital cardiac arrest (OHCA) leading to sudden cardiac death (SCD) remains a huge public health burden, accounting for >350 000 deaths in the United States each year 1 and an equivalent number in Europe. The societal impact is evident from the fact that as many as 50% of all cardiac deaths are SCDs, 1 with many of the affected individuals in their productive years. One cost estimate places the financial burden on society at $33 billion per year in the United States, 2 including the cost of response systems, post–cardiac arrest hospitalizations , and long-term care of survivors. Long-term care includes rehabilitation, disability expenses, and medical costs specific to survivors such as implantable cardioverter-defibrillators. Attempts to address the OHCA/SCD challenge encompass 3 basic strategies: prediction, prevention, and intervention. Prediction remains a daunting challenge because 50% of SCDs are first cardiac events without specific forewarnings of unrecognized disease. Data on familial clustering of SCD as first cardiac events 4 suggest the possibility of genetic profiling of individual risk. However, other than the rare inherited arrhyth-mia syndromes, identification of genetic SCD risk markers with a large effect size remains a hope for the future. The numerically large problem associated with the common cardiac disorders dominates the public health burden. Atherosclerosis risk scoring methods provide some profiling capability for this most common cause, but they are largely not specific for cardiac arrest itself and have limitations for individual risk prediction. 3 Prevention is equally challenging. It depends on unrealized strategies for developing individual risk prediction models having small denominators and proportionally large numerators , in addition to cost-effective preventive therapies that provide high levels of efficiency. The latter is defined as high absolute risk reduction in an identified population subset that encompasses a substantial proportion of the event burden. 4–6 Only a small part of the prevention strategy is addressed by use of implantable cardioverter-defibrillators and other therapies in the identified high-risk subgroups such as the primary prevention of SCD in patients with low ejection fractions or heart failure and the rare inherited arrhythmogenic syndromes. However, the majority of OHCAs and SCDs occur among 3 lower-risk groups: the apparently normal general population, those with risk factors for atherosclerosis in the absence of recognized disease, and those with known disease that is profiled to be at low risk. Risk factor modification and treatment have had an impact on the expression of disease prevalence, …