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Impact of bystander-initiated cardiopulmonary resuscitation for out-of-hospital cardiac arrest: where would you be happy to have a cardiac arrest?

Approximately 275 000 out-of-hospital cardiac arrests (OHCAs) occur in Europe every year with an incidence of 38 emergency medical services (EMS)-treated events per 100 000 person-years. Survival after cardiac arrest still remains low, but in several countries and regions, public health initiatives to improve bystander-initiated cardiopulmonary resuscitation (CPR) and defibrillation, in conjunction with intensive care management advances, have recently resulted in significantly improved outcomes. Indeed, although the observed mortality decrease probably has multifactorial reasons and should be considered a result of the enhancement in each component of the ‘chain of survival’, accumulated high-quality evidence from large-scale registries indicates that bystander CPR can be a lifesaving intervention and the cornerstone of resuscitation from OHCA. Regardless of the associated earlier recognition of the event and faster attendance of EMS, high-quality bystander CPR can guarantee an adequate haemodynamic support and prolong the time window for defibrillation in shockable rhythm cardiac arrests. Overall, bystander CPR before EMS is associated with short-term survival two to three times higher than for patients who do not receive CPR before arrival of EMS. In addition, the benefits of bystander CPR can also translate into a higher probability of absent or minimal brain damage in survivors of cardiac arrest. The location where cardiac arrest occurs is among the critical prognostic factors. Cardiac arrest at home is associated with a mortality at least three times higher than for those which occur in public locations, probably as a consequence of the lower probability of a witnessed event, lower likelihood of high-quality CPR, less favourable clinical characteristics of subjects, and limited access to defibrillators before the arrival of EMS personnel. In this issue of the European Heart Journal, Sondergaard and colleagues describe temporal changes in bystander-initiated CPR for OHCA according to public or residential location and explore differences in the corresponding shortand long-term outcomes. A total of 25 505 first-time OHCAs occurring from 2001 to 2014 were included in the nationwide Danish Cardiac Arrest Registry, and the proportion of events occurring in residential locations (73.6%; n = 18 767) was higher than those occurring in public (26.4%, n = 6738). The application of national initiatives and mandatory educational programmes during the study period produced a remarkable increase in the proportion of patients receiving bystander-initiated CPR in both residential and public locations, from 16.0% to 61.0% and from 36.4% to 83.1%, respectively. In the same time period, significant improvements in 30-day survival were observed in both residential and public locations, from 2.9% to 10.0% and from 6.4% to 25.2%, respectively, and these results were maintained at 1-year follow-up. Of note, though significantly lower than in patients who received bystander-initiated CPR, 30-day and 1-year survival improved throughout the study period both in public and in residential locations even in patients who did not receive bystander-initiated CPR, as a possible consequence of the simultaneous therapeutic advances occurring over time. Among 2348 patients surviving at least 30 days after cardiac arrest, the incidence of brain damage or nursing home admission significantly decreased throughout the study period in public cardiac arrests only—from 18.8% to 6.8% (Ptrend < 0.001), while there were no significant changes during the study period in residential cardiac arrests. A similar pattern was observed in terms of survival, with