Importance of immediate bystander life support on short and long-term survival of patients with out-of-hospital cardiac arrest and myocardial infarction

Out of hospital cardiac arrest (OHCA) during ST-elevation myocardial infarction (STEMI), is a time-dependent emergency associated with elevated mortality. Quick and effective links of the survival chain, increases survival probability. Over the time, the contribution of links diminishes since patients dye at each phase and the percentage of patients progressing ahead the survival chain quickly fall. Therefore, the first two components of the survival chain are crucial for rapid return of spontaneous circulation (ROSC) and survival. More specifically, an immediate bystander life support (BLS:quick recognition,EMS call, starting cardiopulmonary resuscitation(CPR) and AED use)) has utmost importance. Despite these notions initiation of BLS by layperson bystanders is low.

In setting of OHCA during STEMI, we aimed to assess if the percentage of layperson initial rescuers has changed over time. Further, we sought to explore if there are differences according to initial rescuers on ROSC time, on in-hospital and long-term outcome.

Among 3315 patients with STEMI, admitted in Italy, between 2003-2024, 172(5.2%) had OHCA.

The mean age was 63(12) years and 80% were male. In total, 58% of patients presented with an anterior STEMI and 31% had 2 or more comorbidities. Of 172 OHCA patients, 44(26%) were initially rescued by a layperson. We found that over the years, the percentage of initial layperson BLS is constantly increasing (p<0.01;Fig.1a).

The median time to ROSC was 10(1-20) min. Longer ROSC were observed when layperson initiated BLS compared to EMS (20(12-28) Vs. 5(0-18)min, p<0.01; Fig.1b). Patients in whom layperson, initiated BLS more frequently underwent IOT compared to EMS (40(91%) Vs. 78(65%), p<0.01). Of 44(25.6%) patients who died during hospital stay, we did not found difference according to the type of initial rescuer (p=0.52;Fig.1c); compared to survivors, patients who died were older (p<0.01), had worse left ventricular ejection fraction (LVEF) (p<0.01) and had more comorbidities (diabetes mellitus (p=0.01), dyslipidemia (p=0.03) and chronic kidney disease (p=0.01)). On logistic regression analysis, worse LVEF (OR 1.38,p=0.02), longer time to ROSC (OR 1.38,p<0.01) and older age (OR 1.46,p=0.01) were predictors of in-hospital mortality, after correction for according rescuer type.

During a median follow-up of 7 years, 18 (14%) patients died; long-term outcome did not differ according to the initial type of rescuer (p=0.76;Fig.1d).

Over time, layperson initial rescuers constantly increased. Rapid ROSC was crucial factor for in-hospital survival, independently of the initial rescuer type. Also, similar long-term survival was observed comparing patients with initial layperson or EMS BLS.

Our data highlights the importance of immediate resuscitation and underlines the importance to promote population awareness and BLS training to further improve survival after OHCA.

Open in new tabDownload slide