Rhythm-specific association of epinephrine with outcomes in non-shockable cardiac arrest: a nationwide propensity-matched study.

BACKGROUND

Although current international guidelines strongly recommend uniform early epinephrine administration in out-of-hospital cardiac arrest (OHCA) patients with non-shockable rhythms, how the association between epinephrine and ROSC differs according to the initial rhythm remains unclear. The aim of this study was to investigate whether the association between epinephrine and return of spontaneous circulation (ROSC) differs between patients with asystole and those with pulseless electrical activity (PEA) and how this difference changes over time.

METHODS

We analysed adult OHCA patients with non-shockable rhythms registered between June 2014 and December 2021 in the Japanese Association for Acute Medicine's Out-of-Hospital Cardiac Arrest registry. Risk-set matching was performed using time-dependent propensity scores. We evaluated how the time-varying association between epinephrine and ROSC differed according to initial rhythm.

RESULTS

Among 58,977 patients, 42,161 had asystole and 16,816 had PEA. The association between epinephrine and ROSC differed by initial rhythm (interaction odds ratio [OR], 0.60; 95% confidence interval [CI], 0.51-0.68) at 5 min after emergency medical service contact, and this difference diminished over time. At the same time point, the OR of epinephrine for ROSC was 1.81 (95% CI, 1.57-2.07) in asystole and 1.43 (95% CI, 1.14-1.58) in PEA in subgroup analyses. A similar trend was observed for 30-day survival, whereas no significant difference was found regarding favourable neurological outcomes at 30 days.

CONCLUSIONS

The association between epinephrine and ROSC was greater in patients with asystole than in those with PEA, although a statistically significant association was observed in both groups.