(242) Risk of Arrhythmia With Epinephrine Versus Norepinephrine After Out-of-Hospital Cardiac Arrest

Introduction: Bolus doses of epinephrine during cardiac arrest increase cardiac perfusion via alpha-adrenergic arteriole constriction and thus increase the chance of obtaining return of spontaneous circulation (ROSC). Post cardiac arrest, however, the beta-adrenergic effects of epinephrine can cause myocardial dysfunction, tachyarrhythmias, and re-arrest after ROSC. The optimal management of post-resuscitative shock in out-of-hospital cardiac arrest (OHCA) is unclear. The objective of this study is to determine the rates of clinically significant tachyarrhythmias in OHCA patients who receive continuous epinephrine versus norepinephrine infusion for post-resuscitative shock after ROSC.

Methods: This was a retrospective cohort study of adult patients admitted for OHCA with post-resuscitative shock managed with either epinephrine or norepinephrine infusions within 6 hours of ROSC. The primary outcome was incidence of clinically significant cardiac tachyarrhythmias. The secondary outcomes were subsequent cardiac arrest during hospital admission and in-hospital mortality.  Multivariable analyses were performed after adjustment for age, presenting rhythm, history of cardiac arrhythmias, targeted temperature management, dose of vasopressor, and if any anti-arrhythmic medications were used within the first 6 hours after ROSC.

Results: Between May 5th, 2018, to January 31st, 2022, there were 221 patients admitted who met inclusion criteria. There was no difference in the rate of tachyarrhythmias between epinephrine and norepinephrine infusion in univariate (47.1% vs 41.7%, OR 1.24, 95% CI 0.71-2.20) or multivariable analysis (OR 1.34, 95% CI 0.68-2.62). Patients treated with epinephrine were more likely to have re-arrest during hospitalization (OR 5.77, 95%CI 2.74- 12.18, p< 0.001) and had higher in-hospital mortality than those treated with norepinephrine (OR 6.21, 95% CI 2.37-16.25, p< 0.001).

Conclusions: There was no difference in clinically significant tachyarrhythmias in OHCA patients treated with epinephrine versus norepinephrine infusions after ROSC. Re-arrest rates and in-hospital mortality were higher in patients who received epinephrine infusions. Results of this study add to the literature suggesting norepinephrine as the vasopressor of choice in OHCA patients with post-resuscitative shock.