Abstract

BACKGROUND: Amiodarone is used in shockable out-of-hospital cardiac arrest (OHCA), but the ideal dose is unknown. METHODS: This was an analysis from the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registry (2011-2015). Patients with shockable OHCA who received 5 or more defibrillation attempts and treatment with 300 or 450 mg of amiodarone were included. Outcomes were ROSC at ED arrival, survival at hospital discharge, and favorable neurologic function at discharge. Group-differences were adjusted for using inverse probability weighting and a multiple logistic regression model. RESULTS: The present study included 910 patients; 426 received amiodarone 300 mg and 484 received amiodarone 450 mg. The amiodarone 300 mg group had a higher estimated probability of ROSC at ED arrival as compared with the amiodarone 450 mg group (30.8% [95% CI, 26.6-35.1] vs 24.2% [95% CI, 20.5-27.9], respectively; adjusted probability difference, 6.6% (0.9-12.3), p = 0.0234). The group differences in survival at hospital discharge (21.3% [95% CI, 17.2-25.4] vs 18.0% [95% CI, 14.6-21.5]; adjusted probability difference, 3.3% [-2.3-8.8]) and favorable neurologic outcome at discharge (16.5% [95% CI, 12.9-20.2] vs 12.7% [95% CI, 9.5-16.0]; adjusted probability difference, 3.8% [95% CI, -1.2-8.7]) did not reach statistical significance. CONCLUSION: In patients with shockable OHCA who received 5 or more defibrillation attempts, a dose of amiodarone 300 mg was associated with a similar survival compared with a total dose of amiodarone 450 mg. Further study is needed to evaluate the need for a second administration of amiodarone in patients with shockable OHCA.