Amiodarone After Conversion From a Non-shockable to a Shockable Rhythm in Out-of-Hospital Cardiac Arrest A Propensity Score-Matched Analysis from the German Resuscitation Registry

Background Amiodarone should be administered after three shocks according the current ERC ALS guidelines. However, its effect in out-of-hospital cardiac arrest (OHCA) patients with an initial non-shockable rhythm who subsequently convert to a shockable rhythm is not established. Methods We performed a retrospective observational cohort study using data from the German Resuscitation Registry. Adult patients with non-traumatic OHCA, having an initial non-shockable rhythm and subsequently received at least two defibrillations were included. Propensity-score-matched patient pairs (1:1) were analysed to compare outcomes between patients who received amiodarone during resuscitation and those who did not. The primary outcome was survival to hospital discharge. Secondary outcomes included hospital admission with return of spontaneous circulation (ROSC), 24-hour survival, survival to hospital discharge, and favourable neurological outcome at hospital discharge. Results Of 5,535 patients included 3,181 received amiodarone and 2,354 did not. After propensity-score matching, 1,843 patients remained in each group. Amiodarone administration was associated with higher rates of hospital admission with ROSC (26.7% vs. 23.0%; OR 1.22, 95% confidence interval 1.05–1.42), 24-hour survival (21.4% vs. 14.7%; OR 1.58, 95% CI 1.33–1.87), and survival to hospital discharge (6.5% vs. 4.2%; OR 1.58, 95% CI 1.18–2.12). Favourable neurological outcome at hospital discharge was not statistically significant (3.7% vs. 2.9%; OR 1.31, 95% CI 0.91–1.89). Conclusions In OHCA patients with an initial non-shockable rhythm who subsequently converted to a shockable rhythm, amiodarone administration was associated with improved short-term and long-term survival, but not with a statistically significant improved favourable neurological outcome. Future controlled studies might define the proper (earlier) time of amiodarone administration.