A retrospective 'target trial emulation' comparing amiodarone and lidocaine for adult out-of-hospital cardiac arrest resuscitation.

Objective: The administration of amiodarone or lidocaine is recommended during the resuscitation of out-of-hospital cardiac arrest (OHCA) patients presenting with defibrillation-refractory or recurrent ventricular fibrillation or ventricular tachycardia. Our objective was to use 'target trial emulation' methodology to compare the outcomes of patients who received amiodarone or lidocaine during resuscitation.

Methods: Adult, non-traumatic OHCA patients in the ESO Data Collaborative 2018-2023 datasets who experienced OHCA prior to EMS arrival, presented with a shockable rhythm, and received amiodarone or lidocaine during resuscitation were evaluated for inclusion. We used propensity score matching (PSM) to investigate the association between antiarrhythmic and outcomes. Return of spontaneous circulation (ROSC) was the primary outcome. Secondary outcomes included the number of post-drug defibrillations and survival to hospital discharge.

Results: After application of exclusion criteria, 23,263 patients from 1,707 EMS agencies were eligible for analysis. Prior to PSM, 6,010/20,284 (29.6%) of the patients who received amiodarone and 1,071/2,979 (35.9%) of the patients who received lidocaine achieved prehospital ROSC. Following PSM, lidocaine administration was associated with greater odds of prehospital ROSC (36.0 vs. 30.4%; aOR: 1.29 [1.16, 1.44], n=2,976 matched pairs). Lidocaine administration was also associated with fewer post-drug defibrillations (median: 2 [0-4] vs. 2 [0-6], mean: 3.3 vs. 3.9, p<0.01, n=2,976 pairs), and greater odds of survival to discharge (35.1 vs. 25.7%; OR: 1.54 [1.19, 2.00], n=538 pairs).

Conclusion: Our 'target trial emulation' suggested that lidocaine was associated with greater odds of prehospital ROSC in comparison to amiodarone when administered during resuscitation from shock refractory or recurrent VF/VT.