Expedited transfer to Emergency Department versus Cardiac Catheter Laboratory in a Cardiac Arrest Centre for non ST-elevation Out-Of-Hospital Cardiac Arrest: ARREST Trial as-treated analysis.

Background: The ARREST trial demonstrated that in adult patients, transfer to a cardiac catheter laboratory in a cardiac arrest centre (CAC) following resuscitated out-of-hospital cardiac arrest (OHCA) without ST-elevation did not reduce deaths at 30 days compared with delivery to the geographically closest emergency department (standard care). More than half of the CACs had a co-located emergency department to which patients were delivered as part of the standard care arm, which may have influenced outcomes.

Aim: We performed a pre-specified as-treated analysis to determine if a CAC and the location patients were delivered to, either emergency department or cardiac catheter laboratory, reduced deaths.

Methods: Patients (aged ≥18 years) with resuscitated OHCA without ST elevation who were enrolled in the ARREST trial were grouped according to the location they were to delivered to- either an emergency department with or without a co-located CAC or a cardiac catheter laboratory within a CAC - at one of 32 hospitals in London, UK - by London Ambulance Service irrespective of randomised allocation. The as-treated population were therefore analysed as one of three groups: 1) emergency department in a CAC 2) direct to a cardiac catheter laboratory in a CAC and 3) emergency department in a non-CAC. The primary outcome of the trial was all-cause mortality at 30 days. Secondary outcomes included all-cause mortality at 3 months and neurological outcome at discharge and 3 months. A pre-specified analysis adjusting for age, sex, initial shockable rhythm, witnessed cardiac arrest, bystander CPR, the time from cardiac arrest until ROSC, and location of cardiac arrest was performed in the as-treated groups.

Results: Between January 15, 2018 and December 1, 2022; a total of 862 participants were enrolled into the trial. Data for the primary outcome for this analysis were available in 818/862 (94.9%). Patients delivered to an ED in a CAC had fewer deaths at 30 days compared with the ED in a non-CAC group (83/182, 45.6% versus 178/233, 76.4%; adjusted OR 0.43, 95% CI 0.24 to 0.76; P=0.0039). Patients delivered to a cardiac catheter laboratory in a CAC also had fewer deaths compared with the ED in a non-CAC group but there was no statistical difference (250/403, 62.0%: adjusted OR 0.72, 95% CI 0.44 to 1.18; P=0.19). Survival with a favourable neurological outcome at hospital discharge occurred in 88/177 (49.7%) of the ED in a CAC group, 130/406 (32%) of the catheter laboratory in a CAC group and 42/228 (18.4%) of the ED in a non-CAC group.

Conclusions: In this as-treated analysis of the ARREST trial, in adult patients with resuscitated OHCA without ST-elevation, we observed a lower 30-day mortality and favourable neurological outcomes following delivery to an ED in a CAC and cardiac catheter laboratory in CAC, when compared with delivery to ED in a non-CAC.