Expedited Conveyance of Out-of-Hospital-Cardiac Arrest patients with STEMI and shockable rhythms to Cardiac Arrest Centres - A Feasibility Pilot Study of the British Cardiovascular Intervention Society conveyance algorithm

Background and aims: Guidelines suggest non-traumatic out-of-hospital cardiac arrest (OHCA) be conveyed to cardiac arrest centres (CAC). We hypothesised that (a) a pre-hospital conveyance algorithm based on initial presenting rhythm following OHCA is feasible and (b) that would demonstrate survival advantage.

Methods: This observational pilot study included all consecutive patients with OHCA from suspected cardiac aetiology from the county of Essex, United Kingdom from April 2022-April 2023. For the first 6 months, OHCA patients had conveyance as standard of care. For the next 6 months, consecutive OHCA patients with STEMI or initial shockable rhythm were directly conveyed to the CAC, initial non-shockable rhythm without STEMI continued to be taken to the nearest Emergency Department (BCIS protocol). Primary outcome was death from any cause at 30 days. Secondary outcome was survival with favourable neurological outcome.

Results: Of 330 patients (mean age 67.5±13.1, 66% male), 162 patients were in the standard care group and 168 in the BCIS conveyance group. Algorithm implementation was associated with numerically lower all cause 30-day mortality [(81% vs 73%, RR 1.10 (95% CI 0.98-1.24) p=0.10] and numerically higher 30-day survival with favourable neurological outcome [15% vs 19%, RR 1.05 (0.95-1.15), p=0.38]. Post hoc analysis showed that the BCIS conveyance algorithm was associated with lower 30 day mortality in those with an initial shockable rhythm [(61% vs 41%, RR 1.5 (95% CI 1.05-2.13) p=0.02 and in those with a MIRACLE₂ score ≤5 [(63%% vs 38%, RR 0.59 (95% CI 0.61-0.86) p=0.005].

Conclusions: The BCIS algorithm is feasible and did not impact overall mortality, but there is signal that direct conveyance of OHCA patients with an initial shockable rhythm and low MIRACLE₂ score, to a dedicated CAC may improve survival.