Point-of-care testing for pre-hospital stratification after out-of-hospital cardiac arrest: the RAPID-MIRACLE study

Out-of-hospital cardiac arrest (OHCA) has high mortality, and outcomes remain heterogeneous despite guidelines recommending universal conveyance to cardiac arrest centres. Early pre-hospital risk stratification may identify patients most likely to benefit. The pre-hospital utility of MIRACLE2 is unknown, so we evaluated the feasibility of rapid point-of-care testing to enable calculation of the MIRACLE2 score after return of spontaneous circulation (ROSC).

RAPID-MIRACLE was a prospective, multi-centre observational study conducted across London with the London Ambulance Service. Adult patients with suspected cardiac aetiology OHCA achieving sustained ROSC were enrolled. Pre-hospital point-of-care venous blood-gas sampling was performed with results blinded to receiving hospitals. We evaluated ROSC-MIRACLE2 incorporating post-ROSC pH, compared with a modified MIRACLE2 excluding pH (pre-MIRACLE2) and standard MIRACLE2 calculated on hospital admission. The primary outcome was poor neurological outcome at 30 days, defined as cerebral performance category (CPC) 3-5. Among 292 patients, 48% had poor neurological outcome. ROSC-MIRACLE2 demonstrated excellent discrimination [area under the receiver operating characteristic curve (AUC) 0.89 (95% CI 0.85-0.92)], comparable to pre-MIRACLE2 [AUC 0.88 (95% CI 0.84-0.92)], and admission MIRACLE2 [AUC 0.89 (95% CI 0.85-0.92)]. For ROSC-MIRACLE2, a threshold 0-2, the negative predictive value for good outcome was 0.89 (0.82-0.94). At a threshold ≥5, the positive predictive value was 0.88 (0.82-0.94). In a multi-variable regression model, post-ROSC pH was independently associated with poor neurological outcome and less than 3% of patients with a ROSC pH <7.00 had good neurological outcome.

In this study, pre-hospital application of ROSC-MIRACLE2 enables early neurological risk stratification following resuscitated OHCA. Point-of-care pH improves prognostic precision, but is constrained by feasibility, whilst the simplified pre-MIRACLE2 score is more practical with comparable performance. Integration into OHCA care pathways may improve patient stratification and resource utilization but requires further study.