Validation of the MIRACLE₂ Score for Prognostication After Out-of-hospital Cardiac Arrest

Background: Out-of-hospital cardiac arrest (OHCA) is associated with very poor clinical outcomes. An optimal pathway of care is yet to be defined, but prognostication is likely to assist in the challenging decision-making required for treatment of this high-risk patient cohort. The MIRACLE 2 score provides a simple method of neuro-prognostication but as yet it has not been externally validated. The aim of this study was therefore to retrospectively apply the score to a cohort of OHCA patients to assess the predictive ability and accuracy in the identification of neurological outcome. Methods: Retrospective data of patients identified by hospital coding, over a period of 18 months, were collected from a large tertiarylevel cardiac centre with a mature, multidisciplinary OHCA service. MIRACLE 2 score performance was assessed against three existing OHCA prognostication scores. Results: Patients with all-comer OHCA, of presumed cardiac origin, with and without evidence of ST-elevation MI (43.4% versus 56.6%, respectively) were included. Regardless of presentation, the MIRACLE 2 score performed well in neuro-prognostication, with a low MIRACLE 2 score (=2) providing a negative predictive value of 94% for poor neurological outcome at discharge, while a high score (=5) had a positive predictive value of 95%. A high MIRACLE 2 score performed well regardless of presenting ECG, with 91% of patients receiving early coronary angiography having a poor outcome. Conclusion: The MIRACLE 2 score has good prognostic performance and is easily applicable to cardiac-origin OHCA presentation at the hospital front door. Prognostic scoring may assist decision-making regarding early angiographic assessment.