About 60 000 people have an out-of-hospital cardiac arrest (OHCA) in the UK each year.1 Frustratingly, despite major advances in medical technology only around 8% of patients admitted to hospital survive to discharge;2 furthermore, around a half of survivors have significant cognitive impairment.3 ,4 Identifying which patients are likely to survive and then which survivors are most likely to enjoy a reasonable quality of life is a major clinical challenge, particularly when attempting to make an assessment in the emotionally charged circumstances of an emergency admission.

OHCA encompasses a broad spectrum. Most patients have an unwitnessed arrest without early bystander cardiopulmonary resuscitation (CPR) and an initial non-shockable rhythm (pulseless electrical activity or asystole). The outcome in this group is very poor, with <2% surviving to discharge, and only 0.6% having a good neurological outcome.5 Better outcomes are seen in patients with a witnessed cardiac arrest who receive early bystander CPR and DC shock for ventricular arrhythmia. About one in five of such patients survive to hospital discharge.5 The best outcomes are seen in patients who regain consciousness before arriving at hospital and have ST elevation on …