This study utilises a randomized, double-blind trial involving 8014 patients with out-of-hospital cardiac arrest in the United Kingdom across five National Health Service ambulance services. The study findings report that, in adults with out-of-hospital cardiac arrest, the use of epinephrine resulted in a significantly higher rate of 30-day survival than the use of placebo. This is the largest study of its kind to date and has been described by The International Liaison Committee on Resuscitation (ILCOR) as ‘The landmark study of the past two decades’.