Previous case reports and animal studies have suggested a possible role for naloxone in cardiac arrest even in the absence of opioid overdose.
Possible mechanisms include reducing the myocardial depressant effect of endogenous opioids, stimulating catecholamine release, and providing antiarryhthmic effects through an effect on cardiomyocyte ion channels.
A retrospective review of 32,544 out of hospital cardiac arrests over 5 years revealed 36 to have received pre-hospital naloxone. Of these, only one survived to hospital discharge, who tested positive for opiates in a urine toxicology screen in the emergency department.
No need to change the guidelines yet then.
Naloxone in cardiac arrest with suspected opioid overdoses
Resuscitation. 2010 Jan;81(1):42-6