Correct - most AED's will only shock if they detect ventricular fibrillation (VF), or ventricular tachycardia (VT) above a certain rate. As a paramedic I have done dozens of cardiac arrests , asystole (flatline), VF, VT, etc. If the AED did not recommend a shock then it is likely the patient was in Asystole or pulseless electrical activity consistent with exanguination, asthma, tension pnuemothorax etc. In an asystole arrest CPR ,ventilation and IV adrenaline are the priorities. As deadhead said , sometimes adrenaline will change the cardiac rhythm to one that can be defibrillated. In all the Asystole arrests I have done only 1 has walked out of hospital and that was because the response time was less than 2 minutes, CPR was in progress when we arrived and he was young enough. It was a narcotic overdose. We get plently that we restore cardiac output on via adrenaline , defibrillation and a few other drugs but nearly always they die later in hospital from hypoxic brain injuries. By the way - I will be interested to hear if it actually was a choking. Arresting patients usually have a short convulsion caused by hypoxia to the brain. It is often appears as if the patient is choking. The poor guy had a fairly significant underlying cardiac history with chronic heart valve problems so this is what might have killed him.