The vast majority of crime where police should be involved are crimes where the victim can call the police later. For those that don't fit this criteria, either police patrols are already ineffective (targeted assassinations, for example), or the police isn't being called because the victim thinks it will make the situation worse. Which in many cases is true, and I think fixing that problem would be a good step to take.
That is not what occurred in practice and there is no data to suggest this would ever be a probable outcome. At any rate people don’t have a choice on who responds if the call is to 911.
The data behind 911 Good Samaritan laws[1] that protect people from being arrested when they call in overdoses would like to have a word with you.
[1] https://www.shatterproof.org/advocacy/state-by-state-informa...
In any case, if you are giving anyone defibrillators and locating them to minimize response time to cardiac incidents, it would be absurd to give it to the police.