BLS? BLSD? DEPENDS

The defibrillator establishes which type of intervention, and whether to activate it, but the rescue chain and the speed of reaction are established by the people and their training.

When there is preparation, the training is repeated frequently, the simulations are realistic to the possible scenarios, the speed of intervention and alert lead to decisive results.
BRAVI GUYS and BRAVO CLAUDIO, and this inevitably refers to the recently published article referred to in the link