Trained personnel? If they were capable of reading the instructions that were in the case, or listening to the directions spoken by the machine, that covers about 95% of what training is really required for a normal adult.
I am a certified First Aid/CPR/AED instructor for the American Red Cross. The level of training required to use an AED if you are calm, cool, and collected (and no cross-chest nipple piercings are involved) is less than is necessary to assemble a table from Ikea. That said, when you need to use one, calm, cool, and collected are frequently out the window, which is why training is recommended. Almost anything you can do wrong, the machine will let you know that something is wrong so you can correct it. Many kits even come with a razor to deal with the overly hirsute. Oh, and I was involved with building an internal pacemaker capable of phoning home to the doctor (though you had to hold the phone up to your chest, it couldn't reach out and grab it) back when they still required DSPs.
The AEDs automatically analyze heart rhythms (or lack thereof) and notify the operator to push a button if a shock is required. They will provide a shock for two different rhythms- V-fib (Ventricular Fibrillation) and V-Tach (Ventricular Tachychardia). They will not shock for asystole (no electrical heart signals detected at all, and must be avoided so you don't try using an AED to jump start your car or do some tiny welding) and PEA (pulseless electrical activity- the wiring is working, but the engine is dead).
Long story longer: Heart Attacks are NONE of these cases. AEDs WILL NOT PRODUCE A SHOCK for a heart attack, which is simply the blockage of blood to the heart, usually caused by a clot breaking loose. Heart attacks can result in cardiac arrest, which does result in one of the four cases above, but an AED will do nothing for a simple heart attack. TFA correctly describes that he had a cardiac arrest (sudden dropping to the ground), but incorrectly says he flat-lined (asystole, AED wouldn't have helped in that case) and that he had a heart attack (if he only had a heart attack, he could have walked off the court and hopefully gotten a quick ride to a hospital).
Any more info needed? I strongly encourage you and everyone to take a First Aid/CPR/AED class from whatever qualified source is available (Red Cross, Heart Association, etc). The chance that you will ever need to perform CPR is pretty low, but I have had to deal with a choking in a restaurant, a compound fracture at a swimming pool, a petite mal siezure on a subway, and other situations that are far more likely.