The only realistic way to get someone back from ventricular fibrillation is cardioversion.

That's why automatic external defibrillators are in so many public spaces these days. If someone drops in your presence, you find that thing and get the pads on them ASAP. It won't shock if not indicated; it will tell you to resume CPR.

A former high school classmate of mine, who had played football with me from fifth grade on, dropped dead walking around in a bookstore at age 23. Almost certainly WPW.