In the classic coloumn Can someone be literally scared to death? - The Straight Dope from 2006 there’s a reference to a British four-year old child being scared to death at dentist visit.
Is there an online reference for that report?
If the question is can some1 young & healthy be scared to death, I present this:
The Big Red One is a semi-autobiographical book later made a movie with Lee Marvin & Mark Hamill, written by Sam Fuller - a ww2 veteran soldier in the 1st Division. Among many stories was a prolonged German artillery attack which when it stopped, the sergeant ordered his men up out of foxholes. All but 1 got up. The sergeant checks the pulse on his neck, possibly feels the chest for heartbeat while 1 of his incredulous squad guys says ‘he’s not even hit; not a scratch on him’. Sergeant goes ‘it’s not the 1st time a dogface dropped dead from a heart attack; I’ve seen it before’, and they move on. Technically what likely happened was the fear itself or maybe adrenaline triggered ventricular fibrillation instead of the classic blocked-artery-cuts-off-bloodflow-so-heart-muscle-dies scenario ‘heart attack’, but the main point is what Fuller [thru the character, sergeant] says is absent any external trauma, an otherwise healthy young man can indeed be scared to death. Fuller in an interview swore that while not every single line of dialog from his 3 years in ww2 is accurately remembered, the events he wrote about all happened. All else aside, the book and movie are epic, showing things not covered in History class [German kid soldiers, French soldiers riding camels and horses & acting as cavalry assaulting a tank, Italian Fascist brutality, etc.].