It is possible to die of fright because fright causes so much calcium to flood into the heart fibres that they seize up completely. Blood rushing through narrowed vessels generates shear forces against vulnerable cholesterol plaques adhering to the walls of the vessels. The resulting debris can cause a clot and block blood flow to the heart muscle.
Accounts of death from fear are widespread in the anthropological literature. In many primitive cultures a curse from a sorcerer or medicine man is believed to be sufficient to kill a person. The death is usually slow and lingering although sudden death is also known.
Animals can also be frightened to death, as was demonstrated in the 1950s and 1960s in which experiments on animals were undertaken to determine whether this was possible.
Although such death has been considered restricted to superstitious primitive societies, it is now held to be possible that it might be to some degree responsible for deaths by heart attack. The more common types of heart attack can also be triggered by fear. If this only applied to a small percentage of the millions of deaths by heart attack, it would still be a significant public health threat.