yes it is.
caffeine is very dangerous. even for a healthy heart, to much at once can cause an attack.
plus it dehydrates you very quickly.
from only 7 energy drinks? bisjac please
the lethal dose for caffeine is 192 mg per kg
assuming a weight of 40 kg, that's about 8000 mg
exact caffeine numbers for four loko haven't been released, so let's highball it and do 300 mg
7 times 300 is 2100. that's a fourth of the lethal dose and wouldn't cause someone to drop dead on the spot