Surprised to be evacuated from my cabin at 1 am because of helicopter picking up a heart attack victim.  Evidently they evacuate certain portions of several floors in the event helicopter hits ship???? We were enroute to Ensenada but they sped back toward San Diego...pretty amazing how efficiently they lowered basket, lifted and left.  Was a crew member and captain thanked ship next am for saving his life...was in ICU in San Diego.  More surprising was the fact that Princess gave everyone who had to leave their cabin a $50 credit for their inconvenience.  I assume it is the coast guard or navy that does Medivac...whoever it was very impressive