攸关

of great concern

distant, far / adverbial prefix

mountain pass / to close; to shut; to turn off / to confine; to lock (sb) up; to shut (sb in a room, a bird in a cage etc) / to concern; to involve

matter of life and death

vitally important / a matter of life and death

a make-or-break matter / a matter of life and death

to be of vital interest