My Husband Had A Stint After A Heart Attack About

My husband had a stint after a heart attack about five or six years ago. Last night he woke around 3 a.m. with pain mid chest to the right side. He said he had an odd taste in his mouth, and a bit of nausea. Could his stint be failing? He said the taste in his mouth is a metal taste. Right now (after 12 hours) the pain (he said was 3 of 10) is subsiding. Pain now less than 3 out of 10, but it has not ceased.