What does a heart attack feel like and is it an agonising way to die?

I’m not asking about the symptons leading up to a heart attack – more about the actual heart attack itself.

Is it a pain on the left side or middle side of the chest, and what does it feel like and what other effects does it have (e.g. on breathing etc).

When we hear that people died of a heart attack, would this have been most likely an agonising experience, or would they simply have experienced some chest pain before a sudden loss of conciousness?