I would say that in a sense it's possible. Think of it this way. A heart attack can be caused by a sudden scare or something very severe. This could happen as a result of something that happened in a dream.

I know I, for example, sometimes wake up in the middle of the night due to a nightmare or whatever. This shows me that it is definitely possible to have something severe happen in a dream being that I actually remember it.

Technically the dream itself wouldn't kill you, it'd be the heart beat or whatever that is caused from it.

That's my view,