MonashHeart acting director and cardiologist Sujith Seneviratne said he was surprised by the findings. He said patients were warned about the risk of a second heart attack and it was standard practise to send them to cardiac rehabilitation where they would be educated.

"Perhaps we're not giving that message strongly enough," Dr Seneviratne said, ascribing the lack of knowledge to the fact that most patients felt almost normal very shortly after being treated for a heart attack.

"Once you actually treat that event, usually with either stenting or bypass surgery, within four weeks' time, they're pretty much back to their normal self.

"After a while they tend to forget about it and think the risk of another event is very small."

He said doctors might need to emphasise the risks of a repeat heart attack more strongly.