Calling an ambulance at the first sign of a heart attack increases the chances of survival by 50 per cent, the Irish Heart Foundation has said.
The foundation said some 6,300 people suffer heart attacks in Ireland annually but only half of these will go to hospital by ambulance.
"If you get to hospital within an hour, you have a 50 per cent higher chance of survival," Dr Angie Brown, medical director of the Irish Heart Foundation said.
Dr Brown was speaking at the launch of an Irish Heart Foundation awareness campaign aimed at middle aged men who are being urged not to be embarrassed to call an ambulance when they feel ill.
She said symptoms of a heart attack included sweating, nausea or light-headedness, not just the more dramatic symptoms people might imagine.
Westlife member Nicky Byrne said he was involved in the awareness campaign to commemorate his father, Nicky Byrne snr, who suffered a fatal heart attack two years ago at the age of 60.
"He wasn't feeling well and like many men, he didn't want to cause a fuss," Mr Byrne said. "We now know he was having a heart attack."
He said the Byrne family hoped the campaign would also raise awareness of heart disease among young people.