MANY people who suffer a heart attack do not seek help on time because they do not fit the classic "Hollywood style" depiction of someone clasping their chest in pain.
Researchers at Trinity College Dublin examined how 900 heart attack patients in five hospitals responded at the first onset of symptoms.
The study, published in the 'Journal of Emergency Medicine', found that 65pc experienced "slow-onset" warning signs – such as chest and left arm discomfort, shortness of breath and tiredness – rather than intense chest pain, tightness and discomfort.
Those whose symptoms were more vague were more likely to mistake the signals and delay seeking treatment – which can prove fatal.
Ideally treatment should be given within an hour but it can be administered within two hours.
But the study found that those with slow-onset symptoms were delaying seeking treatment by an average of three-and-a-half hours.
Dr Sharon O'Donnell, director of undergraduate teaching and learning at Trinity's School of Nursing and Midwifery, said: "For many years we have tried to reduce pre-hospital treatment delays in patients experiencing heart attacks.
"Most people expect a heart attack to be associated with sudden, severe and continuous chest pain. However, the most surprising finding for us was that for the majority of people in our study, their heart attack started off with mild or intermittent symptoms, such as chest and left arm discomfort, shortness of breath and fatigue".
She said they found only one in three participants in the study suffered more dramatic pain.
"Whether a patient suffered slow-onset or fast-onset symptoms directly influenced the length of time it took patients to get to an emergency department or treatment by paramedics.
"Patients who experienced slow-onset took on average of 1.5 hours longer to arrive at the emergency department of a hospital than those with fast-onset symptoms," she added.
She pointed out that those who are slow in seeking help can significantly impact on their chances of survival and potential damage to the heart muscle.
"The quicker treatment is received the greater the benefits for the patient. The slow-onset heart attack patients in this study, the majority group, had an average of a three-and-half hour pre-hospital delay compared with a two-hour delay for the fast-onset patient cohort."
She said it was important to educate people that most heart attacks started with slow-onset symptoms, which can intensify.
"Future educational campaigns must dispel the myth that heart attacks always occur in a dramatic fashion. If someone experiences any worrying symptoms which are unresolved with rest or usual cardiac medication, then they should call an ambulance and go to hospital immediately."
Doctors also need to be more aware that most heart attacks have a slow-onset, the study warned.