Most people who suffer a heart attack do not experience the expected ‘Hollywood' style fast-onset of symptoms and so many delay seeking medical help, a major new Irish study has found.

Researchers looked at the type of symptoms experienced by almost 900 patients who suffered heart attacks, as well as the length of time it took them to attend five different Irish hospitals.

They found that two in three heart attacks involved what is known as slow-onset ACS (acute coronary syndrome). This refers to symptoms that are slower, milder and more intermittent than the classic symptoms many people expect.

In fact, just one in three people suffering a heart attack experienced fast-onset ACS, which is characterised by a severe and sudden onset of symptoms such as chest pain and feelings of tightness.

The study found that whether a patient experienced slow or fast-onset symptoms had a major impact on the length of time it took them to seek emergency treatment.

Those who experienced slow-onset symptoms took an average of 90 minutes longer to attend an emergency department (ED) compared to those with fast-onset symptoms. Furthermore, many of these patients phoned or visited their GP first. Those with fast-onset symptoms were more likely to phone the emergency services.

Meanwhile, just one in three people with slow-onset symptoms travelled to hospital by ambulance compared to half of those with fast-onset symptoms.

The researchers from the School of Nursing and Midwifery in Trinity College Dublin concluded that perceptions and expectations of symptoms have a major role to play when it comes to delays in seeking treatment for heart attacks. Patients expect a fast onset of symptoms and if this does not occur, they may assume they are not suffering a heart attack.

The researchers emphasised that delays in treatment can have a major impact on a patient's outcome. If someone is suffering a heart attack, they should receive life-saving medical treatment within two hours, although within one hour is ideal.

However in this study, the patients with slow-onset symptoms had an average of a three-and-a-half hour delay in getting to hospital compared with a two-hour delay for people with fast-onset symptoms.

"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," explained the study's lead author, Dr Sharon O'Donnell.

She said that it is essential that people are educated about the fact that ‘most heart attacks start with the slow onset of symptoms, which may later 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," she insisted.

She added that doctors also need to be ‘equally vigilant for the milder and slower onset of heart attack symptoms'.

This study, which was funded by the Health Research Board, is published in The Journal of Emergency Medicine.

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