Speed of MI symptom onset affects patients’ response

Author: Louise Prime

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People take several times longer to seek medical help for gradual-onset symptoms of myocardial infarction (MI) compared with rapid-onset heart attack symptoms even though both are a medical emergency and require urgent help, research has shown. The authors of the prospective study*, published in the European Journal of Cardiovascular Nursing, urged people to call an ambulance immediately if they have MI symptoms, however quickly or slowly they develop, to improve their prognosis.

The research team, led from Chicago in the US, analysed the time taken by 474 patients who had attended the emergency department of hospitals across four regions of the US, with acute coronary syndrome (myocardial infarction and unstable angina). They used data on symptom characteristics, and time from symptom onset to arrival in the emergency department, taken from these patients’ responses to the ACS Patient Information Questionnaire.

They reported that patients were roughly evenly split between those who had had rapid symptom onset (56%) and those whose symptoms had emerged gradually (44%). The median time between symptom onset and seeking medical help was four hours, but they found that this varied considerably depending on speed of symptom onset, for both women and men. On average, people with abrupt symptom onset had sought medical help within 2.6 hours, compared with more than eight hours for those with gradual symptom onset.

The researchers also found that arrival by ambulance was associated with a shorter interval between the start of pain and hospital arrival. However, only 45% of patients called an ambulance, while more than half (52%) had used their own transport and 3% were transferred from another hospital; longer delays were also more likely among uninsured patients.

They added that among men with abrupt symptom onset and a diagnosis of ST-elevation myocardial infarction (STEMI), which requires rapid restoration of blood flow to blocked arteries, in more than half (54%) of cases their symptoms were triggered by exertion such as climbing stairs, pulling, pushing, shovelling, heavy gardening, running, and jogging.

The study authors pointed out that previous research has shown that a maximum delay of two hours from symptom onset is recommended to achieve fast treatment and the best outcomes – and that serious complications and death are more likely beyond this window.

They commented: “Both [gradual and rapid onset symptoms] are a medical emergency and require urgent help. But our study shows that gradual symptoms are not taken seriously.

“Nearly half of patients had a slow onset, so this is not uncommon. The symptoms of acute coronary syndrome are non-specific, and interpretation is often challenging for patients. Chest pain, chest discomfort, and chest pressure are warning signs that an artery may be blocked, and patients should call the emergency medical services immediately.”

They said: “Men with ischaemic heart disease or with multiple risk factors such as hypertension, diabetes, high cholesterol, or family history of heart disease should be aware that chest pain or discomfort after physical effort could be a heart attack.

“Chest pain or discomfort, whether severe and sudden or mild and slow, should not be ignored. Symptoms can also include pain in the throat, neck, back, stomach or shoulders, and may be accompanied by nausea, cold sweat, weakness, shortness of breath, or fear. Call an ambulance straight away; the sooner you get help, the better your prognosis.”


*Mirzaei S, Steffen A, Vuckovic K, et al. The association between symptom onset characteristics and prehospital delay in women and men with acute coronary syndrome. Eur J Cardiovasc Nurs. 2019. doi:10.1177/1474515119871734.

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