Not Recognizing Slow-onset Heart Attacks Leads to Dangerous Delays in Seeking Medical Treatment

Prompt medical care is necessary for the effective treatment of heart attacks, as well as best possible health outcomes and the least risk of mortality. A major factor in determining the speed with which a heart attack receives medical attention is the accurate and rapid interpretation of heart attack symptoms. However, not all heart attacks resemble the sudden cardiac events depicted in television and movies. In contrast to “Hollywood-style” fast-onset heart attacks, many heart attacks are slow onset in nature. These slow-onset heart attacks don’t present symptoms consistent with what patients expect a coronary event to entail (chest pain that is sudden, continuous, and severe); their symptoms may not be associated with a cardiac cause. Misinterpretations of the symptoms of slow-onset heart attacks can delay the decision to receive prompt medical attention, which in turn may lead to heart attack sufferers not receiving the full possible benefits of life-saving reperfusion therapies.

With a slow-onset heart attack, a number of different main symptoms may present themselves, both typical and atypical. In addition, the onset of a slow-onset heart attack is gradual; the symptoms may present themselves intermittently, and the symptoms are mild before possibly gradually intensifying.

A recent study by researchers at Trinity College compared the factors that contributed to delays in seeking hospital treatment for 577 slow-onset heart attack patients and 327 fast-onset heart attack patients. They found that the delay before receiving hospital treatment differed significantly between the two groups. The average prehospital delay for slow-onset patients was 3.5 hours, compared to 2 hours for patients who experienced a fast-onset heart attack. After the onset of symptoms, 44 percent of fast-onset patients telephoned their general practitioner physician (GP), compared to only 28 percent of slow-onset patients. Similarly, 42 percent of fast-onset patients visited their GP, compared to only 24 percent of slow-onset patients. Patients with fast-onset heart attacks were also significantly more likely to call emergency medical services as their first medical contact. Fifty percent of fast-onset patients used an ambulance for transportation to a hospital, compared to 33 percent of slow onset patients.

Comparing the medical histories of patients with slow-onset versus fast-onset heart attacks reveals that patients with diabetes are significantly more likely to have slow-onset heart attacks, while fast-onset patients were more likely to have a cardiac history that included a stent or angioplasty. Diagnoses received by these patients also differed significantly. Forty-one percent of slow onset heart attack patients received diagnoses of unstable angina, compared with 24 percent of fast-onset patients.

The differences in behavior between these groups of patients suggest that there is a pressing public health need for education about non-Hollywood-style heart attacks and their symptoms. The delays in reaching a hospital and lower likelihood of contacting a GP for slow-onset patients means that they are not able to receive the full benefits of the lifesaving therapies, if any therapy at all is received.


O’Donnell S, McKee G, Mooney M, et al. Slow-onset and fast-onset symptom presentations in acute coronary syndrome (ACS): new perspectives on prehospital delay in patients with ACS. Journal of Emergency Medicine. (2013).


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