Heart attack symptoms in women differ from that of men, claims study.
Overall men have significantly more heart attacks, but under the age of 55 women are more likely to die from one.
According to a study of more than one million people in the US, without displaying the classic chest pain symptoms of a heart attack, some women may not be getting the right kind of treatment.
The research found that among younger women, those aged under 55, the differences in symptoms with men of the same age were striking.
Overall, 42 percent of women did not experience chest pain compared with 30 percent of men.
Once admitted, the study found that women were more likely to die than men from the same age group.
The study adds to evidence that women can experience quite different symptoms to men.
"Optimal recognition and timely management of myocardial infarction (MI), especially for reducing patient delay in seeking acute medical care, is critical," the BBC quoted the authors of the study as saying.
"The presence of chest pain/discomfort is the hallmark symptom of MI.
"Patients without chest pain/discomfort tend to present later, are treated less aggressively, and have almost twice the short-term mortality compared with those presenting with more typical symptoms of MI," they said.
In fact the average age of women admitted to hospital in the study was 74, compared with 67 for men.
Cathy Ross, senior cardiac nurse at the British Heart Foundation, said a heart attack did not necessarily mean dramatic and excruciating chest pains.
"Symptoms vary; for some the pain is severe and yet others may feel nothing more than a mild discomfort or heaviness. The most important thing to remember is if you think you're having a heart attack, call 999," Ross said.
"Younger women may need to heed that advice more than most because they appear to be less likely to have chest pains.
"Their symptoms can be overlooked by inexperienced medical staff because heart attacks in young women are rare.
"More research will hopefully identify why there are such variations in the way heart disease affects men and women," she added.
The study has been published in the Journal of the American Medical Association.