Study co-author Dr. George Sopko of the National Heart, Lung, and Blood Institute of the National Institutes of Health and colleagues examined 35 years of research that yielded 69 studies and found that -- depending on the size of the study -- between 30 percent and 37 percent of women did not have chest discomfort during a heart attack. In contrast, 17 percent to 27 percent of men did not experience chest discomfort.

The study, published in the Archives of Internal Medicine, also found that older people are more likely to have heart attack without chest discomfort.

The researchers pointed out that women are, on average, nearly a decade older than men at the time of their initial heart attack and more research is needed to determine the degree to which gender independently influences heart attack symptoms.

The researchers concluded that current research does not indicate a need to differentiate heart attack symptoms in women from those in men, and public health messages should continue to emphasize chest pain or discomfort, shortness of breath, and other common signs of heart attack.