Younger women hospitalized with heart attacks are more likely to die than men of the same age, "provocative" U.S. research showed.

The findings, published Tuesday in the Journal of the American Medical Association, indicate that women are more susceptible to "silent" heart attacks, which do not feature chest pain -- enhancing the risk, as that is one of the warning signs that drives sufferers to seek medical help.

Related: Why women may not know they are having a heart attack

The study involved 1.4 million patients who experienced a heart attack between 1994 and 2006. It found that 42 percent of women arrived at the hospital without chest pain, compared to 30.7 percent of men.

Of those hospitalized, 14.6 percent of women died, compared to 10.3 percent of men. The differences between the sexes were more pronounced in patients aged under 55 and faded away by the age of 75.

Scientists could not fully explain the gender disparity, according to the study's lead author, Dr. John G. Canto, director of cardiovascular prevention research and education at the Watson Clinic in Lakeland, Fla. However, he believes the hormonal difference is one of two key factors.

"The second factor is that if we're telling patients the classical symptom of heart attack [is] chest pain, and they lack it, then we should not be surprised that younger women with atypical symptoms delay getting to the hospital," he said. "And once they do present, the doctors may be unaware these women are having heart attack because they are young and have different presentations."

Canto described atypical symptoms as shortness of breath and discomfort in areas other than the chest.

"Our results are provocative," he said. "If confirmed by different studies and databases, we need to tailor the one-size-fits-all message to also include a message that younger women may have different symptoms and their risk for dying is increased."