Conventional wisdom has it that heart attacks come out of the blue. We're also trained to expect a heart attack to happen a certain way; the victim clutches his chest, writhes in pain, and collapses. But for women, it often doesn't happen that way. Study after study shows heart attacks and heart disease are under-diagnosed in women, with the explanation being that they didn't have symptoms.

But research shows that's not the case. Women who've had heart attacks realize, looking back, that they experienced significant symptoms -- they just didn't recognize them as such.

In a study funded by the National Institutes of Health and published in Circulation: Journal of the American Heart Association, 95 percent of women (that's almost all!) who'd had heart attacks reported experiencing symptoms that were decidedly new or different from their previous experience a month or more before their attacks.

Even when a heart attack is occurring, women are often slow to realize what's happening and call a doctor. The reason? Women's heart attack symptoms are different than men's. This failure to recognize heart attack signs in women has led to a grim statistic: women are more likely to die from sudden cardiac death than men are, and two thirds of women who have a heart attack don't recover completely.

To prevent a heart attack from sneaking up on you, watch for these 7 little-known signs of heart attack