Women may worry more about breast cancer, but in reality, heart disease is the top killer of American women, claiming 300,000 lives a year, 7.5 times the number that die of breast cancer, according to the Centers for Disease Control and Prevention. Although heart disease is more often perceived as a men’s issue, since 1984 more women have died of heart disease than men.

Part of the reason may be that women’s heart attacks can differ from men’s and the American Heart Association (AHA) warns that women often fail to recognize the symptoms, ranging from torso aches and pains and nausea to anxiety, shortness of breath, dizziness and extreme fatigue. They may experience subtle symptoms for months and write them off as byproducts of menopause, heartburn or effects of aging. The National Institutes of Health states that 43 percent of women that have heart attacks experience no chest pain.

The difference between the more subtle signs of a heart attack in women and the more dramatic signs in men may help explain why 75 percent of men, prompted to act quickly, survive a first heart attack, while only 62 percent of women do, according to the AHA. “Research shows that women may not be diagnosed or treated as aggressively as men,” notes the Agency for Healthcare Research and Quality, part of the U.S. Department of Health & Human Services.