It might start with chest pain, but the symptoms are often more subtle. Maybe your back hurts for no reason or you need to sit down after a bout of nausea or shortness of breath. In the U.S., heart disease claims more victims than any other cause of death, accounting for 25 percent of deaths in women each year. Women need to be especially careful because they are less likely than men to experience the signature crushing chest pain, making them less likely to rush to the hospital after the onset of symptoms. By the time most women reach the emergency room, the damage is severe. Two-thirds of women fail to make a full recovery after a heart attack, making heart disease the leading cause of disability in women.

What happens? In heart disease, your arteries become harder and narrower as plaque builds up, making it difficult for oxygen-rich blood to reach your heart. Up until the seventh decade of life, men are more likely to get coronary artery disease. This form of heart disease is caused by plaque buildup in the large arteries that carry blood from the lungs to the heart, which can cause heart attacks when blood clots break loose and block blood flow to the heart, or plaques rupture and clots form at the rupture, blocking flow. Women are more likely to get small vessel disease, which affects the small arteries within the heart that keep it healthy.

Why women? In some ways, women are better off; on average, heart disease affects women 10 years later than it affects men. Estrogen protects against heart disease by raising your levels of good cholesterol while lowering bad cholesterol (though this protective benefit wanes somewhat after menopause, when your estrogen levels drop). And yet women, being more susceptible to small vessel disease, are more likely to die from heart disease than men. The symptoms are less noticeable than they are in traditional heart disease, and small vessel disease is harder to recognize in the doctor’s office. As a result, women aren’t as likely to notice that there’s a problem until their heart has suffered major damage.

Take charge. Reduce your risk of heart disease by leading a healthy lifestyle. Obesity, high blood pressure and high cholesterol all contribute to heart disease. Some risk factors—smoking, stress, depression, obesity and low estrogen levels—affect women far more than men. To avoid this silent killer, eat a healthy diet, exercise at least 30 minutes most days of the week and stop smoking and avoid secondhand smoke.