Coronary heart disease (CHD) is the result of blockages in the heart's blood vessels. Low blood flow to the heart due to blocked vessels can cause chest pain (angina). If the blockage lasts long enough, a section of heart muscle dies, a condition called myocardial infarction (a “heart attack”). Although many people with CHD have symptoms, including chest pain or shortness of breath, others have no symptoms at first and may not know that they have CHD until a heart attack occurs. Risk factors for CHD include older age, male sex, high blood pressure, diabetes, smoking, high levels of total or low-density lipoprotein (“bad”) cholesterol and low levels of high-density lipoprotein (“good”) cholesterol, and a family history of CHD. A patient's risk for heart attacks or angina can be estimated on the basis of risk factors. Treatments are available to reduce risk for CHD events in some patients at increased risk, such as those with high cholesterol or high blood pressure.