Heart disease is caused by narrowing of the coronary arteries that feed the heart. Like any muscle, the heart needs a constant supply of oxygen and nutrients, which are carried to it by the blood in the coronary arteries. When the coronary arteries become narrowed or clogged by cholesterol and fat deposits--a process called atherosclerosis--and cannot supply enough blood to the heart, the result is coronary heart disease (CHD). If not enough oxygen-carrying blood reaches the heart, you may experience chest pain called angina. If the blood supply to a portion of the heart is completely cut off by total blockage of a coronary artery, the result is a heart attack. This is usually due to a sudden closure from a blood clot forming on top of a previous narrowing.

Cholesterol is a waxy, fat-like substance that occurs naturally in all parts of the body and that your body needs to function normally. It is present in cell walls or membranes everywhere in the body, including the brain, nerves, muscle, skin, liver, intestines, and heart. Your body uses cholesterol to produce many hormones, vitamin D, and the bile acids that help to digest fat. It takes only a small amount of cholesterol in the blood to meet these needs. If you have too much cholesterol in your bloodstream, the excess is deposited in arteries, including the coronary arteries, where it contributes to the narrowing and blockages that cause the signs and symptoms of heart disease.

Risk Factors and Heart Disease
Risk factors are conditions that increase your risk for developing heart disease. Some risk factors can be changed and others cannot. In general, the more risk factors you have, the greater your chance of developing heart disease. Fortunately, there are things you can do to address most of the risk factors for heart disease. The risk factors that you cannot control include:

• Age (45 years or older for men; 55 years or older for women)
• Family history of early heart disease (father or brother affected before age 55; mother or sister affected before age 65)
  
  The known risk factors for heart disease that you can do something about include:
• High blood cholesterol high total cholesterol and high LDL ("bad") cholesterol
• low HDL ("good") cholesterol
• Smoking
• High blood pressure
• Diabetes -- if you have diabetes, your risk for developing heart disease is high, as high as a heart disease patient's risk for having a heart attack. You will need to lower your cholesterol under medical supervision, in much the same way as a heart disease patient, in order to reduce your high risk of getting heart disease.
• Obesity/Overweight
• Physical inactivity