What is the most important cause of heart disease?

Although there are several different causes of heart disease, most are due to a buildup of plaque in the blood vessels (arteries) that feed the heart. Whenever the blood flow feeding an area of the heart is interrupted, that area of the heart dies. This is what we call a heart attack. Fortunately, the kinds of things that contribute to heart disease are mainly lifestyle related and very preventable, so this is an area where you can make a big difference.