Pre-Algebra on Khan Academy: No way, this isn't your run of the mill arithmetic. This is Pre-algebra. You're about to play with the professionals. Think of pre-algebra as a runway.
Coronary artery disease. The most common underlying cause of heart attack is atherosclerosis, a condition in which a fatty substance called plaque builds up on the inside walls of blood vessels. When this occurs in the coronary arteries, it's known as coronary artery disease (CAD).
There are a few cardiac conditions that can cause heart attacks. One of the most common causes is plaque buildup in the arteries (atherosclerosis) that prevents blood from getting to the heart muscle. Heart attacks can also be caused by blood clots or a torn blood vessel. Less commonly, a heart attack is caused by a blood vessel spasm.