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).
Coronary artery disease is a major cause of heart attacks. Heart attacks can also be caused by blood clots that form as a result of the use of certain prescription drugs (Vioxx, Bextra, Celebrex and Zelnorm) that thicken the blood, making it stickier and more likely to clot.