Coronary artery disease (or CAD for short) is a disease in which there's decreased blood flow to your heart. This occurs over time in the form of Atherosclerosis, which is plaque buildup in the arteries of your heart that decrease the amount of blood flow that goes to your heart. The important thing to know is that this is the leading cause of death globally, affecting about 10 million to 150 million people annually, and about 20% of people over age 65 have this condition. It's also more common in men than women.