A heart attack occurs when the heart muscle is deprived of oxygen. This causes cells of the heart tissue to die.
Coronary arteries supply blood and oxygen to the heart.
When these arteries do not deliver enough oxygen to the heart muscle, pain results. This pain is known as angina. It is a sign that the heart is not getting adequate blood and oxygen. If the heart muscle is deprived of oxygen for a long enough period of time, the heart cells begin to die. This results in a heart attack.