What is the events occurring in the heart during a heart attack?

During a heart attack your heart muscle is starved for oxygen, therefore it goes into spasm, that's why your chest hurts and your pulse rises. Also, your heart is not pumping efficiently, because it's going too fast, and the blood is not oxigenated properly in the lungs (that's what causes patients to hyperventilate), so you can faint or become unconcious because not enough blood is reaching your brain.
Heart attack risk goes up in men over 45 and women over 55 but heart attacks can happen at any age.