When blood flow to the heart is restricted, chest pain, or angina, can result. If blood flow is nearly or completely blocked, a heart attack can occur, killing muscle cells in the heart. Angina usually disappears with rest or medicine, such as nitroglycerin. A heart attack requires much more intensive therapy in a hospital. If the pain is severe or doesn't go away, or if the symptoms are those of a heart attack, call 911 and get evaluated at a nearby hospital emergency room.