Is not your heart mang....heart problems have different symptoms. A sharp pain in the chest is usually something in the rib cage or some nerves. The heart, first of all, does not hurt. When you have a heart attack you have a pain accross the whole chest, not in one specific point but a pain like if a train passed over you; you get breathlessness, you feel like having five 45lb plates over your chest.
I get those sharp pains in the center of the chest sometimes after a brutal chest workout.