Most likely... You die. Getting shot in the chest is a very devastating MOI (mechanism of injury). Three main issues can arise as a result of just one well placed GSW; If the projectile hits the heart othpericardium fatal bleeding into the sack or complete destruction of thud organ can result in death really quickly. Aditionally there are several major blood vessels exist in the chest, including the aorta, which if perforated can cause axanguanation (bleeding out within minutes). If one is lucky the the bullet would hit the lung, which is not an instant death sentence, however that's where luck will end, as a puncture of the plural space surrounding the lungs would become compromised, allowing are into the cavity reducing oxygen intake gradually; called a tension pneumothorax.
