One of the easiest most convenient spots on the body to inject. No, it's not a "necessary spot or anything like that, but if you've injected for a long time and if you're injecting a lot, say on a contest diet where you may be injecting short esters daily, you need all the spots you can get.
...and like everyone's said, there is absolutely no way you could even get close to your heart...not unless you have a 8" pin and it's strong enough to penetrate your breast plate.