Not necessarily. The curse behaves differently across the books. One example is how it threw Dumbledore through the air, where other times it simply drops people. JKR plays with its precise action to maximise dramatic effect.

The fact that the curse was immediately lethal with no other visible damage says to me that it was the Killing Curse, which is the only spell we know of that does that. It could be another curse, but we have no real reason to think so. Especially as the existence of such a curse would be rather redundant.

 

Given that it hit her in the heart or "right above the heart", it could be any curse that does sufficient physical damage, really.

 

I didn't even know this became a thread.