Well, you want that last $550, and you want it in the pot now. I think he has AQ or AA but it's not impossible that he has 2 hearts or even air.

If he has air... I doubt you get any more into the pot unless you call and river non-heart connects him (say he has 99 and river is 9)...well that's not exactly air, but 3rd pair on a AQXX board... pretty air like.

If think if you re-raise less than all-in and he's decent he is probably going to fold only worse hands. If you push, he might think you are bluffing and call with a worse hand. In anycase - you are probably golden unless he has AA ("that's poker").

Pings' point about maskarova is good too.