[staunchdog]

After Villian pushed all in:
There's 1450 in the pot.

It'll cost you 1000 to call.

If he has one heart and a pair, there are six hearts that won't pair the board, so 40/46 river cards favor you (.87 chance of winning 1450 dollars, .13 chance of losing 1000). Your EV is $1132

If he has two hearts, you have 10/46 outs (.22 chance of winning 1450, .78 chance of losing 1000). Your EV is -$561

Let p be the chance that he has a heart and a pair (so 1-p is the chance he has a made flush).

This math works out very nicely. You should call if he has the pair and the draw, instead of the flush, at least 1 time in three:

$1132*p >= 561*(1-p)
p >= .33