a very important 1/2 hand from Vegas last week - did I blow this?.

[B1GF1SHY]

If you were afraid of the heart then you should've check/called the river, this also might induce a bluff from him which you can pick off, plus it won't make the pot huge on the river.

You mentioned that he was chatty in the AK hand when he was quite confident he had the best hand (which he didn't). In this hand he's very quiet, perhaps he's gone silent and trying not to give anything away since he could be bluffing?

Tough spot, I call.