I think not raising the flop is a mistake, particularly if you have the A [img]/images/graemlins/heart.gif[/img]. This raise is for value. It may even protect you hand if the SB reraises.

edit: oh wait, there's a bet and a raise. Er, I'd still 3-bet it. SB could have a draw and the raiser may only have top pair. Pump it, especially if you have the ace of hearts.