You don't say what the pot size was, on the flop, or how many active players there were. How much was your bet? How much was the all-in?
With effective stacks of 33xbb, this is probably something I don't get away from heads-up, if there has been a raise pre-flop and I have any history with the player that suggests he could be pushing with only a single big heart. My step-brother is an example of a player that I would be obligated to call against, in this spot. He would push any big heart, much of the time, and the Ace of hearts pretty much 100% of the time just because he knows I am unlikely to have a hand strong enough to call, and he can still win even when I do call. That's a very specific spot against an aggressive player.
With the pot multiway and limped, I might just have to let it go. It's too easy for someone to have a flush. More importantly, it is unlikely anyone is willing to play a big pot, multi-way, with less than a flush. These are all signs of passive players trying to flop the nuts before putting in a lot of money.
