The lead looks like either top of Nothing or Mud (also promising nothing) so playing back another Heart will be fruitless.

But what to play next ? As you are not sure what the best thing to do is, you should  cash your other Ace and see if partner encourages or discourages. Partner will discourage the Diamond switch so all you are left with now is to play  a low club showing an Honour (your King). Partner is only too pleased to win and play back a Club to immediately beat the contract by one. With any other defence declarer will get a chance to chuck a Club loser away on third round of Hearts

You can also view  watch the following movie to see how the hand pans out. (You need bridgvu.exe programme  or BridgeBase programme on your machine already to view it ) and it is available free from

http://www.haroldschogger.com/videos.htm