Did you really mean 1 ace and not 1 keycard? Anyway, it seems like our chances are
- Try to lead ♥ and expect to defeat by taking 2 red tricks.
- Try to cash ♦ A and expect to defeat when pd has Qxx ♠
In both cases you need pd to hold a Q, so they are playing a slam with 28 hcp. This tells me that responder has shape for driving to slam with less than slam values. At least 5-5.
In order to
♥ lead to work, you need them to play a 5-3 fit otherwise they will be able to clear trumps and run clubs pitching
♥ losers OR all the diamonds NT opener holds. Of course there are exceptions to this but still. You also need the shapely hand not to be short in
♥ suit (5125 wont' help you even if you find Q with your pd)
But
♦ A lead will work each time pd has Qxx or Kxx
♠ in addition to when they hold a hidden 5-2
♦ (responder 6142/5125 snd opener 3253/3352) so pd can ruff 2nd
♦. Unlikely but possibility. Also another tiny chance that we can cash AK
♦
This is why I asked the question whether 4 NT was asking only aces or keycards. In keycard system, responder could have asked about the trump Q, or maybe he did not bother?