We have nine top winners, and counting from South's hand four potential losers. We can eliminate a heart loser by ruffing one with dummy's short trumps. We would need three trumps to draw them, so will need to ruff a heart before that. It would be better if we can ruff high just in case East has a doubleton. We can find out if that is safe by taking a trump in hand first. When both defenders follow, we know there are only three remaining. So, we can cash ♥K and ♥A, and then ruff our third heart high. Then we draw remaining trumps.
Ruffing a loser with short (or equal) trumps gains a trick.
