Here we are in 4H with a ten-card fit. Better not go down.
Lead: King of Spades.
A problem only arises if someone has three hearts. That does at least mean that person can be put on lead at a convenient moment. The diamond suit has that 3-3 aspect which means the finesse can sometimes be given up for an endplay. So win the Ace, start with the King of trumps, finding East has three, then play a heart to the ace, ruff a spade, and play three rounds of diamonds from the top. You give up the finesse, but if it was winning, East is on lead and can cash his trump, but must then play a club. If the third round of diamonds loses to West, he can play a club, but you put in the King. If East wins, he is endplayed, if he ducks, you concede the trump and East is endplayed.