My guess is that it's probably dead above that sprout. Or the wood is damaged enough that it can't transport enough water and nutrients to leaf out the top.

Mine was extraordinarily late in leafing out this year (like within the last two weeks) and I'm in a warmer zone than you. This particular tree has also been known to lose it's first leaves to late hard freezes.Mine is not in the best location since it sits in a low point where mists and fogs gather and is prone to frosts. If yours is small enough to check the viability of some of the finer branches, do so to see if they're still green under the bark. I have had winter damage this year that I have NEVER seen before on my trees and there are one or two I am still playing a waiting game on before I assume they're goners.

Down the street there is a large Catalpa stump along the edge of the road. It was cut down years ago, but sprouts came up from the stump. The "sprouts" are now as big as small trees! I am amazed at the vigor of this craggy old stump. Should take a pic some time.

Yours may well do the same, but it does look kind of funny. You might consider transplanting a young tree next to your stump instead. Catalpas seed around a lot, as I am often pulling seedlings in the front garden from a tree that is across the street.

Its obviously alive, at least partially. Question is, how much is left. Wait til, say, July. Whatever hasn't leafed out by then, cut off. If *you* are OK with what remains, keep it. If not, replace it.

If the branches aren't dead then it should be fine

Those leaves don't quite look like Catalpa. Are you sure of the tree's id?