Board Thread:General Discussion/@comment-10197675-20130806142227/@comment-1470368-20190420024941

There really isn't any "mystery" to them anymore. It's already been presented to us right in TES3: Morrowind that Kagrenac's attempted tuning of the Heart of Lorkhan disintegrated (evidenced by Ash Piles) pretty much the entire Dwemer race, only sparing Yagrum Bagarn because he was in an entirely separate realm at the time.

Regardless of Kagrenac's plan to create a new "god", it backfired. It's likely he died as well, and possibly before the rest of his kind, considering the manipulations of the very individual who ends up "guarding" the Heart of Lorkhan (Dagoth Ur).

And it wouldn't have mattered if he wore Wraithguard while attempting to draw power from the Heart of Lorkhan, due to the psychic link he had with the rest of the Dwemer.