I don’t know anything about North Korea but I’m guessing this could lead to some sort of succession/legitimation crisis:
NEW: Trump admin received information that Kim Jong Un had heart surgery last week and if he's alive, his health is poor, I'm told. KJU hasn't been seen at key events in recent days. It's unclear to US officials if he's dead or alive. (CNN 1st reported his condition's grave.)— Jennifer Jacobs (@JenniferJJacobs) April 21, 2020
Katy Tur deleted a tweet reporting that Kim was brain dead.