I have had 5 cases of malignant catatonia which is probably more than most psychiatrists will see in their lifetime but doing neuropsych at an academic center for some yrs you get an enriched population. It cannot usually be treated with meds (I've tried everything including IV benzos, IV valproic acid, zolpidem, IV barbiturates, memantine, amantadine, abilify, clozapine etc). 4/5 of those patients died even with ECT. Unfortunately, it is very hard to get ECT quickly on incapacitated pts where I am so there was a delay in getting treatment and we will never know if those patients would have survived otherwise. One of the patients went into cardiac arrest while getting ECT.
The condition is almost certainly under diagnosed as well. I used to teach the neurologists and hospital medicine docs on catatonia so they were much better at picking up cases of catatonia than most places.