It's a sudden coronary artery dissection - when one of the arteries that supplies the heart suddenly tears. McDonald's had hers repaired then it appears that it ripped open again.
Coronary Artery Dissection: Not Just a Heart Attack
The aftereffects of a major cardiac event and ICU hospitalization can result in psychiatric disorders
Why a cardiac crisis also can be a mental health issue
What we are looking at here would be different than ICU delirium, which is a temporary condition that is multifactorial in origin. There is stress on the body, lack of sleep from clinical monitoring and procedures, multiple medications, lack of environmental time awareness (night/day), etc. This condition usually happens during the hospital stay and resolves relatively quickly.
OTOH, a thought disorder (psychosis) has a different sort of origin as we understand it. The physical and psychological trauma from the cardiac insult and ICU stay can certainly contribute, but there will be other psychosocial issues and likely a genetic susceptibility to mental illness. These illnesses are usually chronic and require more long-term management. The onset can be more insidious. It will be interesting to see what was going on with her during the last few months leading up to this event. Like if she just sort of "snapped" one day or if she had been acting odd for awhile.
So basically she could have developed a thought disorder anyway, but having the major medical issues contributed to her risk profile. Hopefully one day we will be able to understand it all better!