That would be (most likely) an absolute world record in surviving with a heart transplant. In 2016, someone died with a survival Guinness Record of 33 years [1], your Aunt would exceed that quite far. Current (non-official) US record supposedly is 35 years [2]. I am not saying your are mistaken, just noting that she might be an outlier.

[1] https://www.bbc.com/news/uk-england-beds-bucks-herts-3554369... [2] https://www.wbay.com/2021/06/29/green-bay-man-nations-longes...

There are multiple types of dementia, a woman with known heart disease might have vascular dementia (dementia related to decreased blood flow to the brain). This article is really about alzheimers (although that's not clear from the title, it should probably say "(maybe) don't get alzheimers").

Does she take calcineurin inhibitors?

Wow - that is an absolutely incredible result for a heart transplant! Very unusual situation. Be interesting to understand the specifics - and the team doing this kind of work!