started before she had any suspicion about what could be the problem
That is so common. As someone who has regular panic attacks, it takes months to admit that there is something wrong with you, that it’s not a form of covid, no you’re not dying, you can breathe even without concentrating, your appendix had already been cut out, and the only thing you need is a psychiatrist. Being smart and able to analyze some random numbers and events only adds to the problem, because you sound reasonable for much longer time. For your entire life you believe that you are a perfect error-free mechanism that cannot be wrong. Of course it takes time to realize that it’s not true (and never was, really).
It’s very hard to realize that an issue may be completely inside your very smart and logical mind. It must be something in the air, or germs/viruses, or vibrations. I bet that at least one of the doctors suggested her to check her mental health, but we always dismiss that, because we are fine, alright. We are not the type of person who could need that, gosh, that’s laughable. Only idiots and schizophrenics may have mental health issues, not us. Of course this little nuance couldn’t make it into the article.
E.g. in my case it took nine months of occasionally “dying”, a bunch of pricey and unpleasant procedures, then two more weeks of the chronic state and three doctors suggesting it, before I decided to go check my mind. Symptoms rate dropped 50% after the first appointment and 45% more after I completed my first “homework”.
High heart rate: https://www.medicalnewstoday.com/articles/175241#causes (anxiety)
Low heart rate: https://health.clevelandclinic.org/is-a-slow-heart-rate-good... (nothing psychological)
You would need to know a lot more before you worry about 50 being low.
And yes, I had to get an EKG and the doctor raised his eye brow at my heart rate, but I said I run and he immediately Moved on.