Hello Bunny,
I, too, am at the 'Early Diagnosis' stage.
I was diagnosed nearly 6 months ago & though I have family most of them live abroad so like you,
I live alone.
I totally understand your quandary re medical intervention to prolong life & am sure many of us have, are, or will, face similar issues but no-one can or will advise you what to do when faced with such decisions as we are all individuals & last I heard there are literally hundreds of forms/types of Dementia and so our experience & likewise, our response to it, is as different & varied as we are.
I can't advise/answer about your Heart options as that has to be your decision
but what I can tell you about is how I'm personally dealing with my own Memory Loss diagnosis...
After receiving the diagnosis in the form of a letter from the Consultant I had seen, there was also a referral for a scan which I declined as I'm Claustrophobic & prone to Anxiety Attacks,
plus I know myself well enough to I know that if I was given irrefutable proof I would decline rapidly.
Instead, I decided I would tell everyone I'd already told about my diagnosis when I was in shock, that now it's far more likely to be 'Fibrofog' as I've had Fibromyalgia for 13 years, so am no stranger to being befuddled & scatter-brained, which is absolutely true.
Then, having made contact with a Dementia Researcher who was kind enough to update me on the latest research, I started to empower & reclaim myself by putting into practice all the things I could do to enable me to live my best life, which crucially included increasing blood/oxygen flow by excercising, especially Aerobics, Resistance Training ie exercising whilst lifting/carrying weights (I started with a couple of tins of Baked Beans but have now got myself some small 2kg weights) which you can even do whilst sat watching TV & also, very crucially walking especially Speed Walking but am working on that, as I'm slowly upgrading from my usual languid stroll.
Plus, believe it or not, singing whilst doing any of these activities has shown great results in increasing blood flow/oxygen levels.
Basically, anything that increases Blood/Oxygen flow is great according to the latest research
but don't take my word for it, Google it & do the research for yourself.
Maybe you could also considering putting yourself forward to join in a research project
or Volunteering at an Alzheimers/Dementia shop/location/group
&/or join groups in your locality so you can interact with others who are in the same boat
but try to avoid calling it The Titanic. even if it does sometimes feel like we're on it.
What I'm saying is, as far as our short term memory issues etc go, the meds are good, are getting better all the time & will help.
Nevertheless, no problem is as important as your attitude to that problem is
ie Self help by being active & proactive in finding what will help you to live your best life is a positive option for you, as well as for everyone who is facing similar challenges.
Anyway, with the state of the world & what's happening in it right now,
none of us know if we'll be here next week or even tomorrow - so make the best of it
because that's all you can do, is to make the best of the time that has been given to you.
Yes, it might end badly & the Pessimist may be proved right in the end
but the Optimist has the better journey.
Onwards & upwards! Oh, and have a hug x