As someone who had heart surgery at 28 and lives with an artificial valve, now 13 years old
I didn't get an exact answer from the doctor about why the valve was damaged. A combination of several factors or bad luck. But what's there has to change.
Since you don't want to leave the city, and I think the city is a great catalyst for stress and other problems.
The more time spent in nature, from personal experience, the garden helped me recover and got me back on my feet quickly.
Maximum elimination of fast food, I know it's easier to buy than to prepare, but all that comes at a cost.
Maximum avoidance of stress, and for many things that are "important" to us, they actually don't matter.
You should be moderate in everything.
Although I personally haven't completely separated myself from the city, I drive to work every day, I think that I should stop doing that...