I searched duckduckgo for "myocarditis" and the first link that came up was the following:
https://www.mayoclinic.org/diseases-conditions/myocarditis/symptoms-causes/syc-20352539
About complications they claim: Usually, myocarditis goes away without permanent complications.
Yet before 2020 that sentence was not there, it just read: "Severe myocarditis can permanently damage your heart muscle, possibly causing: [...]"
I wonder why they felt like they had to change that, what do you think?
He is correct that you don't get just a little myocarditis, it is always a severe problem, but it is not always permanent or a death sentence.
I had a heart attack caused by myocarditis 11 years ago, so I have some personal experience. I am not a doctor, so take what I say accordingly.
Myocarditis is inflammation of the heart muscle. Inflammation can go away with treatment and/or lifestyle changes, but it doesn't always go away. Many people live most of their lives with widespread inflammation throughout their bodies, and it causes a huge number of other secondary health problems.
Back to my heart attack and where my words are coming from: My heart attack seemed mild initially, but it almost killed me (I had one of the near death experiences you hear about all the time; my wife's voice begging me not to go is what called me back). The cardiologist on call when I was brought into the cardiac unit had been the chief of cardiology at that hospital for 30 years, so he knew his shit. He was my attending doctor throughout my hospital stay. He told me that my blood work (every 6 hours for the entire hospital stay) indicated heart muscle damage initially that stopped happening after a few hours, but in spite of using every single form of imaging that was available at the time, they couldn't find where the damage actually occurred (maybe they could have with today's technology). He said I was extremely lucky.
Bottom line, my myocarditis did go away, although I'm always at risk of having it triggered again. It has not been an ongoing problem thus far, and 11 years later I am still here and still going strong. My heart did suffer some minor damage based on blood testing, but functionally heart tests in recent years show that my heart is relatively healthy for someone of my age and fitness level.
My takeaway? Myocarditis is a very dangerous and life threatening event, but like most other things it can be acute (short term) or chronic (long term). It can go away, but it doesn't always. Obviously it's a million times better to not get it at all than to have it go away after the fact, but having it is not always a death sentence or guarantee of a shortened lifespan. On the other hand, it can kill you quickly before you even know you have it, as it nearly did to me. But IF you are lucky enough to survive initially and are diagnosed, treated properly, and make some lifestyle changes if needed, it is definitely possible to recover and have the myocarditis go away and still live a long life.