This is all new to me myself but from what I've been able to glean, myocarditis can vary in its severity to quite some degree. If it is mild, you might have good prospects of complete recovery. But if it's occurring to the extent that you need to be hospitalised, that's where you're dealing with a likelihood of heart scarring and permanent damage, and you have to entertain the possibility some of the grimmer prognoses like heart surgery or severely shortened life expectancy.