I am sorry, where did your cardiology training come from? I missed that. Myocarditis is a severe and life threatening illness.Not being able to pitch all year doesn't make it a life threatening illness for him. He will be fine, and statistically it's overwhelmingly likely that all the NFL players mentioned will be, too.
Beyond that, numerous young and healthy people are experiencing long term lung issues.
Here is what some actual heart experts have to say.
https://www.mayoclinic.org/diseases-conditions/myocarditis/symptoms-causes/syc-20352539#:~:text=Severe myocarditis can permanently damage,device or a heart transplant.
And I'll pull out the most important portion:
Severe myocarditis can permanently damage your heart muscle, possibly causing:
- Heart failure. Untreated, myocarditis can damage your heart's muscle so that it can't pump blood effectively. In severe cases, myocarditis-related heart failure may require a ventricular assist device or a heart transplant.
- Heart attack or stroke. If your heart's muscle is injured and can't pump blood, the blood that pools in your heart can form clots. If a clot blocks one of your heart's arteries, you can have a heart attack. If a blood clot in your heart travels to an artery leading to your brain before becoming lodged, you can have a stroke.
- Rapid or abnormal heart rhythms (arrhythmias). Damage to your heart muscle can cause arrhythmias.
- Sudden cardiac death. Certain serious arrhythmias can cause your heart to stop beating (sudden cardiac arrest). It's fatal if not treated immediately.