How is dx of myocarditis?

3 levels of dx, subclinical acute myocarditis (viral syndrome with no cardiac symptoms and one of elevated biomarkers, ECG finding of acute injury, reduced LV EF, abnormal imaging) Acute myocarditis (above criteria w/ cardiac symptoms (SoB/ chest pain) suggestive of pericarditis / myocarditis.) Definite dx when histo evidence of inflammation is seen doesn't need any labs/ images, so MRI considered useful