Can acute viral myocarditis be a congenital condition in children?

Yes: Congenital by definition means existing at (and sometimes before )birth. A congenital myocarditis is one complication of measles or rubella in a newborn & may occur with an unvaccinated mother infected in the later stage of pregnancy. Other maternal viral infections may also trigger a myocarditis in a newborn. If the infection occurs after birth, it would not be considered acongenital condition.

Not really: Myocarditis is an inflamatory (acquired)condition of the heart muscle. It may be coused by viruses or other infections. Occassionally it is caused by inflamation without infection. Rarely babies acquire myocarditis during gestation and are very sick at birth. It is not truly congenital.