Acute myocarditis in diseases classified elsewhere

This code signifies an acute inflammation of the heart muscle that is a manifestation of another underlying disease process. It indicates that the myocarditis is not a primary condition but rather a secondary complication or symptom of a systemic illness.

Use this code when documentation clearly links acute myocarditis to an infectious, autoimmune, toxic, or other systemic disease. Examples include myocarditis secondary to influenza, diphtheria, or systemic lupus erythematosus. The medical record must specify both the acute myocarditis and the primary underlying condition.

• Always sequence the underlying systemic disease first, followed by this code for the acute myocarditis.
• Ensure documentation explicitly states "acute" myocarditis; chronic forms are coded differently.
• Do not use this code for idiopathic acute myocarditis; a different code exists for primary acute myocarditis.