Myocarditis is most commonly caused by which of the following?

• A. Atherosclerotic disease
• B. Bacterial, fungal, or viral infections
• C. Hypertension
• D. Autoimmune disease exclusively

Answer: (B)

Infections, especially viral infections, are the most common cause of myocarditis. The heart muscle becomes inflamed after a viral illness—common culprits include Coxsackie B, adenovirus, parvovirus B19, and others. Bacterial and fungal infections can cause myocarditis but far less often. Autoimmune processes can contribute, but they are not the exclusive or most frequent cause. Atherosclerotic disease and hypertension affect the coronary arteries or cause remodeling, not the typical inflammatory process of myocarditis. So infectious etiologies, particularly viral, best explain the usual cause.