Myocarditis and dilated cardiomyopathy: twins or distant relatives?

Myocarditis and dilated cardiomyopathy both commonly present as new unexplained heart failure. This similarity raises the question of the interrelation of these disorders. What proportion of dilated cardiomyopathy begins as myocarditis, what other cardiac insults commonly lead to myocarditis and how often endomyocardial biopsy yields the diagnosis of myocarditis when present, are unknown. Proof that immunosuppressive treatment of myocarditis is beneficial is also lacking.