Fulminant and acute lymphocytic myocarditis: the prognostic value of clinicopathological classification.

Myocarditis, characterized by myocardial inflammation, may lead to left ventricular dysfunction, heart failure, arrhythmias, conduction system disorders, and sudden death. While lymphocytic infiltration is most common, both eosinophilic and giant cell myocarditis are recognized entities. Lymphocytic myocarditis may result from systemic endocrinological, rheumatological, or toxic disorders; but is more commonly a manifestation of viral infection, either primarily or secondary to an immune response. In the past 15 years, while substantial effort has been expended developing and applying a precise histological classification scheme, only a few investigators have addressed the variable clinicopathological syndromes with which patients may present. In 1991, our group proposed a clinicopathological scheme of lymphocytic myocarditis based on the similarities between myocarditis and the four syndromes with which viral hepatitis manifests: fulminant, acute, chronic–active, and chronic–persistent. Patients with fulminant myocarditis had a very distinct and more favourable natural history than those with acute myocarditis (this group comprising the majority of patients with myocarditis). Patients with fulminant myocarditis (approximately 10% of the total) had a distinct onset of symptoms of short duration prior to presentation with severe congestive heart failure. These patients could date their symptoms to within a 2-day period and often had fever. By contrast, the presentation of acute myocarditis resembled that of adult patients with congestive heart failure, with gradual yet progressive development of fatigue, exercise limitation, and dyspnoea. The only way patients with acute myocarditis could be separated from other forms of cardiomyopathy and heart failure was by endomyocardial biopsy demonstrating lymphocytes with or without myocyte necrosis. The most clinically relevant observation was that fulminant myocarditis patients, although much more ill at presentation had an improved chance of full recovery and long-term survival. At the initial presentation, however, these patients required aggressive haemo-