Chronic pernicious myocarditis.

Abstract Attention is drawn to a type of chronic myocarditis characterized by a protracted, and yet relentless, downhill course, sometimes with remissions and exacerbations, culminating often in unexpected death. Congestive myocardial failure is very common. Because of the relentless downhill course, the term “pernicious myocarditis” seems appropriate. This type of myocarditis is in no way a specific anatomic entity, and any chronic myocarditis occasionally may cause a protracted and relentless downhill course. However, from our study of the pertinent literature, and from our own observations, it appears that in our geographic region a chronic form of isolated myocarditis is the most common cause. The etiology of chronic pernicious myocarditis is obscure, just as is that of acute isolated myocarditis (Fiedler's). The resemblance of pernicious myocarditis to chronic Chagas' myocarditis, both clinically and anatomically, is stressed. However, using all of the up-to-date methods of histologic examination at our disposal, we never encountered leishmanias—so common in Chagas' myocarditis—or structures resembling parasites. Of 225 cases of myocarditis, 6 were reclassified as chronic pernicious myocarditis. The clinical abstracts and autopsy findings of these patients are presented, and the protracted, relentless downhill course with progressive myocardial failure is stressed. Two patients were misdiagnosed as having stenosis of the mitral orifice, and one as having pericarditis. The electrocardiographic alterations are noted. At autopsy all cases showed a large heart, with no changes in the endocardium or pericardium. On microscopic examination there was a true chronic, mainly interstitial, myocarditis, with young connective tissue compressing and eventually replacing heart muscle fibers, and an interstitial infiltration of inflammatory cells. The importance of recognizing pernicious myocarditis lies principally in its grave prognosis. After a seeming recovery from a slowly developing illness which may or may not be recognized as myocarditis, the patient shows signs and symptoms of early myocardial failure. Once this happens, it is bound to recur. These are the patients who either become cardiac invalids or recover, only to develop repeated attacks of myocardial decompensation and to succumb to one of these. This realization is implied in the term “pernicious” myocarditis.