LONG SURVIVAL WITH GIANT-CELL MYOCARDITIS

Several aspects of giant cell myocarditis remain controversial, includ ing the natural history of the disease and the nature of the giant cel ls. We have observed three patients who had long survival with chronic active giant cell myocarditis. The first patient was a 59-yr-old fema le who had a 10-yr history of complete heart block which was found at autopsy to have been caused by giant cell myocarditis. The second pati ent is a 36-yr-old female who received a heart transplant 5 yr after a biopsy proven episode of active myocarditis, and examination of the e xplanted heart revealed giant cell myocarditis. The third patient was a 41-yr-old male who received a heart transplant 2 yr after developing progressive heart failure, and the explanted heart had giant cell myo carditis. On immunohistochemical study of the three hearts, the giant cells stained with the macrophage markers lysozyme and KP-1 (CD-68). S taining of the same cells with desmin and actin was focally positive i n a punctate pattern, correlating with the ultrastructural presence of myofibrils within giant cell phagolysosomes. The associated lymphocyt ic infiltrate stained primarily for the T-cell markers CD-3, CD-45RO, and CD-43 whereas only a few of the lymphocytes stained with the B-cel l marker CD-20. The long histories of cardiac dysfunction in the three patients show that giant cell myocarditis may have a protracted cours e. The morphologic studies show that the giant cells are of histiocyti c origin but can contain phagocytosed components of myocytes, observat ions that may account for the controversy surrounding the nature of th e giant cells in giant cell myocarditis.