[Antimyosin scintigraphy for diagnosis and follow-up of patients with clinically suspected myocarditis]. / Antimyosin-Szintigraphie zur Diagnostik und Verlaufskontrolle bei Patienten mit klinischem Verdacht auf Myokarditis.

Antimyosin-scintigraphy is believed to have a high specificity but a low sensitivity for the diagnosis of myocarditis when histological analysis of endomyocardial biopsy is used as the reference method. However, the histological evaluation itself seems to have a low sensitivity for the diagnosis of myocarditis. Therefore, immunohistological techniques have been developed for the detection of lymphocytic infiltrates and increased expression of HLA antigens in the myocardium. The present study compares the results of antimyosin-scintigraphy with histological and immunohistological analysis of the endomyocardial biopsy. 65 patients with clinically suspected myocarditis underwent antimyosin-scintigraphy and histological and immunohistological analysis of the endomyocardial biopsy. Myocarditis could be diagnosed histologically in only 9/36 (25%) patients with a positive antimyosin scan but additional immunohistological analysis revealed lymphocytic infiltrates in 31 (86%) of these patients. In 29 patients with a normal antimyosin scan, histological analysis showed evidence of myocarditis in 3 (10%) patients; additional immunohistological evaluation disclosed lymphocytic infiltrates in 17 (59%) patients. With immunohistological analysis of the endomyocardial biopsy as the reference method, antimyosin-scintigraphy has a high sensitivity but a lower specificity for the diagnosis of myocarditis. Detection of autoantibodies against human cardiac myosin in patients with myocarditis is associated with a significantly lower incidence of positive antimyosin scans in these patients. Antimyosin-scintigraphy was repeated after six months in 14 patients with myocarditis. Histological and immunohistological evaluation of the endomyocardial biopsy now showed persistent myocarditis in 3/8 patients with a positive antimyosin scan and in 5/6 patients with a normal antimyosin scan.

Antimyosin scintigraphy and immunohistologic analysis of endomyocardial biopsy in patients with clinically suspected myocarditis--evidence of myocardial cell damage and inflammation in the absence of histologic signs of myocarditis.

OBJECTIVES: This study compares the results of antimyosin scintigraphy in patients with clinically suspected myocarditis with histologic and immunohistologic findings in the endomyocardial biopsy. BACKGROUND: In patients with clinically suspected myocarditis, antimyosin scintigraphy often demonstrates myocardial cell damage but histologic evaluation of the endomyocardial biopsy often fails to show evidence of myocarditis. Recently developed immunohistologic techniques appear to be more sensitive for the detection of myocardial inflammation than histologic analysis alone. Studies comparing antimyosin scintigraphy and immunohistologic analysis of the endomyocardial biopsy in patients with clinically suspected myocarditis are not yet available. METHODS: Sixty-five patients with clinically suspected myocarditis underwent antimyosin scintigraphy. Antimyosin antibody uptake was correlated with histologic and immunohistologic findings in the endomyocardial biopsy. RESULTS: Antimyosin scintigraphy showed evidence of myocardial cell damage in 36 (55%) of the 65 patients and was negative in 29 (45%) patients. Histologic analysis of the endomyocardial biopsy revealed myocarditis in nine patients: six had a positive and three had a negative antimyosin scan, respectively. Thirty (83%) of 36 patients with evidence of myocardial cell damage on antimyosin scintigraphy were histologically negative for myocarditis. Immunohistologic analysis showed evidence of myocarditis in 31 (86%) of 36 patients with a positive antimyosin scan and also in 17 (59%) of 29 patients with a normal scan (p < 0.047). CONCLUSIONS: Antimyosin scintigraphy often shows myocyte injury in patients with clinically suspected myocarditis. Histologic analysis of the endomyocardial biopsy alone is often negative, but additional immunohistologic analysis of the endomyocardial biopsy frequently provides evidence of myocardial inflammation in these patients. With immunohistologic analysis as the reference method, antimyosin scintigraphy has a high specificity but a lower sensitivity for the detection of myocarditis.