CIRCULATING CARDIAC-SPECIFIC AUTOANTIBODIES AS MARKERS OF AUTOIMMUNITY IN CLINICAL AND BIOPSY-PROVEN MYOCARDITIS

Aim Myocarditis and dilated cardiomyopathy may be phases of an organ-s pecific autoimmune disease of the myocardium. To provide evidence for autoimmune involvement in myocarditis, cardiac autoantibodies were det ected in patient sera from the Myocarditis Treatment Trial. Methods an d Results Cardiac antibody status was assessed by indirect immunofluor escence and by anti-alpha-myosin enzyme-linked immunosorbent assay in 53 patients from the Myocarditis Treatment Trial (35 males, aged 42 +/ - 15 years); all had clinical myocarditis, but only 24 were classified as having histological myocarditis (Dallas criteria). By immunofluore scence cardiac antibodies were more common in myocarditis (13/53) than in ischaemic (11/186, P=0.0001) or in normal controls (24/270, P=0.00 1). Abnormally raised anti-a-myosin antibodies were also more frequent in myocarditis (9/53) than in ischaemic (4/92, P=0.01) or normal cont rols (4/203 P=0.0001); 34% of myocarditis patients were positive with one or both tests. Similar proportions of patients with and without hi stological myocarditis had antibodies by immunofluorescence (8/24 vs 5 /29, P=ns) and by enzyme-linked immunosorbent assay (4/24 vs 5/29, P=n s). Conclusion The detection of disease-specific cardiac autoantibodie s supports autoimmune involvement in a subset of patients with clinica l myocarditis. The lack of correlation of antibody with biopsy feature s suggests that diagnosis of myocarditis should not be made on histolo gy alone. Autoimmune markers may provide adjunct diagnostic tools and identify patients in whom immunosuppression is of potential benefit.